ROADWAY INFORMATION MANUAL Chapter 2 · ROADWAY INFORMATION MANUAL Chapter 2 – Roadway Data Overview (January 2013) Data Events and Attributes Cardinality Inventory Direction All

ROADWAY INFORMATION MANUAL Chapter 2 (January 2013)

LRS Geometry

NLF_ID

ROADWAY DATA OVERVIEW This Chapter explains how Ohio DOT references its roadways for field data inventory and database processing in the Roadway Information System. After collection, roadway data is stored in the following databases:

• LRS Events Table

• LRS Segments Table

• DESTAPE Table

• Ramps and interchanges table (currently incomplete).

The Department conducts inventories of the roadway data elements for the State-owned System (Interstate, U.S., State Routes) and Off-State System (County, Township, Municipal routes). The data collection processes are described in Chapter 5.

Ohio’s roads are represented as segments in ODOT’s RIS and have associated data elements that describe roadway geometrics and characteristics. All road segments are identified with a unique key database field, called NLF_ID, through which attribute data elements can be linked.

Through NLF_ID, map layers can be created statewide, by county or local jurisdiction, and by route system and number. NLF_ID is a combination of seven components from the LRS Segments attribute table that describes administrative and other characteristics related to a route segment. Following is a breakdown of the components by position in the code string:

Position 1 (TRANS_JURISDICTION_CD attribute): Primary legal authority of transportation facility:

S – State C – County T – Township M – Municipal F – Federal P – Private X – Unknown

Positions 2-4 (COUNTY attribute): Standard ODOT three letter abbreviation of Ohio’s county names. These codes are listed in the COUNTY Attribute sheet (see Chapter 3, Page 18). Examples are:

ADA – Adams, ALL – Allen, ASD – Ashland, etc.

SDARSR00049*AC

Chapter 2 – Page 1

ROADWAY INFORMATION MANUAL Chapter 2 – Roadway Data Overview (January 2013)

Positions 5-6 (TRANS_ROUTE_CD attribute): Basic transportation grouping or system that the facility belongs to:

IR – Interstate US – United States Route

SR – State Route CR – County Road TR – Township Road MR – Municipal Street RA – Ramp NR – Natural Resources Road (Park Road) FR – Forest Road BK - Bike Route (Trail) RE – Rest Area Entry/Exit WS – Weigh Station Entry/Exit RR – Rail Road Track DD – Department of Defense Road NP – National Park Service Road FW – National Fish and Wildlife Road NA – NASA Road CN – Connecting Road DR – Driveway PL – Parking Lot XX – Unknown

Positions 7-11 (TRANS_ROUTE_ID attribute): Transportation route identification is assigned by TIMS. Each State system route number is unique within the entire state. Local Roadways are unique within a given county. Right justified, left filled with zero:

00071 – Interstate 71, 00040 – U.S. 40, 00161 – State Route 161, etc.

Position 12 (TRANS_ID_EXTENSION attribute): This field is an extension of the TRANS_ROUTE_ID. It differentiates routes that would otherwise have the same number:

County Route 1 – has no extension, and is coded with a placeholder character (‘*’) County Route 1A – has extension, and is coded as ‘A’

For the above examples, Positions 7-12 for County Route 1 in Stark County would be coded as CSTACR00001**C; Positions 7-12 for Stark County Route 1A would be CSTACR00001A*C.



Example Code

Position 13 (TRANS_ID_DESCRIPTION_CD attribute): Defines a specified characteristic of the transportation facility. Each alpha character has a specific meaning:

* – Default (regular route) A – Alternate B – Bypass C – Spur or Connector D – Directional Alternate (1st within county) E – East Bound F – Directional Alternate (2nd within county) G – Directional Alternate (3rd within county) I – Interchange Roadway J – Waiting for final disposition (abandonment or transfer) K – Turnpike N – North Bound P – Proposed (not built) S – South Bound T – Temporary Route W – West Bound

Position 14 (TRANS_BI_DIRECTIONAL_CD attribute): All roadways in Ohio are inventoried based on cardinality, inventoried from south to north and west to east. This code was developed for future use as ODOT implements inventory systems that can have dual centerlines, such as an Interstate highway. Coding of this attribute is as follows:

C – Cardinal direction, N – Non-cardinal direction. Default is C.

Below is a diagrammatic example of an NLF_ID code for State Route 49 Alternate in Darke County. This code is represented by the code string SDARSR00049*AC.

Pos 1: Primary Legal

Authority

Pos 2-4: County Name

Abbrev.

Pos 5-6: Group or system

Pos 7-11: Route

Identification

Pos 12: Route Suffix

Pos 13: Specified

Characteristic

Pos 14: Inventory Direction

S DAR SR 00049 * A C



Standard Logmile Measures

Route Measures Measurements of a roadway inventory segment are specified in logmiles. Events and attributes may run for the entire length of the NLF_ID segment or for specific portions (e.g. from logmile 0.345 to logmile 1.234). This information (logmiles, side of road, etc.) is found in the Events/Attributes datasets.

The beginning logmile of a segment is set within each county, typically from the county line or intersection with another roadway. Logmiles follow the accumulated mileage along the road within a county, with their locations expressed in miles to three decimal places (1/1000 of a mile). The ending logmile is reached when the route exits that county, ends at an intersection, or otherwise dead-ends.

Figure 2-1 illustrates this “standard” situation.

Figure 2-1: Logmiles for Routes - Standard Example



Route Overlaps Logmiles for an NLF_ID segment usually start at a beginning logmile (at

the western or southern end) with a value of 0.000 and accumulate to the end of the segment’s ending logmile. When a route overlaps (is concurrent with) another route for a distance, the measures for both routes are made along the same piece of roadway. After the overlap ends, both routes continue their respective logmile measures. See Figure 2-2 below for an example.

Figure 2-2: Logmiles for Route Overlap Example



Split Routes

There is a “hierarchy of precedence” to determine which overlapping route is considered to be the primary route. Starting with Interstate Routes as the highest in order of precedence, the order is:

Interstate Routes U.S. Routes State Routes County Routes Township Routes Municipal Routes

A split route is defined as one that is coincident with a State, County, Township, or Municipal boundary for a measurable distance. The associated segment “belongs” to both jurisdictions and is represented as such in ODOT’s RIS. Figures 2-3 and 2-4 illustrate this situation. In the first figure, a Township route follows the Athens-Washington County line for a distance (purple segment). That segment splits and “belongs” to both Counties, and is given appropriate coding in RIS.

Figure 2-3: Route Split by County Example



The second example shows Washington County Route 16 following the Marietta municipal boundary for a portion of its length (purple segment). Although the segment is located entirely within Washington County, because it follows the boundary for the City of Marietta, one side is coded as municipal and the other as rural in the RIS database.

Figure 2-4: Route Split by Municipality Example



Routes that Leave/ Re-enter

Routes that “leave” and “re-enter” occur where there is a physical gap between two segments that have the same route number but are not physically connected. In Figure 2-5, Duncan Road SW exists in two unconnected sections, with a section of limited access U.S. Route 22 preventing their connection. The logmile labeled as 2.072 in two places denotes the leave and re-enter points and measures.

Figure 2-0-5: Route Split by Municipality Example

Figure 2-5: Leave-Re-Enter Example #1



The second example (Figure 2-6) shows another physically disconnected road (Fay Avenue, in light blue). It would theoretically be possible for the Fay Avenue route to overlap two other roads to join the two segments (via State Route 26, shown in green, and Alderman Street, shown in yellow), but ODOT business rules state that no more than one other route can be used to overlap (link) the end of one segment to the beginning of the next segment. In this case, two routes would have to be followed to get to the next segment of Fay Avenue.

Figure 2-6: Leave-Re-Enter Example #2



Data Events and Attributes

Cardinality

Inventory Direction

All roadways are (and should be) inventoried from west to east and south to north (Figure 2-7). If the logmile values increase from west to east, the Compass Direction is East; if the logmile values increase south to north, the direction is North. The four main directions (N, S, E, W) are the Attributes used for this Feature.

An Event is considered a general grouping of physical attributes of a roadway, identified by a unique name; Events have Attributes, which are the codes or values associated with that event. As an example, an Event might be Functional Class; the associated Attributes might include Rural Interstate, Urban Principal Arterial, etc. Depending upon the situation, each Attribute could be represented by a numeric value, a numeric code, or a character code. These Attribute codes are listed for each RIS Event in Chapter 3.

Figure 2-7: Cardinal Inventory Directions



Event Types

Inventory Direction

There are two types of Events – linear and point. Linear Events describe Attributes that are found for a defined, measured distance along a roadway segment, such as number of lanes or pavement type. Point Events occur only at a discrete location along the roadway, like a vehicle crash or jurisdictional boundary. Figure 2-8 shows examples of Linear and Point Events.

Figure 2-8: Linear and Point Events Examples



Attribute Types

Example Attribute Characteristics

Attributes are categorized into the following types:

• Length Attributes. These attributes are associated with a piece of a segment. Examples from the LRS Events table include SEGMENT_LENGTH_NBR and FUNCTION_CLASS_CD.

• Point Attributes. These attributes are associated with a point on a segment. The attribute may be a measurement such as CTL_BEGIN, which indicates the begin logmile measure of a route. Non-measure point attributes include X_RT_STREET_NME (cross route street name) and HOUSE_NBR (house number).

• Physical Attributes. These attributes may be length or point features that describe physical characteristics of the roadway. Examples include STRUCTURE_TYPE_CD (type of structure, including bridges, tunnels, causeways) and SURFACE_TYPE_LEFT (type of surface of left side of roadway).

• Administrative Attributes. These attributes describe non-physical characteristics of a roadway. Examples include COUNTY (county to which the roadway segment belongs) and MUNICIPAL_CD (municipality to which the roadway segment belongs or crosses).

• Automatically Generated Attributes. These attributes are normally not recorded by field data collector personnel, but are automatically generated and populated by ODOT’s computerized systems. Attributes may include automatic numeric sequencing like SEQUENCE_NUM and automatic date stamping attributes such as PERP_YEAR.

Attributes usually contain individual data codes that describe their associated Events. As an example, the following are Attributes of roadway facility type as represented by FACILITY_TYPE_CD:



Code Description

1 One-Way Roadway - Roadway that operates with traffic moving in a single direction during non-peak period hours.

2 Two-Way Roadway - Roadway that operates with traffic moving in both directions during non-peak period hours.

3 Couplet - Non-inventory direction side of a “couplet.” See definitions and guidance for “couplets” below.

4 Ramp - Non-mainline junction or connector facility contained within a grade-separated interchange.

5 Non Mainline - All non-mainline facilities excluding ramps.

6 Non Inventory Direction - Individual road/roads of a multi-road facility that is/are not used for determining the primary length for the facility.

7 Planned/Unbuilt - Planned roadway that has yet to be constructed.


Documents

ROADWAY INFORMATION MANUAL Chapter 2 · ROADWAY INFORMATION MANUAL Chapter 2 – Roadway Data Overview (January 2013) Data Events and Attributes Cardinality Inventory Direction All