Complete Street Design Guideline: “Chicago”

Sabrena Jahan OhiStudent ID: 15RB903

M1 StudentTransportation and Urban Engineering Laboratory

Chicago is the third most populous city in the United States and the most populous city in the state of Illinois with nearly 10million people

Chicago's streets were laid out in a street grid that grew from the city's original town site plat. A scattering of diagonal streets, many of them originally Native American trails, also cross the city.

Chicago's Western Avenue is the longest continuous urban street in the world.

Chicago

Complete Street Chicago

Modal Hierarchy

•Vulnerable group•Downtown, Commercial/ entertainment area has high volume of pedestrian

•Even if not dominant user, still need to provide facilities

•Facilities must comply with ADA

Pedestrian•Provide access to essential services, jobs and reduce automobile demand

•Size and characteristics of bus operation influence street design

•Access and volume at train stations affect design

Transit•Complete street must accommodate cyclists

•Vulnerable user•Faster than pedestrian but slower and less visible than automobile

•Critical link in city’s freight network

Bicycle•Accommodated with constraints of lower speed and prudent driving

•Commercial vehicles are given preference to ensure economic sustainability

Auto

Design Trees

Cross Sections

Label Code=Mode. Building,Roadway

Modal Hierarchy

Building Typology

Roadway Typology

ROW widthTarget Speed

Volume = ADT

Design Trees

Design Trees: Roadway Form and Function

Truck/ Bus lane 11 feet

Auto/bike Shared lane 14 feet

Combination of travel and parking no less than 18 feet (11’ +7’)

Typical parking lane width 7ft

Curb extension = width of parking lane – 1~2 feet

Neighborhood streets lanes are not usually marked

Frontage lane is the side travel lane of multiway thoroughfare

* All dimensions are in feet

Cross-Section Elements

Cross-Section Elements1.Curbs:Prevent water and cars to encroach on sidewalk2.Bicycle Facilities:Separate cyclist from both pedestrian and carsAccommodate both faster cyclists and leisure

riders3.Onstreet Parking:Supports storefront retail, slows moving traffic,

and protects people from errant drivers and fast moving traffic.

Space is valuable real estate that can be used. Problematic for cycling due to the increase

chance of being “doored” or cars idling in the travel lane waiting for a parking space to become available.

Does not make a street more or less complete so If used careful design is required

Interstitial Area

1.Frontage Zone:The area between the walkway and building,

fence or yard.The edge of the right of way.For front lawn with no fence zone width is

zero2.Walking Zone:Area dedicated to walking. Must be straight and continuous with ADA-

compliant and clear of all obstructions.Pedestrian volume influence zone width3.Sidewalk Furniture Zone:Located between curb and walking zoneTo make walking zone free from obstruction

Pedestrian Realm

Cross-Section ElementsMedian

1.Bus Lanes:Exclusively used by BusForm varies from rush-

hour only lane to physically separated lane

For existing street, either convert auto lanes or remove parking; do not widen roadway

If shared with bicycle, special measures must be taken

2.Travel Lanes:Used by automobile, bikes

and transitProvide minimum

number of lanes

Vehicle Realm

Intersections: Layout Most pedestrian crashes in Chicago occur within 125 feet of an intersection

Some complex intersections are a result of poor street connectivity

Connectivity

Excessive pavement need to be minimized to reduced crossing distances and increased ecological functionality.

PossibleCurb Extension

Excessive pavement

Compact ones have three or four legs and right angles.

Complex ones are with multiple legs, traffic islands, skewed angles, and/or turn lanes.

Intersections should be as compact as possible but if not possible, separate traffic flows with islands and traffic control devices.

Reconfiguring is made by converting an X-intersection into two T-intersections or squaring off Y-junctions.

More compact intersections are preferable to fewer, complex ones.

Compact vs Complex

Intersections: Layout

Intersections: Corner Design

Turning speed •15 mph or less for passenger vehicles•R = V2/15(0.01 E + F) R = centerline turning radius (effective)V = speed in miles per hour (mph)E = super-elevation; 0 in urban conditions.F = side friction factorEffective Radius and All Lanes•To find the path of large vehicles traversing the intersection, and the turning speed of passenger vehicles•The effective radius is typically not the same as the corner radius•CDOT minimizes intersection size with smaller corner radii, set back stop lines, and other techniques•A large corner radius should not be used to facilitate a truck turning from the right lane into the right lane.Design and control vehicle•Select smaller design vehicle over larger intersection

Right/Left turn on Red•Can be prohibitedTurn Lanes •Right turn lanes are to be avoided as they widen the roadway and facilitate higher turning speedsSlip Lanes•Provided after network analysis and intersection minimizing with Compliance committee approval•Complimented with stop control and a raised crosswalkHighway Ramps•Need to slow drivers down from highway to street speeds before they arrive to the intersection.

A crosswalk is the extension of the sidewalk or walking area across the road. Pedestrians cross the street at a variety of locations Within the City of Chicago, pedestrians have the right-of-way at crosswalks unless

directed otherwise by traffic-control devices, police officers or traffic control aides.

Intersections: Pedestrian Crossings

Facility Selection Methodology

The crossing treatment is largely a function of automobile speed, automobile volume, roadway configuration.

Multi-lane, high-speed, and high volume roads require more aggressive treatments such as lane narrowing, medians, overhead signs, and advance stop lines.

Traffic control devices such as crosswalk striping, yield signs, and signals may be warranted

Treatment

Located where pedestrians want to cross, and where drivers can reasonably expect pedestrians to cross.

People generally cross where it’s most convenient, in as direct a line to their destination as possible. This is known as the desire line.

Locate according to the walking network, not the driving network.Crossings should be provided where an analysis shows a concentration of origins and

destinations directly across from each other.Site design and landscaping can orient people to preferred crossings,

Location

Intersections: Pedestrian Crossings

Intersections: Pedestrian Crossings

•After setting the location and type, the crossing can be designed.

•People crossing at corners need protection from turning drivers

•Crosswalk width ≥ sidewalk width•Pedestrian ramps should be equal to the size of the crosswalk

•Marked crosswalks should not be longer than three lanes.•Unsignalized marked crosswalks shall be lit as brightly as a signalized intersection

•A median or refuge island allows a person to cross one direction of traffic at a time, making it much easier to find and correctly identify acceptable gaps.

•The preferred width of a pedestrian refuge is eight to 10 feet with the minimum protected width is six feet

•Medians and refuge islands should include curbs, bollards or other features to protect people waiting.

•The cut-through or ramp width should equal the width of the crosswalk.

•Vertical elements such as trees, landscaping, and overhead signage identify the island to drivers

Design and Operation

Intersections: Driveways

Ramp the driveway up to meet the sidewalk

Carry the sidewalk grade and surface material across the driveway.

Smallest dimension is to be attained

Design speed 10 mph. 90 degrees orientation with the

street. Stop/yield signs for exiting traffic

with limited sight distance Minimum number to be designed

for reduced conflict Instead of driveway, utilizing an

alley is recommended by locating the buildings along the street and parking along the alley

Geometric & Operational Policies: Level of Service

Motor Vehicle Level of Service (MVLOS) assesses delay for motorists along a roadway section or at a signalized intersection (Scale: A to F)

MVLOS does not consider other modes or goals such as safety and convenience.

LOS should be consistent with modal hierarchy.

The maximum MVLOS for CDOT-initiated projects shall be E.

LOS evaluations shall consider cross flows as well as corridor flows.

Delay for pedestrians at signals shall not exceed 60 seconds with minimum sidewalk LOS B

LOS evaluation with multi-hour evaluations instead of peak-hour only is encouraged

Pedestrian facilities ≫ Edge - building, setback, fence, open space ≫ Walkway - window shopping, vending, cross-flows ≫ Sidewalk furniture - cafe seating, trees, bicycle, bus stops ≫ Corner - queuing, accessibility ≫ Interference - driveways, alleys, parking, deliveries,

Transit facilities ≫ Headways ≫ Stops - amenities, spacing ≫ Interference - turns, deliveries, parking ≫ Bicycle facilities ≫ Separation, from pedestrian realm and roadway ≫ Guidance and prioritization, especially at conflict points ≫ Interference - turns, deliveries, parking

Automobile facilities ≫ Volume fluctuation - peak hour and off peak, weekday and

weekend, seasonal ≫ Loading and parking - coordinated with volume fluctuation ≫ Peak-hour operational issues - transportation demand

management, signal synchronization ≫ Interference - pedestrian crossings,

bicycle operations

Considerations

Geometric & Operational Policies: Traffic Control Devices

1. Synchronized signals are preferred and shall be set at or below the target speeds2. Signal timing shall be adjusted during off peak hours to manage automobile speeds.3. Fixed time signals are the preferred option. 4. Left turns should occur after the through movement (lagging).5. All legs of all signalized intersections shall have marked crosswalks unless pedestrians are

prohibited from the roadway 6. “NO PEDESTRIANS” signs need to be accompanied by a physical barrier and positive

information about where pedestrians are to walk and/or cross the street.7. Leading pedestrian intervals will be installed as per Chicago Pedestrian Plan. 8. Signals on transit-priority roadways should be timed to prioritize transit, 9. Signals on bicycle-priority roadways should be timed for bicycle commute speeds (15 mph),

Policy

All traffic control devices shall support the complete streets modal hierarchy.

A well designed intersection can be made unusable by many if the signal is optimized for automobile flow.

Too many stop signs can make a roadway seem like a driving gauntlet. The lack of traffic control, especially at minor intersections, may make it

impossible for people who wish to cross the street.

Geometric & Operational Policies: Turns on Red & Lane Width

While Right or Left Turns on Red (RTOR, LTOR) are legal in the City of Chicago; they are a privilege, not a right.

Turns on Red (RTOR, LTOR) adversely impact pedestrian comfort and safety.

Pedestrian safety at transit stops is compromised when drivers turn while people are crossing the street after getting off the bus.

Right turns on red also restrict bicycle travel. If accommodating turns on red adversely

impacts the design, the turn will be prohibited

Turns On RedConverting 10 feet lanes into 12 feet •On a six lane roadway has great impact as this equals another lane, two bike lanes, a wider sidewalk, on-street parking, or a median.•Increased crossing affecting signal timing. Higher travel speeds •No improvement in safety

Policy•The standard lane width 10 feet•One lane per direction on scheduled Chicago Transit Authority (CTA) bus routes and/or on a mapped truck route may be 11 feet wide.

≫ Thoroughfare: 10-11feet ≫ Connector: 9-11 feet ≫ Main Street: 9-10 feet ≫ Neighborhood Street: n/a

Lane Width

Geometric & Operational Policies: Design & Control vehicles

Design VehicleThe design vehicle influences several geometric design features including lane width, corner radiiLarger ones increase turning speed and crossing distancesSmaller ones result in frequent instances of trucks driving over curbs on street corners, endangering pedestriansIt is best to err on the side of too small than too large for urban setting.Design vehicles for different roadway typology≫Thoroughfare: WB-50

≫ Connector: BUS-4035 ≫ Main Street: SU-3036 ≫ Neighborhood Street: DL-23 ≫ Service Way: DL-23

Delivery Van (DL-23) Length 23 feet, Width 8.5 feet (10 feet with mirrors), Height 10 feet with turning radii 29 feet outside, 23.3 feet centerline, and 22.5 feet inside

Control Vehicle•The design vehicle keeps an intersection compact for everyday use, the control vehicle allows access by necessary vehicles.•A control vehicle utilizes all traversable parts of an intersection, including driving over curbs and across centerlines for emergency access

Geometric & Operational Policies: Design & Target Speed

• Design speed is set as high as practical, usually over the speed limit

• For complete streets, CDOT will use target speeds instead of design speed, where the design and operation of a street is set to induce drivers to drive at or below the speed limit. ≫ Thoroughfare: 25-30 mph ≫ Connector: 20-30 mph ≫ Main Street: 15-25 mph ≫ Neighborhood Street: 10-20 mph ≫ Service Way: 5-10 mph

Speed control elements are often necessary to maintain target speeds Signals synchronized to target speedNarrower lanes, especially on Main Streets, Neighborhood Streets and Service WaysRoadway physically narrowed through bicycle facilities, on-street parking, raised medians/islands, curb extensionsTraffic calming devices like speed humps, mini-roundabouts, chicanesLimited sight distance such as buildings on the cornerTerminating vistas, such as at a T-intersection or at a traffic circle. When drivers cannot see to the horizon, they tend to driver slower.Rhythms created with trees, poles, landscaping, and crosswalks

Conclusion Complete street design requires:i. Directionii. Observationiii. Iteration Tenets of Street Design1. Vehicle speed optimization2. Exposure risk minimization3. Behavior prediction of all mode user

Although freight and goods delivery is an important part of Chicago’s streets, It is not included as a specific mode because it is cross modal- trucks (auto), bike trailer (bicycle), and delivery person (pedestrian).

Project-specific alternative hierarchies may be submitted for Compliance Committee approval.

• Along a major transit corridor: Transit > Pedestrian > Bicycle > Automobile • Along a bicycle priority street: Bicycle > Pedestrian > Transit > Automobile