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Federal Highway Administration Research and Technology
Coordinating, Developing, and Delivering Highway Transportation Innovations

This report is an archived publication and may contain dated technical, contact, and link information
Publication Number: FHWA-HRT-10-073
Date: November 2010

Roadway Geometry and Inventory Trade Study for IntelliDriveSM Applications Applications


This appendix summarizes stakeholder feedback from the Web meetings on roadway geometry and inventory information needs.


The following comments were received from stakeholders regarding the roadway geometry data elements:

  • Stakeholders generally agreed that information on basic roadway geometry and curvature are critical data elements in the short term.
  • Additional data elements include sight distance for passing and stopping and slope of the road for braking purposes.
  • One stakeholder observed that the data elements related to vertical alignment appeared to focus on curves only. Many urban areas have elevated roadways or multilevel bridges, and it would be necessary to distinguish between vehicles traveling on the elevated portion of the roadway and cars traveling underneath the road, where the GPS signal could potentially be blocked. It is important to capture this third dimension (i.e., the z measurement). Additional research is needed in this area.


The following comments were received from stakeholders regarding the roadway inventory data elements:

  • One stakeholder suggested that speed zone data should be provided at the lane level. For example, Canada has many locations where there might be variable lane speeds across a single segment of road.
  • Additional data elements include locations of the edge of travel lanes; locations of bicycle paths/lanes; guardrail information; overpass height restrictions; locations of runaway truck lanes, particularly in mountainous areas; restricted lane use for trucks and transit vehicles on freeways; and pavement condition data and pavement coefficient of friction, particularly during inclement weather conditions.
  • High-occupancy/toll (HOT) is listed as a lane use restriction type, but additional information is needed on whether a lane is tolled and the type of toll in place (e.g., variable, fixed, based on time of day, etc.).
  • For HOV lanes, the presence of lane barriers (e.g., continuous flow HOV lane or barrier separated) should be included as part of the lane geometry.
  • Data elements needed for transit applications should also be considered. Transit-related data include transit stop locations, hard shoulder running for buses, and type of transit stop (e.g., in-lane, pulloff lane, contraflow pullout stops for buses). Transit stop type is important because it impacts how a transit vehicle merges into traffic. Other transit data include queue jump and transit signal priority (TSP). These data are highly dynamic with respect to whether TSP is engaged, route schedule considerations, etc.
  • Stakeholders suggested that obtaining speed zone data would not be easy, as there is no one-stop data source that includes posted speed information. The same applies for reduced speeds in work zones, particularly when the work zone is in place for a year or more.


The following comments were received from stakeholders regarding intersection-related data elements:

  • Stakeholders generally agreed that the location of stop-controlled intersections is a high-priority data element for intersections.
  • Additional detail is needed to identify the location of the intersection (i.e., locating each of the four corners of the intersection), as well as the location of the stop bar on the approach.
  • Stakeholders suggested that the location of the start of a left- or right-turn lane would be more relevant than the length of the turn lane. This would provide information on the transition from regular travel lanes to an intersection location.
  • In order to implement the intersection-related applications, one stakeholder suggested that a linkage between the signal control status and lane configuration would be needed. It is important to provide mapping between lanes and the signal phase they are matched with. Information on pedestrian protection controls also would be needed.
  • One stakeholder suggested that vehicle path and centerline data would be more efficient and relevant for collision applications at intersections, rather than the data elements that are listed. This would involve drawing vectors through the intersection to represent potential vehicle paths. If vehicle paths are predefined, it is possible to then provide information regarding warnings or near collisions. Detailed intersection configuration data may be needed to calculate vehicle paths, however.
  • One stakeholder suggested that data elements for intersection-related applications should capture normal operations as opposed to unexpected conditions.


The following comments were received from stakeholders regarding other geospatial data elements:

  • Stakeholders suggested that the start and end location of bridges would be more pertinent than bridge length.
  • Additional data elements for commercial vehicle applications include the location of truck parking facilities; facility capacity and availability of truck parking; right-of-way information for wireless inspection applications; posted and actual vertical clearance of overpasses; weight restrictions for bridges; and locations of commercial vehicle restricted zones in suburban/urban areas.
  • Information related to border crossings would also be useful for commercial vehicle applications. Data elements could include border wait times, whether particular lanes are fast/normal lanes, inspection regimes, and other relevant factors.
  • Information on the movement of dangerous goods and hazardous materials through an area is also important, particularly for disseminating information to first responders in case of an emergency.
  • Railroad crossing data elements are applicable for all IntelliDrive applications, not just those related to commercial vehicles. One stakeholder suggested that railroad crossing control status also would be an important data element. One stakeholder pointed out that at some locations, railroad crossing status may not be available, particularly in rural areas where there may be unregulated crossings that have no control type.
  • Stakeholders generally agreed that knowledge of locations where real-time traffic information is available would be useful, particularly to commercial freight operators for route diversion based on congestion. The locations of road condition coverage also would be useful.
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