Comments on: Solving Dilemma Zones

By: MALLEN

MALLEN — Mon, 01 Jun 2009 10:20:51 +0000

A dilemma Zone can be prevented by simply increasing the yellow light time, as usual timings are around 3 seconds, but if this time is increased to 4 seconds it would allow extra time for those who are in the orginal dilemma zone, to pass safely through the intersection.

This option would also create a negative dilemma zone calculation, which imply’s no dilemma zone is present, an overlap of the to situations…. All Positive.

By: Jeff McMullen

Jeff McMullen — Fri, 13 Mar 2009 16:00:17 +0000

Just for the record. The dilemma zone is influence by more than the Yellow or Red time. It is mainly the result of detector placement,the minimum gap timing, vehicle speed and intersection congestion. Actually, Red timing has nothing to do with the dilemma zone. If a driver has made the decision to run the red, he is already past the dilemma zone.

The statement above is born not out of pure research or studies but more than 20 years of field experience.

By: Peter Koonce

Peter Koonce — Wed, 07 Jan 2009 04:11:22 +0000

There is an upcoming study that will be conducted by the National Cooperative Highway Research Program on the issue of setting Yellow and All Red Times. I agree that if drivers knew they may abuse the system. A study cited in the Signal Timing Manual (www.signaltiming.com) by Souleyrette, R. R., O’Brien, M. M., McDonald, T., Preston, H., and Storm, R., “Effectiveness of All-Red Clearance Interval on Intersection Crashes”, Center for Transportation Research and Education, Iowa State University, Minnesota Department of Transportation, MN/RC-2004-26, http://www.lrrb.org/PDF/200426.pdf, May 2004, states that lengthening the time of a red indication has no long term improvement on safety because of drivers learning the system.

By: Mark Hunter

Mark Hunter — Tue, 07 Oct 2008 19:03:55 +0000

The only solution may be a double red light for two or three seconds. Of course, as you say, if people know this, then some may take advantage.