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Planning Guidance for the Installation and Use of Technology Devices for Transportation Operations and Maintenance

ENTERPRISE Transportation Pooled Fund Study

DSDS Guideline 2 - Posted Speed Adherence

Purpose: To promote speed limit adherence in locations prone to vehicles exceeding the posted speed limit.

Engineering judgment should be used to assess potential implications that may result from installation of DSDS.  This planning guideline does not mandate the use of DSDS.

1. The 85th percentile speed (as determined by a speed study) exceeds the posted speed limit by at least 10 mph, or by at least 5 mph in a school zone. (3) (1)

AND

2. The area is within 500 yards of a major pedestrian generator (e.g. school, park, library, senior center, office building). (4)

OR

The area is primarily a residential area or a heavily traveled pedestrian area. (4)

AND

3. The posted speed limit is 35 mph or less. (3)

AND

4. There are no other Dynamic Speed Display Signs along the route within a 5 mile in either direction of the proposed sign (excluding DSDS within school zones). (2)

Note: Signs tend to be most effective where there are two lanes or less in one direction of travel.

References:

(1) City of St. Paul Minnesota, Department of Public Works, Traffic Engineering. Dynamic Speed Display Signs . 2004.

(2) Mn/DOT. Dynamic Speed Display Sign Memo. http://dot.state.mn.us/trafficeng/committees/minutes/jul/Attachment%202.pdf.

(3) THE STATE OF VERMONT, Agency of Transportation. Guidelines for the Use of Radar Speed Feedback Signs on. 2009. website: http://www.aot.state.vt.us/documents/3014_Guidelines_on_the_Use_of_Radar_Speed_Feedback_Signs.pdf.

(4) City of Bellevue (Washington), Transportation Department. Stationary Radar Sign Program 2009 Report. 2009.