John Black, Senior Traffic Engineer
Post Number: 3
|Posted on Tuesday, September 26, 2006 - 09:01 am: |
Some agencies do flash the main street signals yellow late at night at minor intersections. This practice is allowed in the MUTCD (Manual of Uniform Traffic Control Devices). The use of night flash is most common for systems without vehicle detection (what we refer to as fixed-time or pre-timed systems).
Some agencies have found a higher accident experience when night flash is used due to the greater incidence of DUI drivers late at night. We have considered implementing night flash as a trial here in Frisco, but see little benefit in reducing delay on the side street. This is because our vehicle detection should allow the traffic signal to transfer the right-of-way within 15-20 seconds if there are no opposing calls from vehicles extending the greeen on the major street. A sober driver stopped at flashing red can take 10-15 seconds to visually determine that no traffic is present on the major street before moving into the intersection. A DUI driver will require longer to make a decision at a flashing red signal and sometimes it is the wrong decision.