Synchro Studio Examples

Synchro Studio 7 Examples

Examples Synchro Studio 7

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Table of Contents CHAPTER 1 - INTRODUCTION............................................................................................................................. 1 CHAPTER 2 - BASIC ISOLATED INTERSECTIONS ......................................................................................... 2

BASIC TWO-STAGE ISOLATED INTERSECTION ........................................................................................................... 2 Modeling with Synchro ......................................................................................................................................... 3

DUAL RING, EIGHT-PHASE CONTROLLER.................................................................................................................. 7 Modeling with Synchro ......................................................................................................................................... 8

SINGLE RING CONTROLLER WITH MORE THAN FOUR PHASES ................................................................................ 11 Modeling with Synchro ....................................................................................................................................... 11

CHAPTER 3 - CODING INTERCHANGES AND CLOSELY SPACED INTERSECTIONS......................... 14 SETTING UP A TIMING PLAN .................................................................................................................................... 14 SETTING UP LEADING ALTERNATING TIMING.......................................................................................................... 16 CODING OVERLAPS ................................................................................................................................................. 16 DIAMOND WITH LEADING ALTERNATING ................................................................................................................ 17 DIAMOND-LAGGING SIMULTANEOUS ...................................................................................................................... 24 DIAMOND INTERCHANGE WITH FRONTAGE ROADS ................................................................................................. 30 SINGLE POINT URBAN INTERCHANGE...................................................................................................................... 35 MULTIPLE INTERSECTIONS ON ONE CONTROLLER................................................................................................... 38 GROUP CONTROL EXAMPLE TWO............................................................................................................................ 43

CHAPTER 4 - SPECIAL CASES ........................................................................................................................... 46 SIX LEG INTERSECTION ........................................................................................................................................... 46

Modeling with Synchro ....................................................................................................................................... 46 CONTROLLER WITH MORE THAN NINE PHASES....................................................................................................... 49

Modeling with Synchro ....................................................................................................................................... 49 T-INTERSECTION WITH NON-CONFLICTING PEDESTRIAN MOVEMENT..................................................................... 52

Modeling with Synchro ....................................................................................................................................... 53 FLORIDA T-INTERSECTION ...................................................................................................................................... 55

Modeling with Synchro ....................................................................................................................................... 55 ARTERIAL WITH WIDE MEDIAN EXAMPLE .............................................................................................................. 58 FIXED CYCLE COORDINATED SYSTEM..................................................................................................................... 62 TWO WAY TRAFFIC CONTROL................................................................................................................................. 65

Modeling with Synchro ....................................................................................................................................... 65 ROUNDABOUTS (SIMULATED) ................................................................................................................................. 67

Modeling with Synchro ....................................................................................................................................... 67 CHANNELIZED RIGHT TURNS .................................................................................................................................. 69

Modeling with Synchro ....................................................................................................................................... 69


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Chapter 1 - Introduction The following sections include examples on coding Synchro and SimTraffic. They have been designed to start with basic coding of isolated intersections. A special section on coding interchanges is included for assistance with these complex types of coding problems. A section of special cases has also been included to provide guidance on some of Synchro and SimTraffic's more complex features.

Each of the examples includes a sample Synchro file that is included in your Trafficware installation directory when you install the software. New users are encouraged to attempt the basic coding problems from scratch. In the Basic Lessons, you will learn how to create the network, input lane geometry, traffic volumes and signal timing, and on some of the important measures of effectiveness that are included within Synchro.

In the latter examples, special illustrations of how to use the Ring-and-Barrier-Designer, the Cluster Editor, creating curved links, modeling a roundabout, coding a channelized right turn (pork chop) island and more will be discussed.


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Chapter 2 - Basic Isolated Intersections Basic Two-Stage Isolated Intersection The most basic type of intersection to analyze is the two-stage, pretimed isolated intersection. The figure below shows the lane configuration and phase assignments for a typical four-leg signalized intersection.

Phase 2 is the main street eastbound movement for the left, through and right.

Phase 4 is the side street southbound movement for the left through and right.

Phase 6 is the main street westbound movement for the left, through and right.

Phase 8 is the side street northbound movement for the left, through and right.

As the name of the example implies, there are two-stages of operation (east-west and north-south). However, there are 4 phases that are actually designated within the controller. This is an example of dual ring control where phase 2/6 (east-west) operate concurrently as well as do phase 4/8 (north-south).

The resulting dual ring structure is as follows:


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For dual ring controllers, only one phase per ring can be active and the active phase(s) must be on the same side of the barrier. For the example above, phase 2 and 4 are in ring A and phase 6 and 8 are in ring B. Phase 2 and 6 are in barrier 1 (left side) and phase 4 and 8 are in barrier 2 (right side). This dictates that phase 2 and 6 can operate simultaneously and phase 4 and 8 can operate simultaneously. For controller setting, these phases would normally have dual entry set.

For this example, single ring sequential phasing could also be used. In that case, phase 1 could operate the eastbound and westbound movements and phase 2 could operate the northbound and southbound movements as shown below.

Modeling with Synchro Filename: Basic 2-Stage.syn

Step 1. Create the Network To begin a new network, open Synchro and select the command File→New. From the MAP view (press [F2] if not already in the MAP view), create the network shown below (see the topic on Mapping out Links and Intersections in the Synchro Plus User Guide). Use a link length of 1000 feet.

To add a link to the map:

1A. Select the Add Link button or press the [A] key.

1B. Position the mouse cursor on the MAP view where you want the link to start, and click the left mouse button. The status indicators, at the lower-right corner of the view show the X and Y coordinates in feet (meters). Note: To cancel adding a link, press [Esc].

1C. Release the mouse button and move the cursor to the position on the window where you want the link to end. Click the left mouse button again. Refer to the status bar at the bottom of the window to see the length and direction of the link

To create the intersection, simply create another link that crosses the link created in steps A through C above. The intersection will be placed where the links cross.


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If you do not want an intersection to be placed where the links cross, hold the [Ctrl] key while drawing the link that crosses. This would be an overpass (or underpass). The elevation is set in the Node settings for each node on the end of the link.

Step 2. Enter Lane and Volume Data From the MAP view, click on the intersection created in step 1 and activate the LANE settings by pressing the Lane

View button or the [F3] key. Enter the lane data that is shown below:

See the appropriate LANE settings topics in the Synchro Plus User Guide. The values show in blue are calculated. Generally, these values are not overridden.

To add lanes, enter the number of lanes for that lane group. For each lane group, enter the number of lanes as a value from 0 to 8, or select the lane configuration from the drop down list.

For the through lane group, specify whether it shares with left or right traffic by pressing [R] or [L] or by selecting the appropriate configuration from the list.

Switch to the VOLUME settings by pressing the Volume View button or the [F4] key. Enter the volume data shown below:


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See the appropriate VOLUME settings topics in the Synchro Plus User Guide.

Step 3. Enter the Timing Data Since this is a basic intersection, you can use Phase Templates to quickly set up the timing for this intersection. In this example, the major street is east/west, therefore click on the [Options] button and then select Set to East-West Template Phases to set phases for an east-west arterial. This will automatically set the phase numbers as shown below:

To edit the phase templates to match local standards, use the command Options→Edit-Template-Phases.

For this example, the left and right turn phases are permitted. The controller type is pretimed. Use the default values for the remaining fields shown on the TIMING settings.

The basic information required to perform an analysis of a basic two-phase intersection is now entered. To set phase specific parameters, such as the minimum split, yellow and red times, and pedestrian interval settings, see the PHASING settings, in the Synchro Studio 7 User Guide. For this example, use the default values assigned in the PHASING options.

Step 4. Optimize Intersection Cycle Length Now that the basic data is entered, the next step is to find the best timing plan for this isolated pretimed intersection. Use the Optimize→Intersection-Cycle-Length command to set the intersection to the Natural Cycle Length. The Natural Cycle length is the lowest acceptable cycle length for an intersection operating independently. Synchro will automatically optimize the intersection splits when you perform this step. The resulting cycle length is shown in the Current Cycle Length field show on the left of the TIMING settings.

Step 5. Interpreting Results The final step is to interpret the measures of effectiveness (MOE) for the example. The most common MOEs are shown in the TIMING settings rows for each lane group.

The intersection wide MOE's for volume to capacity (v/c) ratio, delay and level of service (LOS) are shown in the left side of the TIMING settings.

The most commonly reported MOEs are the v/c ratio, the delay and the level of service.


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The v/c Ratio is the v/c ratio using actuated green times and cycle lengths. The v/c ratio indicates the amount of congestion for each lane group. Any v/c Ratio greater than or equal to 1 indicates that the approach is operating at above capacity.

The delay is a measure of the total delay, in seconds per vehicle, experienced for the given lane group. Version 6 introduced two new delay measurements. In addition to the traditional Control Delay, Synchro also includes a Queue Delay. The Total Delay is the combination of the two types of delay.

The LOS is a means of describing the operational efficiency of a given intersection based on the calculated delay. The range of service quality has been defined in terms of six LOS ranges (A to F). LOS A represents free flowing conditions with insignificant delays. LOS F represents forced flows (jammed conditions) with excessive delays. Under LOS F, queues may block upstream intersections.

To quickly print these results, use the command File→Print-Window.


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Dual Ring, Eight-Phase Controller A common, yet more complex example than the Basic Two-Stage Isolated Controller, is a dual ring, eight-phase controller. The following figure shows a sample lane configuration and phase assignments for a typical four-leg eight-phase signalized intersection.

Phase 1 is the main street protected westbound left (dual left turn lane).

Phase 2 is the main street eastbound movement for the through and right.

Phase 3 is the side street protected northbound left.

Phase 4 is the side street southbound movement for the through and right.

Phase 5 is the main street protected eastbound left (dual left turn lane).

Phase 6 is the main street westbound movement for the through and right.

Phase 7 is the side street protected southbound left.

Phase 8 is the side street northbound movement for the left, through and right.

The resulting dual ring structure is as follows:

For dual ring controllers, only one phase per ring can be active and the active phase(s) must be on the same side of the barrier. Notice that on the right side barrier, phase 4 leads phase 3. This is an example of a lagging left turn phase. The sequence in which phase will occur in ring A is 1-2-4-3.


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Modeling with Synchro Filename: Dual Ring.syn

Step 1. Create the Network To begin a new network, open Synchro and select the command File�New. From the MAP view (press [F2] if not already in the MAP view), create the network shown in below. The links are 1000' in length.

In the Link Settings, set a speed of 45 mph for both Main Street and 1st Street. Use the defaults for all other fields in the LINK SETTINGS window.

Step 2. Enter Lane and Volume Data From the MAP view, click on the intersection of Main Street & 1st Street and activate the LANE settings by

pressing the Lane View button or the [F3] key. Enter the lane data that is shown below:

INTID EBL EBT EBR WBL WBT WBR NBL NBT NBR SBL SBT SBR

Lanes and Sharing 3 2 2 1 2 2 1 1 1 0 1 1 0

Shared Lanes * 3 0 0 0 0 0 2 0 2

Lane Width (ft) 3 12 12 12 12 12 12 12 12 12 12 12 12

Storage Length (ft) 3 250 150 250 150 100 100

Storage Lanes (#) 3 2 1 2 1 1 1

Grade (%) 3 0 0 0 0

Leading Detector (ft) 3 50 300 50 50 350 50 50 300 50 300

Trailing Detector (ft) 3 0 144 0 0 144 0 0 0 0 0

* For Shared Lanes, 0 = None, 1 = Left, 2 = Right, 3 = Both (Shared with Through)

To add lanes, enter the number of lanes for that lane group. For each lane group, enter the number of lanes as a value between 0 and 5, or select the lane configuration from the drop down list.

For the through lane group, specify whether it shares with left or right traffic by pressing [R] or [L] selecting the appropriate configuration from the list.

Switch to the VOLUME settings by pressing the Volume View button or the [F4] key. Enter the volume data shown below:


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3 500 1500 100 100 500 100 100 200 50 100 200 50

Use the defaults for all other values in the VOLUME settings.

Step 3. Enter the Timing Data To start, you can use the Phase Templates to set up the initial timing for this intersection. In this example, the major street is east/west, therefore click on the [Options] button and select Set to East-West Template Phases to set phases for an east-west arterial. This will automatically set the phase numbers as shown below:

Notice the Turn Type for the left turns is set to Perm, by default. For this example, all the left turns are protected. Use the Turn Type setting drop down box and set all the left turn phases to Prot. If you prefer, you can set the phase numbers in the Protected and Permitted Phase rows. The Turn Type and phase number rows will now look like this:

Also, notice the dual ring structure shown above has the northbound left (phase 3) as a lagging left turn. To change this, set the phase 3 Lead/Lag row to lag. The Lead/Lag row is shown in the TIMING settings and the PHASING settings.

For this example, we will be analyzing the exiting conditions, therefore it is necessary to enter some additional information. For this example, we are using Actuated-Coordinated for the Controller Type field. For the Current Cycle Length, enter a value of 100 seconds.

The Offset Settings will have no effect on the results of this example and do not need to be modified since this is an isolated intersection. The reason for setting this up as an Actuated-Coordinated controller would be for future system analysis.

The final step to setting up the timing data is to enter the existing split information. To do this, you can enter the value in the Total Split row. The Total Splits for this example are shown below:


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To adjust a split with the mouse, move the mouse to the right side of a yellow + all red band on the current Splits and Phasing diagram shown at the bottom of the TIMING settings.

The information required to perform an analysis of a dual ring, eight-phase intersection is now complete. To set phase specific parameters, such as the minimum split, yellow and red times, and pedestrian interval settings, see the PHASING settings.

Step 4. Interpreting Results Now that the required data is entered, you can now interpret the existing condition measures of effectiveness (MOE) for the example.

The intersection wide MOE's are shown on the left side of the TIMING settings.

The most commonly reported MOEs are the volume to capacity ratio (Intersection v/c Ratio or Volume to Capacity Ratio) the delay (Total Delay, Control Delay and Queue Delay) and the Level of Service.

To quickly print these results, use the command File→Print-Window. For other more detailed reports, see the topic on Selecting Reports.

Step 5. Optimize Intersection Cycle Length Now that the basic data is entered and analyzed, the final step is to find the best timing plan for this isolated intersection. Use the Optimize→Intersection-Cycle-Length command to set the intersection to the Natural Cycle Length. The Natural Cycle length is the lowest acceptable cycle length for an intersection operating independently. Synchro will automatically optimize the intersection splits when you perform this step.

Prior to optimizing the file, perform a Save-As of the existing file and give this a new name. That way you can maintain the existing conditions file and the proposed optimized file for comparison purposes. The two files can be compared with the Multi-File Alternative Comparison Report.


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Single Ring Controller with More Than Four Phases Sometimes it is desirable to use a single ring and have the phases operate one at a time sequentially. The intersection shown in the previous example, Dual Ring, Eight-Phase Controller, can be coded as a single ring controller. This single ring configuration is how other software packages, such as TRANSYT, model signal timing.

To model the previous example as a single ring controller, the resulting ring structure is as follows (six stages):

Notice the phase number does not identify a single intersection movement, but a group of non-conflicting movements arranged in an established order of preferred sequence (stages). Each phase is individually timed and can be skipped if no demand is present for it. For the dual ring controller in the previous example, phase 1 identified the westbound left turn movement. For this single ring example, phase 1 identifies the movement of the westbound and eastbound left turns followed by phases 2 through 6, sequentially.

Modeling with Synchro Filename: Single Ring.syn

Step 1. Create the Network Creating the network is the same, whether using the dual-ring or single ring configuration. See Step 1 in the previous example, Dual Ring, Eight-Phase Controller for information on creating this example network.

Step 2. Enter Lane and Volume Data See Step 2 of the previous example, Dual Ring, Eight-Phase Controller for information on entering lane and volume data.

Step 3. Enter the Timing Data To enter single ring timing for a controller with more than 4 sequential phases, some set up is required. As you can see from the Single Ring Structure show above, there are 6 stages for this example. The first step to creating a six-stage, single ring (sequential) controller is to set up the appropriate ring structure in the Ring-and-Barrier-Designer.

Select the intersection and switch to the TIMING settings by pressing the TIMING settings button or the [F5] key. Then activate the Ring-and-Barrier-Designer by selecting Options> Ring-and-Barrier-Designer. Within the Ring-and-Barrier-Designer, select the option Non Standard Phasing from the Sequential Phasing box.

In the Ring-and-Barrier-Designer cells, enter the phases 1 through 6 sequentially in ring A as shown below:


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Select [OK].

Still within the TIMING settings [F5], proceed to set up the single ring timing. Keeping the single ring, six-stage structure defined above in mind, the next step is to enter the phase numbers for the individual movements. Starting in the Protected Phases row, enter the phase number(s) for the individual movements. For instance, the eastbound left occurs as a protected left phase during phase 1 and also continues as a protected left during phase 2. To code this, enter a 1 in the Protected Phases row for the EBL, then insert a space [space bar] and enter a 2. Notice the Turn Type for the EBL automatically become Prot. Continuing with the EBT, enter a 2 and a 3 separated with a space in the Protected Phases row. This codes the EBT movement to operate with phase 2 and 3. Continue entering the appropriate phases for the remaining movements. The resulting rows will appear as follows:

The Detector Phases will be the first phase entered in the Protected Phases row. If no protected phases are entered, it will be the first phase entered in the Permitted Phases row.

As in the previous example, set the Controller Type to Actuated-Coordinated and the Current Cycle Length to 100 seconds.

The final step to setting up the timing data is to enter the split information. To do this, you can enter the value in the Total Split row. The Total Splits for this example are shown in the Total Split row in the above graphic. The Total Split is the sum of all phases entered for the movement.


The information required to perform an analysis of a single ring, six-phase intersection is now complete. To set phase specific parameters, such as the minimum split, yellow and red times, and pedestrian interval settings, see the PHASING settings.


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Step 4. Interpreting Results Now that the required data is entered, you can now interpret the existing condition measures of effectiveness (MOE) for this example.


The most commonly reported MOEs are the volume to capacity ratio (Intersection v/c Ratio or v/c Ratio) the delay and the Level of Service.

Notice the results for this single ring example are different from the dual ring example, even thought the same basic data was used. This has to do with the inherent inflexibility of the single ring controller. Phases follow a fixed sequence and cannot change phase pair order. With the dual ring controller, a phase is allowed to change which concurrent phase it is operating with based on demand and the rules for dual ring control.

For instance, with the single ring controller shown above, the EBL movement is allowed to operate with 10 more seconds than the WBL. If the WBL for any given cycle has more demand than the EBL, it is not allowed to be given more green time than the EBL. With dual ring control, the WBL is allowed to have more green time if the demand is greater than that of the EBL.

To quickly print these results, use the command File→Print-Window. For other more detail reports, see the topic on Selecting Reports.

Step 5. Optimize Intersection Cycle Length Now that the basic data is entered and analyzed, the final optional step is to find the best timing plan for this isolated intersection. Use the Optimize→Intersection-Cycle-Length command to set the intersection to the Natural Cycle Length. The Natural Cycle length is the lowest acceptable cycle length for an intersection operating independently. Synchro will automatically optimize the intersection splits when you perform this step.


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Chapter 3 - Coding Interchanges and Closely Spaced Intersections Setting up a Timing Plan Setting up a timing plan for an interchange or closely spaced intersections can be a difficult and confusing task. There are many options to consider. Here is a step-by-step plan for setting up timing plans for these situations.

Step 1 Enter lane and volume data. See the LANE settings and the VOLUME settings.

Step 2 Select a controller scheme. Choose between Local and Group control, and between fixed and floating cycle length.

Step 3 Set up phasing for each intersection using Local Control. Even if Group control will be used, to start assume Local control.

Each intersection should use sequential phasing from a single ring. In most cases one intersection will use phases 1-2-3-4, and the other intersection will use phases 5-6-7-8. If there is a third or fourth intersection in the group, they can use additional phases 9-10-11-12 for example.

If necessary, use the Ring-and-Barrier-Designer to set up a phase sequences for each intersection.

If the intersections were previously set up under Group Control, use the Cluster Editor to return them to Local control. All intersections must be set up using Local Control to perform Cycle Length, Offset, and Phase Sequence Optimizations.

If this interchange has a movement with a high right turn volume, consider setting up a right turn phase as suggested in the topic Diamond with Heavy Right Turns.

Do not include extra phases such as phases 12 and 16 as shown in the Leading Alternating plan. These will be added later. If extra phases are part of the timing plan, remove them to aid in the optimization.

Make sure that phases are set up with Allow Lead/Lag Optimize set to 'Yes'. The Optimization will then be able to consider both leading and lagging alternatives.

Step 4 Optimize the network using the Optimize→Network-Cycle-Length command then use the Optimize→Network-Offsets command.

When choosing a cycle length pay careful attention to the queuing penalty MOE. This value is critical within an interchange

If using Local control, you are now finished.

If using Group Control, continue with steps 5 to 8.

Step 5 Determine the phase sequence to use.

Record the Phasing Order. Visit the TIMING settings for each intersection and write down the phase sequence.

Step 6 Determine the barrier change point(s). Visit the TIME-SPACE DIAGRAM window with [Max] option and observe the traffic band.


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The phase numbers listed here assume that you are using the same phase numbers as the examples.

If the internal left turn phases (1 and 5) are leading, and the through phases (2 and 6) do not coincide, the optimizer has automatically selected Leading Alternating Timing, see Setting up Leading Alternating Timing for special instructions.

Find a phase from each intersection that starts at about the same time. These phases will be listed first in the barrier sequence. Normally, the beginning of phases 4 and/or 8 make a good time to start the barrier. When looking at a time space diagram for the cross street, the red section indicates phases 4 and 8, the green sections indicates phases 2 and 6, and the hatched section represents phases 1 and 5.

If there are no pair of phases from each intersection that change within a few seconds of each other, it may be necessary to create a supplementary phase. This phase is placed at the beginning of the barrier to insure the internal offsets make good coordination. Normally this supplementary phase is equal to the travel time between intersections. The Leading Alternating timing plan uses two supplementary phases.

Step 7 Go to Cluster Editor. Attach the intersections to one controller.

Step 8 Go to the Ring-and-Barrier-Designer. Enter the phasing sequence determined in Step 6.

Step 9 Optimize the Splits and or Cycle Length.

If any movement is served by two or more phases, insure the Detector Phases are set correctly.

Go to the PHASING settings. Make sure phases are not being skipped or unless they are low volume. If a phase is being skipped, check the coding of the Detector Phases. It may be necessary in some cases to set the Recall to Minimum.

Step 10 Check queue lengths of internal movements for blocking problems. The queue lengths can be seen in the TIMING settings and in the Queue report. It is also helpful to observe queues using a microscopic simulation such as SimTraffic. It may not be possible to eliminate blocking queues 100%, but it should be possible to minimize their duration. If you encounter unacceptable internal queues, it may be necessary to consider an alternative timing plan.

Be sure to check the intersection coding, the recall or detector phases may need adjusting. SimTraffic can be used to observe operation and to insure that auxiliary phases are being serviced when appropriate.


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Setting up Leading Alternating Timing Setting up Leading Alternating Timing has a couple of tricks.

Perform steps 1 to 3 as described in Setting up a Timing Plan. In step 3 it is not necessary to set up for Local Control since we already know the phase sequence and barriers.

Steps 4 to 6 are not necessary since we have already decided the phase sequence to use.

Perform step 7 shown in Setting up a Timing Plan.

Go to the Ring-and-Barrier-Designer.

Use these phases:

Go to the TIMING settings for both intersections. For the off ramp movements 4 and 8, change the phases to 4+12 and 8+16 (the phases are separated by a space).

For the off ramp movements 4 and 8, insure the Detector Phases are 4+12 or 8+16. Be sure that 4 and 8 are listed first.

Set the Minimum Split and the Maximum Split for phases 12 and 16 as the travel time between the intersections.

Set Recall for phases 1, 5, 12 and 16 to Minimum.

Coding Overlaps This section discusses special considerations for any movement served by two or more phases, also called an overlap.

The listed phases will become the Detector Phases. The phase listed first will be used for split optimization.

For the heavy right turn example, the supplementary phase 7 should be listed before 8 so the split optimization for this movement is phase 7. This will keep the optimized split for phase 8 short.

Pay careful attention to Detector Phases. They are key to controlling split optimization, as well as skipping and gapping behavior with the actuated green times and in SimTraffic.

Normally the internal through movements will have overlaps of 1+2 and 5+6. Normally the first phase in the sequence should be the first Detector Phase listed. With a leading left 1, phase 1 is entered first (1, 2), with a lagging left 1, phase 2 is entered first (2, 1).

It may be necessary to code some phases with Minimum Recall to prevent skipping. An actual controller allows complex handling of detector calls that depend on the current phase settings. For example, the detectors for phase 8 can be programmed to call phase 2, only while phase 8 is green. If you observe phase skips in the PHASING settings or SimTraffic, it may be necessary to set the recall for some phases to Minimum. Pay close attention to phases 1, 2, 5, 6, and any auxiliary phases.


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Diamond with Leading Alternating This diamond interchange example is an example of how to code a diamond interchange with leading alternating timing. For details on coding diamond interchanges, see the topic on Setting up a Timing Plan and on Setting up Leading Alternating Timing in this chapter. The examples presented here will closely follow the steps identified in these topics. Notice that if you follow the steps correctly, you do not know with certainty the actual ‘best’ operation for the interchange from the onset.

Filename: Diamond – Leading Alt.syn

Step 1A. Create the Network To begin a new network, open Synchro and select the command File→New. From the MAP view (press [F2] if not already in the MAP view), create the network shown below (see the topic on Mapping out Links and Intersections). The distance between intersections for this example is 414 feet. Be sure to use the node numbers that are shown in the graphic below.

To draw short links, use the Options→MAP-Settings command to reduce the size of the width of the links and the radius of the nodes. Also, zoom in on the area where the network will be created to give more precision when creating links.

In the LINK SETTINGS window, set a speed of 40 mph for the Main Street and 30 mph for the ramps. Use the defaults for all other fields in the LINK SETTINGS window.

Step 1B. Enter Lane and Volume Data From the MAP view, click on the intersection of Main Street & SB Ramp and activate the LANE settings by

pressing the Lane View button or the [F3] key. Enter the lane data that is shown below:



Shared Lanes * 1 0 0 0 0 0 0 0 1

Lane Width (ft) 1 12 12 12 12 12 12 12 12 12 12 12 12

Storage Length (ft) 1 150 150 150

Storage Lanes (#) 1 1 1 1

Grade (%) 1 0 0 0 0

Leading Detector (ft) 1 250 10 50 250 50 50 50


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Trailing Detector (ft) 1 244 0 0 244 0 0 0


Shared Lanes * 2 0 0 0 0 0 1 0 0

Lane Width (ft) 2 12 12 12 12 12 12 12 12 12 12 12 12

Storage Length (ft) 2 150 150 150

Storage Lanes (#) 2 1 1 1

Grade (%) 2 0 0 0 0

Leading Detector (ft) 2 50 250 250 10 50 50 50

Trailing Detector (ft) 2 0 244 244 0 0 0 0

* For Shared Lanes, 0 = None, 1 = Left, 2 = Right, 3 = Both (Shared with Through)

Next, switch to the VOLUME settings by pressing the Volume View button or by pressing [F4]. At each ramp, enter the volumes as shown in the map figure at the start of this example or see the table below. Use the default values for Conflicting Peds, Peak Hour Factor, Growth Factor, Heavy Vehicles, Bus Blockages and Adj Parking Lane.


1 400 43 100 200 800 20 100

2 300 900 200 120 100 10 200

Since this is an example of two closely spaced intersections, it is important to specify the origin and destination of the ramp left turns. This is done to prevent vehicles from unrealistically turning left twice (left from the ramp and then immediately left again back onto the next ramp).

To do this, use the LINK ORIGIN-DESTINATION VOLUME settings. This window displays Movement Weighting Factors that control how volume is allocated between input and output volumes.

The LINK ORIGIN-DESTINATION VOLUME settings is available from the VOLUME settings and the LINK

SETTINGS window. For this example, switch to the MAP view by pressing the MAP view button or by pressing [F2]. To activate the LINK ORIGIN-DESTINATION VOLUME settings, double click on the Main Street

link between the NB and SB ramps, then select the Link O-D Volumes button for the westbound direction. The Link O-D Volumes button for the westbound direction appears with a blue caption when all Movement Weighting Factors are 1. The LINK ORIGIN-DESTINATION VOLUME settings will appear as shown below.


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Notice that of the 109 vehicles turning left from the NB Ramp, 36 of these will immediately make another left turn onto the SB Ramp by default calculation. To modify this, enter a reasonable weight factor in the From NBL Weight row for the WBL column (the cell under the 36). For this example, enter a weight value of 0.10. This will change the value of 36 vehicles making the immediate left turn to a value of 9 vehicles. No other values within this window need to be modified. Synchro will automatically update the other fields in this window.

Select [Close].

Do the same for the EB direction by entering a 0.05 in the From SBL Weight row for the EBL column (the cell under the 217). This will change the value of 217 to 63.

If one or more Movement Weighting factors have been changed, the Link O-D Volumes button appears with a red caption.

Step 2. Select a Controller Scheme At this point, the basic information is entered into Synchro for analysis and optimization. The next step is to choose between Local and Group control and between fixed and floating cycle length. For more details, see the Signal Timing Background chapter on the topics Group Control versus Local Control and on Fixed Cycle Length versus Floating Cycle Length.

In many cases the decision whether to use Local or Group control will depend on the existing equipment. Unless you are working on new construction or a major update, the timing plans must be generated to match the existing equipment.

If coordination with adjacent signals is needed, a fixed cycle length is required.

For this example, we will assume that this is new construction and we can determine the control type after further analysis.

Step 3. Set up Local Phasing To start, each intersection should be set up to use Local Control. This is important so Synchro can perform the appropriate Cycle Length, Offset, and Phase Sequence Optimizations. Each intersection should use sequential phasing from a single ring. For this example, Main Street & SB ramp will use phases 1-2-4 and Main Street & NB ramp will use phases 5-6-8. To do this, no changes are need to the default ring structure shown in the Ring-and-Barrier-Designer.

The Local timing information for the SB ramp is as follows:


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Notice that the WBT phase is also active during the WBL phase (phase 1). Therefore, enter a 2 and a 1 separated by a space in the Protected Phases row for the WBT movement. Notice that the 2 was entered first so Synchro uses this in the split optimization. The appropriate Detector Phases are updated automatically according to the input for the Phases rows.

The Local timing plan for the NB ramp is as follows:

Even though we know from the name of this example the ultimate timing plan that will be selected, it is important to NOT include the extra phase 12 and 16 as shown in the Leading Alternating plan. These will be added later as necessary based on the optimization step.

Step 4. Optimize the Network The next step is to optimize the system as a network of two local intersections. Optimize the network using the Optimize→Network-Cycle-Length command then use the Optimize→Network-Offsets command. For this example, use a cycle length range from 50 seconds to 150 seconds at 10-second increments.

For this example, Synchro recommends a 60-second cycle length for the network. If this were an example for Local control, the example would be finished.

Step 5. Determine the Phase Sequence The next step is to determine the phase sequence determined by Synchro (if Allow Lead/Lag Optimize? was set to "Yes" prior to optimization as recommended). The resulting phase sequence and optimized splits for Main St & SB Ramp (node #1) are as follows:

Notice, Synchro has recommended that phase 1 leads phase 2.

The resulting phase sequence for Main St & NB Ramp is as follows:


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Step 6. Determine the Barrier Change Point The next step is to determine the barrier change points. Go to the Time-Space diagram and observe the traffic bands as shown in the following graphic:

Notice that phase 1 and 5 are leading, and phase 2 and 6 DO NOT coincide. This would suggest a Leading Alternating Timing plan. Before setting up the leading alternating timing plan, first perform step 7, attaching the intersections

Step 7. Attach the Intersections to One Controller To start, set up the file for two intersections working with one controller. Use the Cluster Editor to select the two intersections working with one controller. Select the intersection of Main Street & SB Ramp (node #1) and switch to the PHASING settings (the Cluster Editor can also be accessed through the TIMING settings).

Activate the CLUSTER EDITOR window by selecting the [Options] button and then select Cluster Editor.

Click on the intersection of Main Street & NB Ramp to add this intersection to the cluster. The resulting CLUSTER EDITOR window will appear as shown below.


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Notice that the color for node #2 (Main Street and NB Ramp) has changed. This color will be used in the TIMING and PHASING settingss to clearly define which intersection data is being modified.

Select [OK].

Step 8. Setting up the Ring Structure The next step to creating a Leading Alternating Timing plan is to set up the appropriate ring structure in the Ring-and-Barrier-Designer. The key is to allow one movement to operate on both sides of the dual ring barrier. The ring structure for a dual ring, Leading Alternating diamond controller is as follows:

Notice that the south bound and northbound ramp movements are allowed to cross the barrier by reassigning their phase number (4+12, 8+16). For instance, The west ramp southbound movements are allowed to operate within the right barrier as phase 4. It is then allowed to cross into the left side barrier and continue to operate as phase 12.

To set up this structure, switch to the PHASING settings or TIMING settings and activate the Ring-and-Barrier-Designer by selecting the [Options] button and then Ring-and-Barrier-Designer. Within the Ring-and-Barrier-Designer, select the button [Diamond 4].

The Ring-and-Barrier-Designer will automatically appear as shown below:

Select [OK].


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Switch back to the TIMING settings [F5], and proceed to set up the dual ring timing.

For the off ramp movements, change the southbound phase 4 to phase 4+12 and phase 8 to 8+16 (separate the phase numbers with a space. The resulting rows are shown below.

Main St & SB Ramp:

Main St & NB Ramp:

In the PHASING settings, insure that no Pedestrian Phase is set for phase 12 and 16 and set the Minimum Split and the Maximum Split as the travel time between the intersections. For this example, it is approximately 8 seconds. Set the Recall for phases 1, 5, 12 and 16 to Minimum.

Step 9. Optimize Intersection Cycle Length Now that the basic data is entered and analyzed, the next step is to find the best timing plan for this interchange. Use the Optimize→Intersection-Cycle-Length command to set the intersection to the Natural Cycle Length. The Natural Cycle length is the lowest acceptable cycle length for an intersection operating independently. Synchro will automatically optimize the intersection splits when you perform this step.


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Diamond-Lagging Simultaneous The following example will show how to code a diamond interchange with lagging simultaneous operation. For details on coding diamond interchanges, see the topic on Setting up a Timing Plan in this chapter. The examples presented here will closely follow the steps identified in these topics. Notice that if you follow the steps correctly, you do not know with certainty the actual ‘best’ operation for the interchange from the onset. That is, whether to use leading alternating, lagging simultaneous or something else.

Filename: Diamond Lag Lag.syn

Step 1A. Create the Network To begin a new network, open Synchro and select the command File→New. From the MAP view (press [F2] if not already in the MAP view), create the network shown below (see the topic on Mapping out Links and Intersections). The distance between intersections for this example is 300 feet. The distance for links 2-8 and 1-5 is also 300 feet. Node 5 and 8 are bend nodes used to create a lane taper (2 lanes to 1 lane). Be sure to use the node numbers that are shown in the graphic below.

To draw short links, use the Options→MAP-Settings command to reduce the size of the links and the radius of the nodes. Also, zoom in on the area where the network will be created to give more precision when creating links.

In the LINK SETTINGS window, set a speed of 40 mph for the Main Street and 45 mph for the ramps. Use the defaults for all other fields in the LINK SETTINGS window.

Notice that the ramps have a bend node (nodes 5 and 8) on the downstream portion of the ramps. This is a taper point where the ramp changes from 2 lanes to 1. To create this taper, perform the steps identified in the figure shown above. This is performed after entering the basic lane information.


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Step 1B. Enter Lane and Volume Data From the MAP view, click on the intersection of Main Street & SB Ramp and activate the LANE settings by

pressing the Lane View button or the [F3] key. The basic lane information was previously entered in step 1A. Continue by entering the LANE settings data that is shown below:

Repeat the same steps for the intersection of Main Street & NB Ramp, entering the following lane data:

This is a special example of how turning lanes can continue through a downstream node. Consider the figure below for this example:


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The EB left at node 2 (NB Ramp) has 2 lanes with one 100’ storage lane (lane 5 shown in the figure). The outside left lane (lane 4) begins 250’ west of node 1 (SB Ramp). To code this at node 2 for the EBL column, enter 2 for Lanes and Sharing, 100 for Storage Length and 1 for Storage Lanes. Then, switch to node 1 for the EBL column and enter 250 for Storage Length and 1 for Storage Lanes. Do the same for the WB direction.

Next, switch to the VOLUME settings by pressing the Volume View button or by pressing [F4]. At each ramp, enter the volumes as shown in map figure at the start of this example. Use the default values for Conflicting Peds, Peak Hour Factor, Growth Factor, Heavy Vehicles, Bus Blockages and Adj Parking Lane.

Since this is an example of two closely spaced intersections, it is important to specify the origin and destination of the ramp left turns. This is done to prevent vehicles from unrealistically turning left twice (left from the ramp and then immediately left again back onto the next ramp).

To do this, use the LINK ORIGIN-DESTINATION VOLUME settings. This window displays Movement Weighting Factors that control how volume is allocated between input and output volumes.

For this example, use a weight factor of 0.10 in the From NBL Weight row for the WBL column and a 0.05 weight factor in the From SBL Weight row for the EBL column.

Select [Close].




For this example, we will assume that this is new a new installation and we can determine the control type after further analysis.

Step 3. Set up Local Phasing To start, each intersection should be set up to use Local Control. This is important so Synchro can perform the appropriate Cycle Length, Offset, and Phase Sequence Optimizations. Each intersection should use sequential


27

phasing from a single ring. For this example, Main Street & SB ramp will use phases 1-2-4 and Main Street & NB ramp will use phases 5-6-8. To do this, switch to the Ring-and-Barrier-Designer for each intersection. For the SB Ramp, enter 4-2-1 in ring A of barrier 1. For the NB Ramp, enter 8-6-5 in ring B of barrier 1.

For this example, use an actuated coordinated controller and use the east/west direction as the offset reference phase.

The Local timing information for the SB ramp is as follows:

Notice that the WBT phase is also active during the WBL phase (phase 1). Therefore, enter a 2 and a 1 separated by a space in the Protected Phases row for the WBT movement. Notice that the 2 is entered first so Synchro uses this in the split optimization. The appropriate Detector Phases are updated automatically according to the input for the Phases rows.

The Local timing plan for the NB ramp is as follows:


For this example, Synchro recommended a 70-second cycle length for the network. If this were an example for Local control, the example would be finished.

Step 5. Determine the Phase Sequence The next step is to determine the phase sequence determined by Synchro (if Allow Lead/Lag Optimize? was set to "Yes" prior to optimization as recommended). The resulting phase sequence and optimized splits for Main St & SB Ramp (node #1) are as follows:

Notice, Synchro has recommended that phase 2 leads phase 1.

The resulting phase sequence for Main St & NB Ramp is as follows:


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Notice that phase 1 and 5 are lagging, and phase 2 and 6 DO coincide (within 2 seconds). This would suggest a Lagging Simultaneous Timing plan.

Step 7. Attach the Intersections to One Controller To start, set up the file for two intersections working with one controller. Use the Cluster Editor to select the two intersections working with one controller. Select the intersection of Main Street & SB Ramp (node #1) and switch to the PHASING settings (or the TIMING settings).

Activate the CLUSTER EDITOR window by clicking on the [Options] button and then select Cluster Editor.

Click on the intersection of Main Street & NB Ramp to add this intersection to the cluster.

Notice that the color for node #2 (Main Street and NB Ramp) has changed. This color will be used in the TIMING and PHASING settingss to clearly define which intersection data is being modified.

Select [OK].

Step 8. Setting up the Ring Structure The next step is to set up the appropriate ring structure in the Ring-and-Barrier-Designer.

Since each intersection was set up in a single ring in step 3, no additional modifications are required.


29



30

Diamond Interchange with Frontage Roads The following example will show how to code a diamond interchange with frontage roads as shown below.

For details on coding diamond interchanges, see the topic on Setting up a Timing Plan in this chapter. The examples presented here will closely follow the steps identified in these topics. Notice that if you follow the steps correctly, you do not know with certainty the actual ‘best’ operation for the interchange from the onset.

Filename: Diamond w Front Roads.syn

Step 1A. Create the Network To begin a new network, open Synchro and select the command File→New. From the MAP view (press [F2] if not already in the MAP view), create the network shown below (see the topic on Mapping out Links and Intersections). Be sure to use the node numbers that are shown in the graphic below.



31

In the LINK SETTINGS window, set the speeds as shown in the figure above. Use the defaults for all other link settings.

Step 1B. Enter Lane and Volume Data From the MAP view, click on the intersection of Main Street & SB Frontage Road and activate the LANE settings

by pressing the Lane View button or the [F3] key. The basic lane information was previously entered in step 1A. Continue by entering the LANE settings data that is shown below:

Node EBL EBT EBR WBL WBT WBR NBL NBT NBR SBL SBT SBR

Lanes and Sharing 1 2 1 2 1 2

Storage Length (ft) 1 100

Storage Lanes (#) 1 1

Leading Detector (ft) 1 250 50 250 50 50

Trailing Detector (ft) 1 244 0 244 0 0






The Frontage Road and Ramp merge points (nodes 9, 11, 13 and 15) are unsignalized intersections without any turn bays or detectors.

Next, switch to the VOLUME settings by pressing the Volume View button or by pressing [F4]. At each intersection, enter the volumes as shown in map figure at the start of this example. Use the default values for Conflicting Peds, Peak Hour Factor, Growth Factor, Heavy Vehicles, Bus Blockages and Adj Parking Lane.


32

For this example, we will use the default values determined within the LINK ORIGIN-DESTINATION VOLUME settings. This is appropriate since U-turn movements will be more apparent in this example. An example would be a vehicle traveling on the SB off ramp, turning left (EB) onto Main Street and turning left again to proceed north on the NB Frontage Road.




For this example, we will assume that group control is to be used.

Step 3. Set up Local Phasing To start, each signalized intersection should be set up to use Local Control. This is important so Synchro can perform the appropriate Cycle Length, Offset, and Phase Sequence Optimizations. Each intersection should use sequential phasing from a single ring. For this example, Main Street & SB Frontage Road will use phases 4-2-1 and Main Street & NB Frontage Road will use phases 8-6-5. To do this, switch to the Ring-and-Barrier-Designer for each intersection. For the SB Ramp, enter 4-2-1 in ring A of barrier 1. For the NB Ramp, enter 8-6-5 in ring B of barrier 1.


The Local timing information for the SB Frontage Road is as follows:

Notice that the WBT phase is also active during the WBL phase (phase 1). Therefore, enter a 2 and a 1 separated by a space in the Protected Phases row for the WBT movement. Phase 2 is entered first so Synchro uses this in the split optimization. The appropriate Detector Phases are updated automatically according to the input for the Phases rows.

The Local timing plan for the NB Frontage Road is as follows:


33


For this example, Synchro recommended a 60-second cycle length for the network. If this were an example for Local control, the example would be finished.

Step 5. Determine the Phase Sequence The next step is to determine the phase sequence determined by Synchro (if Allow Lead/Lag Optimize? was set to "Yes" prior to optimization as recommended). The resulting phase sequence and optimized splits for Main St & SB Frontage Road (node #1) are as follows:

Notice, Synchro has recommended that phase 2 leads phase 1 (lagging left).

The resulting phase sequence for Main St & AB Frontage Road (node #2) is as follows:

Now, Synchro has recommended that phase 5 leads phase 6 (leading left)



34

Phase 1 is lagging, phase 5 is leading, and phase 2 and 6 DO coincide (within 2 second). This would suggest a Lag-Lead Timing plan.

Step 7. Attach the Intersections to One Controller To start, set up the file for two intersections working with one controller. Use the Cluster Editor to select the two intersections working with one controller. Select the intersection of Main Street & SB Frontage Road (node #1) and switch to the PHASING settings (the Cluster Editor can also be accessed through the TIMING settings).

Activate the CLUSTER EDITOR window by selecting the [Options] button and then select Cluster Editor.

Click on the intersection of Main Street & NB Frontage Road to add this intersection to the cluster.

The color for node #2 (Main Street and NB Frontage Road) has changed. This color will be used in the TIMING and PHASING settingss to clearly define which intersection data is being modified.

Select [OK].

Step 8. Setting up the Ring Structure The next step is to set up the appropriate ring structure in the Ring-and-Barrier-Designer. By combining the two local timing plans, the phases 2 and 6 do not coincide. To do this, switch to the Ring-and-Barrier-Designer and configure as shown below so that phase 2 and phase 6 are at the beginning of the barrier change point.

Phase 1 is still lagging phase 2 and phase 5 is still leading phase 6 (even though phase 5 appears at the end of the ring).



35

Single Point Urban Interchange The single point urban interchange (SPUI) is similar to a diamond interchange. The primary difference between the two interchanges is that all four left turn movements are controlled by a single traffic signal in the SPUI. The SPUI also requires less right-of-way than a diamond interchange. The following example will show how to code a SPUI.

Filename: Single Point.syn


To draw short links, use the Options→MAP-Settings command to reduce the width of the links and the radius of the nodes. Also, zoom in on the area where the network will be created to give more precision when creating links.


36

In the LINK SETTINGS window, set the speeds as shown in the figure above. Set the turning speed for all left turns at node 1 to 25 mph (see the topic on Turning Speed in the LANE settings). Also, one freeway merge is modeled in this example at node 6.

Be sure to follow the instruction on how to code a freeway merge in the topic on Freeway Links.

Step 1B. Enter Lane and Volume Data

From the MAP view, click on node 1 and activate the LANE settings by pressing the Lane View button or the [F3] key and enter the lane data as shown in the image above.

The EB left turn bay at node 1 extends 250' beyond node 2 and the WB left turn bay extends 250 beyond node 3. All other intersections (nodes 4, 5, 6, 11, and 12) are unsignalized intersections. Node 5 and Node 11 have 200' left turn bays. The example Diamond-Lagging Simultaneous illustrates how to code a turn bay that extends through an upstream node.

Next, switch to the VOLUME settings by pressing the Volume View button or by pressing [F4]. At each intersection, enter the volumes as shown in the table below. Use the default values for Conflicting Peds, Peak Hour Factor, Growth Factor, Heavy Vehicles, Bus Blockages and Adj Parking Lane.

Hourly Volume

Node EBL EBT EBR WBL WBT WBR NBL NBT NBR SBL SBT SBR NEL NWL NWR SEL SWL

1 800 1000 800 700 600 700

2 1800 500 1300 1000

3 1700 1500 1200 600

4 1200 800

5 700 1000

6 3000 2000

11 600 600

12 500 800

A SPUI will have much higher lost times compared to a typical intersection due to the large paths through the intersection. An urban interchange typically has left turn paths through the intersection of 160 feet or more. In this example, the lost time for the left should be set to 8 seconds and 6 seconds for the through movements at node 1. For node 2 and 3, a lost time of 4 seconds can be used for all movements since these intersection operate like a typical intersection.





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For this example, node 1, 2 and 3 are signalized. It is assumed that group control (one controller) is used for these intersections.

Step 3. Set up Group Control As defined in Step 2, the three intersections will operate under group control. The NBR at node 3 will always operate with the WBL at node 1 and the SBR at node 2 will always operate with the EBL at node 1.

To attach the three intersections, use the Cluster Editor.

Step 4. Entering the Timing Data Switch to the TIMING settings [F5] for node 1 to proceed with coding the example. For this example, set the Controller Type to Actuated-Uncoordinated.

The next step is to enter the phase numbers for the individual movements. Starting in the Protected Phases row, enter the phase number(s) for the individual movements. All of the left turn movements are Protected phases. The listed phases will become the Detector Phases. The phase listed first will be used for split optimization.

For node 1, the phase numbers for the appropriate movements are as follows:

EBL: Phase 5

EBT: Phase 2

WBL: Phase 1

WBT: Phase 6

SEL: Phase 7

NWL: Phase 3

For node 2, the phase numbers for the movements are as follows:

EBT/EBR: Free

WBT: Phase 6 and Phase 8 (enter a '6' and an '8' separated by a space)

SBR: Phase 5

For node 3, the phase numbers for the movements are as follows:

EBT: Phase 2 and Phase 4

WBT/WBR: Free

NBR: Phase 1

One of the key issues with a SPUI is the long yellow and all red times used due to the large intersection created. For this example, use a Yellow of 5.0 seconds and an All Red time of 3.0 seconds in the PHASING settings.

Step 5. Optimize the Network The final step is to optimize the intersection cycle length. To do this, use the command Optimize→Intersection-Cycle-Length. The Splits will be automatically optimized with this step.

For this example, Synchro has recommended a 90-second cycle length for the group of intersections. The resulting Splits and Phasing Diagram will appear as shown below:


38

Multiple Intersections on One Controller A common use of Group Control (multiple intersections on one controller) is for that of a dogleg intersection. The figure below shows the lane configuration of a typical dogleg intersection in which one controller will operate both intersections.

There are many potential timing plans that could be used for such an intersection; the limitation may be due to controller features or other physical limitations. In general, setting up a timing plan for a dogleg intersection is similar to setting up a timing plan for a diamond interchange. See the topic on Setting up a Timing Plan in the Diamond Interchange examples for the steps that should be used to set up a timing plan with Synchro.

Filename: 2 Inter One Controller.syn

Step 1A. Create the Network To begin a new network, open Synchro and select the command File→New. From the MAP view (press [F2] if not already in the MAP view), create the network shown below (see the topic on Mapping out Links and Intersections).


39

The distance between 1st Street and 2nd Street is 320 feet.

Use the node numbers shown above.

Use the defaults for all the fields in the LINK SETTINGS window.

Step 1B. Enter Lane and Volume Data From the MAP view, click on the intersection of Main Street & 1st Street and activate the TIMING settings by

pressing the TIMING settings button or the [F5] key. Enter the lane and volume data that is shown below (or see the Lane and Volume diagrams shown in Step 1A):

Repeat the same steps for the intersection of Main Street & 2nd Street, entering the following lane and volume data:

To add more detailed information, such as turn bay lengths and peak hour factors, switch to the LANE settings and/or the VOLUME settings.




For this example, it is assumed that both intersections are working with one controller. The initial steps to determining the best timing plan assume local phasing as shown in Step 3.

Step 3. Set up Local Phasing To start, each intersection should be set up to use Local Control. This is important so Synchro can perform the appropriate Cycle Length, Offset, and Phase Sequence Optimizations. Each intersection should use sequential phasing from a single ring. For this example, Main Street & 1st Street will use phases 1-2-4 and Main Street & NB ramp will use phases 5-6-8. To do this, switch to the Ring-and-Barrier-Designer for each intersection. For the 1st Street, enter 1-2-4 in ring A of barrier 1. For the 2nd Street, enter 5-6-8 in ring B of barrier 1.


The Local timing information for 1st Street is as follows:


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Notice that the WBT phase is also active during the WBL phase (phase 1). Therefore, enter a 2 and a 1 separated by a space in the Protected Phases row for the WBT movement. Phase 2 is entered first so Synchro uses this in the split optimization. The appropriate Detector Phases are updated automatically according to the input for the Phases rows. The WBL movement is protected and permitted, therefore, the Permitted Phases row for the WBL should be a 1 and a 2 (separated with a space). The NBR overlaps with the WBL, therefore a 1 should be entered in the Protected Phases row for the NBR.

The Local timing plan for the 2nd Street is as follows:


For this example, Synchro recommended an 90-second cycle length for the network. If this were an example for Local control, the example would be finished.

Step 5. Determine the Phase Sequence The next step is to determine the phase sequence determined by Synchro (if Allow Lead/Lag Optimize? was set to "Yes" prior to optimization as recommended). The resulting phase sequence and optimized splits for Main St & 1st Street (node #1) are as follows:

Notice that Synchro has recommended that phase 1 leads phase 2.

The resulting phase sequence for Main St & 2nd Street is as follows:


41


Notice that phase 1 is leading, phase 5 is lagging, and phase 2 and 6 DO coincide (within 6 seconds). This would suggest a Lead-Lag Timing plan.

Step 7. Attach the Intersections to One Controller To start, set up the file for two intersections working with one controller. Switch to the Cluster Editor to select the two intersections working with one controller.

Click on the intersection of Main Street & 2nd Street to add this intersection to the cluster.

Notice that the color for node #2 (Main Street and 2nd Street) has changed. This color will be used in the TIMING and PHASING settingss to clearly define which intersection data is being modified.

Select [OK].

Step 8. Setting up the Ring Structure The next step is to set up the appropriate ring structure in the Ring-and-Barrier-Designer. By combining the two local timing plans, the phases 2 and 6 do not coincide. To do this, switch to the Ring-and-Barrier-Designer and configure as shown below so that phase 2 and phase 6 are at the beginning of the barrier change point.


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Phase 1 is still leading phase 2 and phase 5 is still lagging phase 6 (even though phase 1 appears at the end of the ring)

Step 9. Optimize Intersection Cycle Length Now that the basic data is entered and analyzed, the next step is to find the best timing plan for this intersection. Use the Optimize→Intersection-Cycle-Length command to set the intersection to the Natural Cycle Length. The Natural Cycle length is the lowest acceptable cycle length for an intersection operating independently. Synchro will automatically optimize the intersection splits when you perform this step.


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Group Control Example Two This example is another example of modeling two intersections with one controller, or Group Control.

Filename: Group Control 2.syn



Use the defaults for the values in the LINK SETTINGS window.

Step 1B. Enter Lane and Volume Data

From the MAP view, click on node 1 or 2 and activate the LANE settings by pressing the Lane View button or the [F3] key. Enter the LANE settings data that is shown below for each of the intersections:


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Node NBL NBT NBR SBL SBT SBR EBL EBT EBR WBL WBT WBR


Storage Length (ft) 1 250 250 100 100 200 250 200

Storage Lanes (#) 1 1 1 1 1 1 1 1

Leading Detector (ft) 1 50 50 50 50 50 50 50 50 50 50 50 50

Trailing Detector (ft) 1 0 0 0 0 0 0 0 0 0 0 0 0


Storage Length (ft) 2 100 100 200 250 200 250 200

Storage Lanes (#) 2 1 1 1 1 1 2 1

Leading Detector (ft) 2 50 50 50 50 50 50 50 50 50 50 50

Trailing Detector (ft) 2 0 0 0 0 0 0 0 0 0 0 0

Next, switch to the VOLUME settings by pressing the Volume View button or by pressing [F4]. At each intersection, enter the volumes as shown in map figure at the start of this example. Use the default values for Conflicting Peds, Peak Hour Factor, Growth Factor, Heavy Vehicles, Bus Blockages and Adj Parking Lane.




For this example, node 1 and 2 are signalized and that group control (one controller) is used for these intersections.

Step 3. Set up Group Control As defined in Step 2, the two intersections will operate under group control. To attach the three intersections, use the Cluster Editor. Select node #1 and switch to the PHASING settings (or the TIMING settings).


Click on node #1 and then on node #2 to add these intersections to the cluster.

Notice that the color for node #1 has changed. This color will be used in the TIMING and PHASING settingss to clearly define which intersection data is being modified.

Select [OK].

Step 4. Entering the Timing Data The phase numbers used for this example are shown below:


45

Shown at the bottom of the figure is the dual ring phase structure. This first step is to switch to the Ring-and-Barrier-Designer and enter the phases as shown below in the above graphic.

Switch to the TIMING settings [F5] for node 1 to proceed with coding the example. For this example, set the Controller Type to Actuated-Coordinated.

Enter the appropriate phase numbers in the Protected Phases and Permitted Phases rows. All left turn movements are either Split or Protected.

Step 5. Optimize the Network The final step is to optimize the intersection cycle length. To do this, use the command Optimize→Intersection-Cycle-Length. The Splits will be automatically optimized with this step.

For this example, Synchro has recommended a 100-second cycle length for the group of intersections. The resulting Splits and Phasing Diagram will appear as shown below:


46

Chapter 4 - Special Cases Six Leg Intersection Synchro allows you to model intersections with five or more legs directly. Columns are included so up to six movements per approach can be coded (L, L2, T, R, R2, U). Take the following six-leg intersection for example.

When drawing links, the movement headings are automatically labeled. All available turn movements can be modeled for the above example. Columns are added in the data entry screens to model "hard" and "soft" left and right turn movements when you add links. In addition, you can model U-turn movements (to activate U-turns, use the keystrokes [Ctrl]+U.) In previous versions of Synchro, each approach was limited to 3 turning movements and in some cases to 2 turning movements.

Modeling with Synchro Filename: 6 Leg Intersection.syn

Step 1. Create the Network To begin a new network, open Synchro and select the command File→New. From the MAP view (press [F2] if not already in the MAP view), create the network shown below (see the topic on Mapping out Links and Intersections).


47

You can name the streets as show above. E/W Street is 45 MPH and N/S and Diag. Street are both 40 MPH. Use the defaults for all other fields in the LINK SETTINGS window.

Step 2. Enter Lane and Volume Data From the MAP view, click on the intersection E/W St. & Diag. St. and activate the LANE settings by pressing the Lane View button or the [F3] key. Enter the lane data that is shown above.

In the LANE settings, the movement abbreviation followed by a "2" indicates the "hard" movement. For instance, the EBL2 defines the hardest eastbound left turn movement (E/W St. left onto N/S St.).

To code the exclusive E/W St. left to N/S St., select the appropriate picture from the drop down list or enter a value of 1.

The adjacent lane to the right is a shared "hard" and "soft" left turn movement. To code this, select the appropriate picture from the drop down list or enter a value of 1 followed by pressing the [L] key to indicate a shared left movement. Use the same steps to code the movements with only one lane for the shared left turn movements (such as the NBL movement).

Right turns are entered in a similar fashion. For this example, the right turn movements are always shared with another movement. For example, the EBR lane is used for the "hard" and "soft" right turn movements. For the right turn movements shared with the through movement, such as the NB rights, the drop down picture only shows one right turn movement shared with the through lane. Synchro assumes that both the "hard" and the "soft" right turn are moving from this lane.

Additional items to be coded in the LANE settings:

• Use the defaults for Ideal Saturated Flow, Lane Width, Grade, Area Type, Leading Detector and Trailing Detector.

• Storage Length: Set the EBL and WBL to 250', all other lefts to 200'. Set the EBR and WBR to 150', all other rights leave as zero (no exclusive lane exists).

• Storage Lanes: Use the default calculated value.


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• Total Lost Time: In this case, the intersection created with six legs will be quite wide. This necessitates longer yellow and all-red periods. Therefore, the lost time will be increased. It is assumed a field study indicates that the Total Lost Time for the east-west is 5.5 seconds and 5.0 seconds for all other directions.

• Turning Speed: This setting is only used by simulation. However, since the angle for some turns is sharp and others are less then 90 degrees, these values should be updated. For all hard lefts, use 15 mph, 30 mph for soft lefts, 9 mph for hard rights and 25 mph for soft rights.

• Right Turn Channelized: For the EBR and WBR, set this field to 'Yield'. This will channelize the right turn and it will operate under yield control.

• Curb Radius, Add Lanes: Set the EBR and WBR Curb Radius to 20' and leave the Add Lanes as zero (0).

Change to the VOLUME settings and enter the hourly volumes shown above. Use defaults for all other values in the VOLUME settings.

To continue coding the required timing information for this intersection, see the following example on a Controller with More Than Nine Phases.


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Controller with More Than Nine Phases This example is a continuation of the previous example and will detail the steps to coding the appropriate timing information for a six-leg intersection with more than nine phases. To see the steps to create the network, see the previous example Six Leg Intersection.

Modeling with Synchro Filename: 6 Leg Intersection.syn

Step 3. Enter the Timing Data To enter timing date for a controller with more than nine phases, we will utilize the additional phase numbers set up (by default) in the Ring-and-Barrier-Designer. Phases 1 through 16 are available by default in the Ring-and-Barrier-Designer.

This example utilizes two rings (A and B) and three barriers (1, 2 and 3) for a total of twelve phases as shown in the graphic below. We will use the default phase numbers, therefore no revisions are required within the Ring-and-Barrier-Designer.

The phases in barrier 1 are the E/W Street movements, the phases in barrier 2 are the N/S Street movements, and the phases in barrier 3 are the Diagonal Street movements. All left turn phases are protected only movements.

Keep in mind that the operation above has three distinct barriers. In other words, phases in barrier 1 cannot operate with phases in barrier 2 or 3, phases in barrier 2 cannot operate with phases in barriers 1 or 3 and phases in barrier 3 cannot operate with phases in barrier 1 or 2. When all possible movement are allowed, as in the above example, signal operations become very inefficient due to the amount of time required to service all of the phases.

Next, enter the appropriate timing data. From the MAP view, click on the intersection E/W St. & Diag. St. and

activate the TIMING settings by pressing the TIMING settings button or the [F5] key. For this example, set the Controller Type to Actuated-Uncoordinated.

The next step is to enter the phase numbers for the individual movements. Starting in the Protected Phases row, enter the phase number(s) for the individual movements. For instance, the eastbound left movements (hard and soft lefts) operate as protected only lefts during phase 5. To code this, enter a 5 in the Protected Phases row for the EBL2 and EBL movements. The value in Turn Type will automatically update to Prot.

Continue entering the appropriate phases for the remaining movements. The resulting rows will appear as follows:


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Additional items to be coded in the PHASING settings are:

• Minimum Initial: Use a minimum initial of 10 seconds for all through phases and 4 seconds for all left turn phases.

• Yellow and All-Red: Due to the width of the intersection, longer clearance periods are necessary. For all east-west directions, use 4.5 seconds of Yellow and 2.0 seconds of All-Red. Use 4.0 seconds of Yellow and 2.0

• seconds of All-Red for all other directions.

• Walk and FDW: Pedestrians are allowed to cross all legs. For all even phases, use a Walk of 5.0 seconds. For phase 4 and 8 (SBT and NBT) use a FDW of 18 seconds. Use 11 seconds of FDW for all other phases.

• Ped Calls: Input ten (10) Pedestrian Calls for each pedestrian phase (even phases).

• Use the defaults for all other settings. The Minimum Split will be automatically calculated as the minimum of the Walk + FDW + YAR or the Minimum Initial + YAR. The cycle and splits will be determined in the next step.

Step 4. Optimize Intersection Cycle Length Now that the basic data is entered and analyzed, the next step is to find the best timing plan for this intersection. Use the Optimize→Intersection-Cycle-Length command to set the intersection to the Natural Cycle Length. The Natural Cycle length is the lowest acceptable cycle length for an intersection operating independently. Synchro will automatically optimize the intersection splits when you perform this step.


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T-Intersection with Non-Conflicting Pedestrian Movement In some instances, it may be desirable to allow pedestrians to cross a T-intersection during the non-conflicting main street left turn. For instance, the north/south pedestrians crossing the west leg of the T-intersection shown below can be allowed to operate with the westbound left turn movement. Note that the westbound through phase is not allowed to operate since it would be in conflict with the north/south pedestrian phase. The westbound left would be given a green arrow indication, the north/south pedestrian a walk indication, and all other movements would be given a red indication.

The figure below illustrates a single-ring phasing for a T-intersection with non-conflicting pedestrian phasing allowed with the main street left.

Phase 1 is the north/south pedestrian movement on the west leg. This phase operates in the presence of a north/south pedestrian call and is skipped in the absence of a pedestrian call.

Phase 5 is the westbound left turn (protected) with an overlapping northbound right turn. This phase operates in the presence of a westbound left turn call and is skipped in the absence of a westbound left.

Phase 2 is the westbound through phase. It is used as a "filler" phase in the presence of an eastbound left turn and the absence of a pedestrian call for northbound (phase 1).

Phase 3 is the eastbound/westbound through movement and the east/west pedestrian movement. It is called by the presence of an eastbound or westbound through vehicle or by a pedestrian actuation. This phase can be extended by


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the eastbound or westbound through movements. The eastbound right turn movement must yield to the pedestrian movement.

Phase 4 is the northbound left and right movements and is called and extended by the presence of a northbound vehicle. No pedestrian movements are allowed during this phase.

Modeling with Synchro Filename: T-Inter with non-conflict peds.syn


Use the defaults for all of the fields in the LINK SETTINGS window.

Step 2. Enter Lane and Volume Data From the MAP view, click on the intersection of Main Street & 1st Street and activate the TIMING settings by

pressing the TIMING settings button or the [F5] key. Enter the lane and volume data that is shown below (or see the Lane and Volume diagrams shown in Step 1):

To add more detailed information, such as turn bay lengths and peak hour factors, switch to the LANE settings and/or the VOLUME settings.

Step 3. Enter the Timing Data Remain in the TIMING settings [F5] to proceed with coding the example. For this example, set the Controller Type to Actuated-Uncoordinated.

The next step is to enter the phase numbers for the individual movements. Starting in the Protected Phases row, enter the phase number(s) for the individual movements. For instance, the westbound through occurs as a protected phase during phase 2 and also continues as a protected left during phase 3. To code this, enter a 3 in the Protected Phases row for the WBT, then insert a space [space bar] and enter a 2.


Continue entering the appropriate phases for the remaining movements. The resulting rows will appear as follows:


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The final step to setting up the timing data is to enter the split information. To do this, you can enter the value in the Total Split row. The Total Splits for this example are shown in the Total Split row in the above graphic. The Current Cycle Length is 100 seconds


The information required to perform an analysis of a T-intersection with non-conflicting pedestrians is now complete. To set phase specific parameters, such as the minimum split, yellow and red times, and pedestrian interval settings, see the PHASING settings.





Step 5. Optimize Intersection Cycle Length Now that the basic data is entered and analyzed, the final optional step is to find the best timing plan for this isolated intersection. Use the Optimize→Intersection-Cycle-Length command to set the intersection to the Natural Cycle Length. The Natural Cycle length is the lowest acceptable cycle length for an intersection operating independently. Synchro will automatically optimize the intersection splits when you perform this step.


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Florida T-Intersection The Florida T-Intersection is a special case where one of the main street through movements is allowed to operate continuously, even with the T-intersection left turn movement. Consider the following example:

In this case, the EBT movement is allowed to operate continuously, even during the SBL movement. The exception would be when a north-south pedestrian movement is allowed.

In this example, the SBL and EBT movements flow into there own lanes on the downstream (receiving) link. Often the movements are separated with a median and they are allowed to merge at some distance downstream.

Modeling with Synchro Filename: Florida T with peds.syn



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Open the LINK SETTINGS window for the east leg. For the EB direction, the travel lanes should be changed to '2'. Use the defaults for the remainder of the link settings.

Step 2. Enter Lane and Volume Data From the MAP view, click on the intersection of Main Street & 1st Street and activate the TIMING settings by

pressing the TIMING settings button or the [F5] key. Enter the lane and volume data that is shown below (or see the Lane and Volume diagrams shown in Step 1):

To add more detailed information, such as turn bay lengths and peak hour factors, switch to the LANE settings and/or the VOLUME settings. For this example, make the EBL turn bay 500' and the SBR turn bay 250'. Use defaults for all other values in the LANE settings and VOLUME settings.

Step 3. Enter the Timing Data Switch back to the TIMING settings [F5] to proceed with coding the example. For this example, set the Controller Type to Actuated-Uncoordinated.

The next step is to enter the phase numbers for the individual movements. For this example, the default Ring-and-Barrier-Designer can be used. The phase assignments are as shown below:

Starting in the Protected Phases row, enter the phase number(s) for the individual movements as indicated in the figure above. The items to note in this example are:

• The EBT uses phase 2 and phase 8. Phase 2 is entered in the Protected Phases row and phase 8 is entered in the Permitted Phases row. This indicates that the EBT should flow into its own lane on the downstream link. For instance, the EBT movement should flow into the curb lane of the receiving link and the SBL should flow into the median lane.

• Phase 7 is the pedestrian phase. Synchro and SimTraffic assume dual entry, therefore phase 8 will appear with phase 4 in the absence of phase 7 pedestrian calls.



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The resulting rows will appear as follows:

Next, switch to the PHASING settings. Set the Pedestrian Phase to 'Yes' for phase 7 and for phase 6. Use a Walk Time of 5 seconds, a Flash Don’t Walk of 11 seconds and set the Pedestrian Calls to 15. Use the default values for all other parameters in the PHASING settings.

Step 4. Optimize Intersection Cycle Length Now that the basic data is entered and analyzed, the final optional step is to find the best timing plan for this intersection. Use the Optimize→Intersection-Cycle-Length command to set the intersection to the Natural Cycle Length. The Natural Cycle length is the lowest acceptable cycle length for an intersection operating independently. Synchro will automatically optimize the intersection splits when you perform this step. The resulting Splits and Phasing Diagram will appear as shown below:

Filename: Florida T no peds.syn

It is also possible to have a situation where the EBT phase is always continuous, that is, there is no north-south pedestrian phase. Refer to the file 'Florida T no peds.syn' for an illustration. In this case, phase 2, 7 and 8 are not used. To do this, the EBT is coded as 'Free' in the Permitted Phases row. The TIMING settings rows will appear as follows:


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Arterial with Wide Median Example In the past, it has been difficult to model intersections with wide medians using existing traffic engineering software packages. The issue is that the wide median creates two intersections that are required to operate with one controller. Synchro will allow you to directly model such situations.

One example of an arterial with a wide median is for that of a Michigan left configuration. An example lane configuration for a Michigan left is shown below.

Notice that left turns are not allowed off of the mainline onto the side street or off of the side street onto the main line. To do this, the vehicles must first turn right and then make a U-turn at the median break some distance from the intersection (660 feet in this example).

This U-turn movement can either be signalized or unsignalized. For this example, it is assumed that the U-turn movements are signalized. This creates four signalized intersections that may be operated with one controller.

Filename: Mich Left.syn

Step 1A. Create the Network To begin a new network, open Synchro and select the command File→New. From the MAP view (press [F2] if not already in the MAP view), create the network shown below (see the topic on Mapping out Links and Intersections). The north-south distance between the Main Street Arterials is 100 feet. The distance from the center intersection to the U-turn intersections is 660 feet.

To draw short links, use the Options→MAP-Settings command to reduce the width of the links and the radius of the nodes. Also, zoom in on the area where the network will be created to give more precision when creating links.


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In the LINK SETTINGS window, set a speed of 55 mph for Main N and Main S, 40 mph for the Side Street and 30 mph for the U-Turn movements. Use the defaults for all other fields in the LINK SETTINGS window.

Step 1B. Enter Lane and Volume Data From the MAP view, click on one of the intersections and activate the LANE settings by pressing the Lane View

button or the [F3] key. Enter the following lane data for the network (use the defaults for values not shown):

Node EBL EBT EBR WBL WBT WBR NBL NBT NBR SBL SBT SBR

Lanes and Sharing 1 1 3




Storage Length (ft) 2 200 250

Storage Lanes (#) 2 1 1




Storage Length (ft) 3

Storage Lanes (#) 3

Leading Detector (ft) 3 475 50

Trailing Detector (ft) 3 234 0


Storage Length (ft) 4

Storage Lanes (#) 4

Leading Detector (ft) 4 475 50

Trailing Detector (ft) 4 234 0


Storage Length (ft) 5 200 250

Storage Lanes (#) 5 1 1







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Next, switch to the VOLUME settings by pressing the Volume View button or by pressing [F4]. At each intersection, enter the volumes as shown in map figure at the start of this example. Use the default values for Conflicting Peds, Growth Factor, Heavy Vehicles, Bus Blockages and Adj Parking Lane. Use a Peak Hour Factor of 1.0.

Step 2. Select a Controller Scheme The next step is to choose between Local and Group control and between fixed and floating cycle length. For more details, see the Signal Timing Background chapter on the topics Group Control versus Local Control and on Fixed Cycle Length versus Floating Cycle Length.

In many cases the decision whether to use Local or Group control will depend on the existing signal equipment. Unless you are working on new construction or a major update, the timing plans must be generated to match the existing equipment.

For this example, all of the intersection will operate with Group Control.

Step 3. Set up Phasing As noted in step 2, the intersections in this example will all work with one controller. To attach the intersections, use the Cluster Editor. Select the intersection of Side Street & N Main (node #2) and switch to the TIMING settings.

Press the [Options] button and select Cluster Editor.

Click on the intersection of Side Street & S Main to add this intersection to the cluster. Next, click on the intersection of Main Street & W U-Turn then the intersection of Main Street & E U-Turn. All four intersections should now be connected with on controller.

Notice that the color for the attached nodes has changed. This color will be used in the TIMING and PHASING settingss to clearly define which intersection data is being modified.

Select [OK].

For the Michigan left, it is desired to have the vehicles on the main street leave the U-turn and arrive at the center intersection when the main street is changing to green. When the main street green at the U-turn terminates, the center intersection should remain green for a period of time to allow vehicles to proceed. Also, there should be some time when the interior (median) movements in the north-south direction remain green to clear out the internal space.

To do this, the ring and barrier structure for the controller needs to be set up. Switch to the Ring-and-Barrier-Designer for each intersection. Set up the Ring-and-Barrier-Designer as shown below:

Phase 2/6: Node 5 EBT (phase 2) and Node 2 WBT (Phase 6). Set the Recall to None and the Minimum Initial to 15 seconds. Use defaults for other values.

Phase 4: Will be used as node 2 NBT and Node 5 SBT. These are the internal through movements.

Phase 8: Will be used as node 2 SBT and Node 5 NBT. These are the external movements. Set the All-Red Time to 6 seconds. Notice that this will allow the external movements to terminate prior to the internal movements (phase 4). This will ensure that the space in the median is cleared out.

Phase 1: Node 3 and node 4 EBT and WBT. This phase is active when phase 2/6 begin.

Phase 5: Node 3 and node 4 U-turn movement begins. Phase 5 is 8 seconds long. This is the time when the EBT and WBT at the U-turn terminates and phase 2/6 continue to stay green


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Phase 3: Node 3 and node 4 U-turn movement. This is another phase to allow the U-turn to cross into barrier 2.

Phase 7: Node 3 and node 4 EBT and WBT begins. This phase is 8 seconds long.

Node 1 and 6 should be set-up as unsignalized intersections with ‘Free’ set for Sign Control.

With the RB set up for each intersection, switch to the TIMING settings and enter the appropriate Protected Phases and Permitted Phases as shown below.

The Vehicle Extension and Minimum Gap for the East-West movements should be set to 3.2 seconds. This is 111% of the travel time required to get from the last extension detector to the stop bar. All Pedestrian Phases should be set to ‘No’. Use defaults for all other values.

Step 4. Optimize the Network The final step is to optimize the intersection cycle length. To do this, use the command Optimize→Intersection-Cycle-Length. The Splits will be automatically optimized with this step. Reset phase 5 and phase 7 to 8 seconds.


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Fixed Cycle Coordinated System The sample problems up to this point have assumed isolated intersections. In reality, many signalized intersections are in a network or system of other signalized intersections. In this example, the elements of a fixed cycle, coordinated system will be investigated.

Filename: Fixed Cycle Coordination.syn

Step 1. Create the Network To begin a new network, open Synchro and select the command File→New. From the MAP view (press [F2] if not already in the MAP view), and create the network shown below (see the topic on Mapping out Links and Intersections). For purposes of this example, it is assumed that you have previously created the intersection networks in the prior examples. Creating a system of intersections is simply connecting a series of isolated intersections.

Step 2. Enter Lane and Volume Data Lane and volume data can be entered in the TIMING settings or within the particular windows for that purpose (LANE settings or VOLUME settings). For this example, it is assumed the user has reviewed the previous examples and is comfortable at entering this data.

Step 3. Enter the Timing and Phasing Data Timing data is entered in the TIMING settings and phasing data in the PHASING settings. See the previous examples and the appropriate topics in Synchro for detailed information on entering this data.

Step 4. Optimizing the System The next step for creating signal timing plans for a network of intersections is to optimize the system.

Step 4A. Partition Network This step is used to divide the network into subsystems and is optional. It is up to engineering judgement to decide whether to partition a network.

The Partition Network command will divide the network into multiple zones. This function assigns a zone name to each intersection. Each zone can be optimized as a separate system in the cycle length optimization.

To partition the Network, use the Optimize-Partition-Network command.

For this example, use the ‘Divide Sometimes (50)’ option. This will group intersections with a Coordinatability Factor (CF) greater than 50.

After partitioning the network, view the zones by pressing the Show Intersection Zones button . Synchro has recommended that all of the intersections are placed within one zone (All CF’s are > 50).

Step 4B. Optimize Network Cycle Length The next step is to determine a system cycle length. Use the Optimize→Network-Cycle-Length command to do this. The following dialog box appears:


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Use a cycle length range from 80 to 150 with 10 second increments. For Allow Uncoordinated, select ‘Never (0) since this step has already been performed in Step 4A. Do not allow half cycles. Do not preserve files for each cycle length. Use an Extensive offset optimization (a more detail offset optimization will be performed in step 4C) and set the Scope to ‘Entire Network’. Select [Manual] to begin the cycle length optimization. By using the manual option, Synchro will display a table with the PI for each cycle length evaluated.

As Synchro is optimizing, the 'Optimizing Cycle Length status box will be displayed.

Upon completion of this process, the SELECT CYCLE LENGTHS window will appear.

In this example, a cycle length of 110 gives the smallest (best) Performance Index (PI). Press [OK] to accept the 110-second cycle length for the intersections in the system.

To check the cycle length with a smaller increment, now perform the above procedure with a cycle length increment of 5 seconds with a minimum cycle of 105 and a maximum of 115. This time also use the Preserve Files for Each Cycle Length option. This still results in a cycle length of 110 seconds.

Step 4C: Optimize Offsets, Lead-lag Phasing After determining a system cycle length, the last step is to optimize offsets. Use the Synchro command Optimize→Network-Offsets. The following dialog box will appear:


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For this example, use the existing splits, allow lead/lag optimize, use the ‘Best Timing Plans’ option and set the Scope to ‘Entire Network’.

This completes the optimization process of a network with fixed cycle lengths.


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Two Way Traffic Control The Two Way Traffic Control example is a special case where only one direction of traffic is allowed to operate at one time. A common application would be traffic control on a two-lane bridge or tunnel where one lane is closed, or the bridge is wide enough to accommodate one direction of traffic.

In this example, an east-west segment will be modeled where only one direction of traffic will be allowed at one time. 'Dummy' signals will be placed at each end of the bridge. This will be done with a simple two-phase signal that allows one direction at a time. Synchro allows the user to model a very long all-red period between the phases to clear the space between the two signals.

Modeling with Synchro Filename: Two Way Traffic Control


The distance between Dummy Signal 1 and Dummy Signal 2 is 1070 feet. Use the default setting in the LINK SETTINGS window for each of the links. Use the node numbers shown in the graphic above.

Step 2. Enter Lane and Volume Data From the MAP view, click on the intersection of Bridge Road & Dummy Signal 1 and activate the TIMING settings

by pressing the TIMING settings button or the [F5] key. Enter the lane and volume data that is shown in the graphic from Step 1. Do the same for Bridge Road & Dummy Signal 2.

To add more detailed information, such as turn bay lengths and peak hour factors, switch to the LANE settings and/or the VOLUME settings. For this example, use defaults for all other values in the LANE settings and VOLUME settings.

Step 3. Set up Group Control In this example, the two intersections will operate under group control. To attach the intersections, use the Cluster Editor. Select node #1 and switch to the PHASING settings (or the TIMING settings).


Click on node #2 to add this intersection to the cluster.

Notice that the color for node #2 has changed. This color will be used in the TIMING and PHASING settingss to clearly define which intersection data is being modified.

Select [OK].


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Step 4. Enter the Timing Data Switch back to the TIMING settings [F5] for intersection 1 to proceed with coding the example. For this example, set the Controller Type to Actuated-Uncoordinated.

Starting in the Protected Phases row, enter the phase number(s) for the individual movements. For the EBT direction, enter '1' for the Protected Phase. For the WBT Protected Phase, enter 'Free'. This will allow the WBT vehicles to operate with 100% green, and they will never have to stop.

Switch to the TIMING settings [F5] for intersection 2 and enter '2' for the WBT Protected Phase and 'Free' for the EBT Protected Phase.

The listed phases will become the Detector Phases.

Other items to code this example:

• Use a Cycle Length of 160 seconds.

• Set the Total Split for phase 1 and phase 2 to 80 seconds.

• Use an All-Red time of 40 seconds for both phase 1 and 2. This is the clearance time between the two dummy intersections. This will allow vehicles to clear the space between the ends of the bridge.

• Set the Minimum Initial to 6.0 seconds for phase 1 and 2.

• Switch to the PHASING settings. Set the Pedestrian Phase to 'No' for phase 1 and 2.

• If desired, set the Recall Mode to 'min' for one or more of the phases. This will ensure that one phase will be recalled without the presence of a vehicle demand. If no phase is placed on recall, the signal will rest in red without vehicle demand. For this example, phase 2 is placed on minimum recall.

Now you can simulate this example by clicking on the SimTraffic Animation button or press [Ctrl]+[G] to start SimTraffic. You will notice that only one direction of traffic is allowed to operate at one time.


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Roundabouts (Simulated) SimTraffic now has the capability to model roundabouts. In this example, the curved link example will be used to create a multi-lane roundabout.

Modeling with Synchro Filename: Roundabout.syn


This is an extension of the previous curved link example. Begin with the file that was created in this previous example, or open the file Curved Link.syn. Be sure to save the curved link file with a new name before modifying.

The distance between the ramps is 800 feet. Use the default setting in the LINK SETTINGS window for each of the links.

Step 2. Enter Lane, Volume and Signing Data From the MAP view, click on the SB Ramp & Main Street intersection and activate the TIMING settings by

pressing the TIMING settings button or the [F5] key. From the Controller Type, choose a roundabout. A message will appear indicating that Synchro will only model a single lane roundabout. However, SimTraffic will fully simulate multi-lane roundabouts.

Enter the lane, volume and signing data shown below.

Use an Inside Radius of 28', an Outside Radius of 40', set the Number (#) of Lanes to 1 and leave the Speed Limit as 18 mph. The Inside Color can be changed by clicking on the colored circle if desired.


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Notice that only 1 lane for the approach is added and shared turn movements are not shown in the Lanes and Sharing row. If volumes are entered, then Synchro and SimTraffic will assume that the traffic is shared with the lane. It may be easier to understand if coded this way since the turns are not 'traditional' turns.

Select the NB Ramp & Main Street and set this to a Roundabout within the TIMING settings/Signing Window.

Enter the lane, volume and signing data shown below.

Use an Inside Radius of 30', an Outside Radius of 54', set the Number (#) of Lanes to 2 and leave the Speed Limit as 18 mph. The Inside Color can be changed by clicking on the colored circle if desired. In addition, the WB and SB approaches have a Two Lane Exit. Refer to the SimTraffic Help file for an example on how this will act in the simulation (or simulate the sample file to see for yourself).

From the MAP view, double click on the link to the north of the NB ramp. Enter 2 for the NB Travel Lanes. Do the same for the EB link to the east of this intersection.

Activate the LANE settings by pressing the Lane View button or the [F3] key. The EBL and the NBR have a storage of 150'.

Now you can simulate this example by clicking on the SimTraffic Animation button or press [Ctrl]+[G] to start SimTraffic.

In addition:

• If multiple runs in SimTraffic are desired, this can now be done with the Record Multiple Runs option.

• The SimTraffic reports, check the Multiple Runs box in the SELECT REPORTS window and you will have the option to average multiple history files.


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Channelized Right Turns Synchro and SimTraffic can model channelized right turns (often referred to as pork chop islands). In this example, the Basic Two-Stage Isolated Intersection example will be used as the starting point.

Modeling with Synchro Filename: Basic 2P w Porkchops.syn (to see the completed network)

Step 1. Create the Network The network for this example is already created. Open the file Basic Two-Stage Isolated Intersection.syn. Perform a Save-As to rename the file to a new name. A taper will be required 400' to the east of node 3. To do this, select the

Add Link button or press the [A] key. Start at node 3 and draw a new link of 400' long directly on the existing node 3-2. A bend node will be placed at the location where you click to stop drawing the link. This has simply divided link 3-2; it has not created a new link on top of it. Double click on the link between node 3 and the new bend node. Enter 3 for the number of Travel Lanes in the EB direction.

Step 2. Enter Lane and Volume Data From the MAP view, click on the intersection of Main Street & 1st Street and activate the LANE settings by

pressing the Lane View button or the [F3] key. Most of the data in the LANE settings was created for the previous example. Modify to add two (2) WBT and EBT lanes. In addition, code the channelized right turn information as follows:

The EBR is an example of an exclusive channelized right lane where a SB receiving lane is added. In Synchro, this will be treated as a free flow movement with 100% green time.

The WBR is an example of an exclusive right that directly merges into the NB lanes. The WBR vehicles will yield to the NB vehicles.

The NBR shared right becomes an exclusive add lane in the EB direction. The lane will taper back to two lanes at the downstream bend node.

The SBR illustrates a shared right that is divided by an island (small) but is under signal control. There is not a downstream add lane.

The data in the VOLUME settings does not need to be updated.

Step 3. Enter the Timing Data The data in the TIMING settings does not need to be updated.

Step 4. Optimize Intersection Cycle Length Now that the basic data is entered, the next step is to find the best timing plan for this isolated pretimed intersection with pork chop islands. Use the Optimize→Intersection-Cycle-Length command to set the intersection to the Natural Cycle Length. The Natural Cycle length is the lowest acceptable cycle length for an intersection operating independently. Synchro will automatically optimize the intersection splits when you perform this step. The resulting cycle length is shown in the Current Cycle Length field show on the left of the TIMING settings.


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Step 5. Interpreting Results The final step is to interpret the measures of effectiveness (MOE) for the example. The most common MOEs are shown in the TIMING settings rows for each lane group.

The intersection wide MOE's for maximum volume to capacity (v/c) ratio, delay and level of service (LOS) are shown in the left side of the TIMING settings.

The v/c Ratio is calculated using actuated green times and cycle lengths. The v/c Ratio indicates the amount of congestion for each lane group. Any v/c Ratio greater than 1 indicates the approach is operating above capacity.

The delay is a measure of the Total Delay, in seconds per vehicle, experienced for the given lane group. Version 6 introduced two new delay measurements. In addition to the traditional Control Delay, Synchro also includes a Queue Delay. The Total Delay is the combination of the two types of delay.

The LOS is a means of describing the operational efficiency of a given intersection based on the calculated delay. The range of service quality has been defined in terms of six LOS ranges (A to F). LOS A represents free flowing conditions with insignificant delays. LOS F represents forced flows (jammed conditions) with excessive delays. Under LOS F, queues may block upstream intersections.

To quickly print these results, use the command File→Print-Window. For other more detailed reports, see the topic on Intersection Reports.

Now you can simulate this example by clicking on the SimTraffic Animation button or press [Ctrl]+[G] to start SimTraffic.

In addition:

• If multiple runs in SimTraffic are desired, this can now be done with the Record Multiple Runs option.

• The SimTraffic reports, check the Multiple Runs box in the SELECT REPORTS window and you will have the option to average multiple history files.

Documents

Synchro Studio Examples