Sight distance is important for a treatment that supports two-way vehicular traffic on a single lane. Sufficient sight distance must be available for drivers to be able to respond to approaching vehicles and either come to a full stop or maneuver into the edge lane to pass.
Current American guidance specifies Passing Sight Distance as the sight distance needed for an ELR. This is incorrect.
The peer-reviewed article linked below explains why Passing Sight Distance is wrong, discusses other sight distances that are used for similar facilities, and crafts two ELR-specific sight distance models from established research that are conservative enough for practical use until field research is able to refine these models.
Current American guidance specifies Passing Sight Distance as the sight distance needed for an ELR. This is incorrect.
The peer-reviewed article linked below explains why Passing Sight Distance is wrong, discusses other sight distances that are used for similar facilities, and crafts two ELR-specific sight distance models from established research that are conservative enough for practical use until field research is able to refine these models.
| sight_distance_for_edge_lane_roads_august_2021_michael_williams__4_.pdf |
Photo courtesy of Scott Robinson at City of Bloomington, IN.