User:Hawkeygoal/IL Pages/IL Dirt Roads (2016 06) History


The goal of this page update is to clarify handling of the dirt road type in Illinois by revising the Special roads section of the Illinois wiki.

This information is under consideration for the Illinois state wiki.
It should not be considered official guidance.

The recent correction of the "dirt" road type to "off-road / not maintained," we are advancing this modification to the Illinois guidance on dirt and gravel roads within the state. This guidance is intended to codify what falls into the "not maintained" category while providing for future inclusion of the, as yet unimplemented, "unpaved" checkbox.


Non-Drivable Roads

The  |   |   |   |   | Walking Trails |   |   |   |   |  and  |  |  |  |  | Pedestrian Boardwalks |  |  |  |  |  road types are not added to the map in Illinois. In general, these road types do not add to the routing function of the application.

Special exceptions may be made with the approval by State Managers. For example, a  |  |  |  |  | Boardwalk |  |  |  |  |  may be used to support house numbers in situations where they are not assigned to drivable road types. This use must be approved by a State Manager (refer to Area Managers table).

Please consult with a State Manager before adding or removing these road types.

Unpaved and Unmaintained Roads

Illinois follows this specific guidance on the use of  Off-road / Not maintained   road types and unpaved roads in the state. This supplements the guidance for road types.

Unpaved roads may or may not be classified on IDOT Functional Classification maps. Maintained, but unpaved, roads should have the unpaved attribute checked. Unpaved driveways should be mapped using the Private Road type, regardless of their condition. Similarly, alleys and parking lot roads should use the appropriate road type. Unpaved roads classified in one of the arterial classes will be mapped as specified in road types guidance. Collector, local and unclassified roads will be mapped as shown in the table below.

Highway System & Road Surface
Gravel Street[b]
examples CH-14 Main St Side St Farm Dr Farm Ln
Major Collector  PS   PS   PS   N/M   N/M 
Minor Collector  PS   PS   PS   N/M   N/M 
Local  PS   Street   Street   N/M   N/M 
Unclassified  PS   Street   N/M   N/M   N/M 

^a A road in a county highway system is always mapped as a primary street, adding the unpaved attribute if the county highway is gravel rather than a paved surface.
^b A narrow gravel road is defined as one less than 14.5 feet from edge to edge. This is less than the minimum width of two lanes as defined by the Federal Highway Administration (FHWA). Vehicles approaching from opposite directions would likely need to leave the roadway to pass.
^c Gravel surfaces on maintained roads should be mapped with the unpaved attribute checked.

 PS   Primary Street 
 Street   Street 
 N/M   Off-road / Not maintained 

To determine if a road falls into the "narrow" category, measure the distance from edge to edge using by creating a temporary, un-saved, segment (using zoom level 9). Create the segment perpendicular to the roadway with end-points at the road edge at each side. The edge being a solid line of grass or other material not part of the road surface. Use the WME Meausurement Tool in WME Toolbox, or the WME True Segment Length script, to measure the length of the segment without saving the temporary segment.


This proposal is under discussion on the forums, at the following link: