Sequential Dynamic Chevron Warning System

Image Source: Iowa State University Center for Transportation Research and Education

DEFINITION AND DESCRIPTION

A sequential dynamic curve warning system (SDCWS) consists of a series of solar-powered LED chevron signs installed along a curve. Signs flash in sequence when a radar or another detection device detects approaching vehicles, alerting drivers to reduce their speeds as they navigate the curve. They can replace existing chevrons and are good in low-visibility conditions. 

Implementation Categories

CONSIDERATIONS

• Requires a radar detection system.  Some applications include a constant flash.
• Requires solar power.
• May need to set speed thresholds.
• Consider friction curve data and potential collisions with signs.
• Lowers speeds and reduces crashes (Smadi et. al., 2015).

APPLICATION

• May be considered on high-speed facilities along sharp curves with poor safety performance.

example

Pennsylvania DOT (PennDOT) piloted SDCWS in several locations and is developing a statewide approval process for sign installations. Its specifications have been updated to include flash rates, five acceptable colors, dimming, optional traffic detection, and flashing sequence. Requirements are documented in the agency’s Qualified Products List. 

Complimentary Countermeasures

• Enhanced Signing
• Curve Widening
• Horizontal Signing Pavement Markings