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

ENTERPRISE Transportation Pooled Fund Study

DMS Guideline 2 - To Inform Travelers of Traffic Conditions

Purpose: To provide current traffic status information (incidents, congestion, travel time, road work) to drivers so that drivers can choose to divert to avoid the situation, to reduce driver anxiety, and to reduce crashes involving drivers encountering unexpected stopped traffic.

The Manual on Uniform Traffic Control Devices (MUTCD) contains the national standards governing all traffic control devices. DMS (described as Changeable Message Signs in the MUTCD) are one traffic control device covered by the MUTCD (MUTCD 2009 Edition Chapter 2L. Changeable Message Signs. In MUTCD Section 2L:

Section 2L.01 addresses the description of Changeable Message Signs;

Section 2L.02 addresses applications of Changeable Message Signs;

Section 2L.03 addresses legibility and visibility of Changeable Message Signs;

Section 2L.04 addresses design characteristics of Changeable Message Signs;

Section 2L.05 addresses message length and information of Changeable Message Signs:

Section 2L.06 addresses installation of permanent Changeable Message Signs.

The planning guidelines are intended to be an additional tool to assist agencies in the decision process of selecting when and where to deploy DMS technologies, based up the experiences of agencies that have previously deployed DMS.

Engineering judgment should be used to asses potential implications that may result from installation of DMS. This planning guidance does not mandate the use of DMS.

The guidelines do not distinguish between types of DMS (portable, overhead, roadside).  Rather the intent of the guidelines are to contribute to the understanding of the need for some type of DMS.  Detailed design would contribute to the selection of the specific DMS type.

 

1. If the target area is monitored by CCTV cameras, traffic detectors, or another method of monitoring the conditions, or are travel times for the downstream stretch of road.

AND

2. Events occurring in the area unexpectedly impact or impede traffic (e.g. close a lane, encounter slow traffic in one or more lanes, or events on the shoulder) an average of at least two times per month.

AND

3a. If there are acceptable alternate routes with capacity to accept vehicles that may deviate based upon the information.

OR

3b. If the location is a stretch of road where no alternate route are possible and travelers would benefit from information describing the cause and/or extent of delays in order to relieve driver anxiety or confusion.

OR

3c. If there are horizontal or vertical curves that create safety issues when traffic is stopped unexpectedly.

AND

4. The route being considered for the DMS has on average

• At least 2 hours of peak period travel where traffic flow exceeds 1,100 veh/hour/lane; or
• Experiences conditions considered Level of Service C; or
• Experiences average annual daily traffic (AADT) of 16,800 for a 2 lane road; 33,600 for a 4 lane road; 50,400 for a 6 lane road; 67,200 for an 8 lane road.

Partial Guideline Criteria:
If #2 above is met, the guideline is considered ‘Partially Met’. If one or more additional purposes are partially met at this location for this device, the device should be considered.