Talk:902.5 Traffic Control Signal Features (MUTCD Chapter 4D)

From Engineering Policy Guide
Jump to: navigation, search

This is in reference to retroreflective backplates for signalized intersection. I noticed in EPG 902.5.17 that we have two different breakouts speaking about the retroreflective backplates. This is fine but we spell out two different speeds (mph) that the retroreflective backplates should be installed on. 55mph and 45mph - according to MUTCD, they mention that the retroreflective backplates should be installed on 45mph travelways. Please let me know what you think? Thank you for your time and consideration.

Keith L. Smith: Thanks for the question. Traffic Division's response follows:


Below are portions of EPG 902.5.17 that reference the use of reflectorized backplates and speed limits:

For approaches with operating speeds equal to or greater than 55 miles per hour, backplates shall have a retroreflective border.
Retroreflective backplate borders should be installed at signalized intersections where enhanced signal visibility and conspicuity is desired in daytime and/or nighttime conditions. Such signalized intersections include, but are not limited to:
  • signalized intersections with operating speeds greater than 45 mph
  • signalized intersections with busy or confusing backgrounds
  • signalized intersections with automated enforcement
  • isolated signalized intersections
  • signalized intersections that are the first signalized intersection upon entering a city or in an unexpected area.

The MUTCD doesn't specify a speed limit for using retroreflective backplate borders. It states:

Option - A yellow retroreflective strip with a minimum width of 1 inch and a maximum width of 3 inches may be placed along the perimeter of the face of a signal backplate to project a rectangular appearance at night.

When the guidance in EPG 902 was written, the intent for when to use retroreflective backplates was for high-speed rural locations (ie...shall use them when speed limit is 55 mph or higher)....and there is also additional guidance ("should statement") shown above for other instances that are appropriate.

A district should use the guidance in the EPG and engineering judgement when deciding whether a specific intersection is an appropriate location for using retroreflective backplates.