Intersection Conflict Warning System Human Factors: Final Report

CHAPTER 1. OBJECTIVE

The overall objective of the Intersection Conflict Warning Systems (ICWSs) Human Factors Research project is to provide recommendations regarding the potential standardization of the content and placement of activated conflict warning signs at rural stop-controlled intersections. The project focuses on warning systems for the intersection of rural two-lane stop-controlled minor roads with the following types of roads:

• Two-lane through roads.
• Multilane undivided through roads.
• Multilane divided highways.

The project provides treatment recommendations for the through road and minor (stop-controlled) road.

The purpose of the ICWS is to provide warnings to drivers at or approaching a rural intersection of the presence of potentially conflicting vehicles on the intersecting roadway. The components of the system are a sensor to detect the presence of the potentially conflicting vehicle and a warning sign with beacons that flash when activated by the sensor. The warning signs are typically yellow diamonds, although rectangular yellow and blank-out signs (i.e., light-emitting-diode-based signs with yellow lettering that are blank when the power is out) are sometimes used.

On the through road, the warning signs are most often placed upstream of the intersection at the location where an intersection-ahead warning sign (e.g., W2-1) would normally be located.⁽¹⁾ Rectangular overhead signs with beacons at the intersection itself have also been used.

On the minor road, the warning signs may be located across the roadway from the stop line or along the side of the major road with the face of the sign facing the driver when viewed from the stop line. The latter implementation is intended to warn drivers who are already looking in the direction of the potential conflict; the former option is intended to alert drivers who may not have looked for or seen potential conflicts.