Speed Management
Speed management is a holistic approach to influencing driver speeds. Speed management should be utilized when there is a disconnect between vehicle speeds and the roadway context. Some examples of these situations include locations where:
non-motorists are commonly present,
the adjacent land uses are not consistent with roadway character, or
the traveling speed does not match the roadway design.
Research has shown that artificially lowering speed limits does not lead to lower vehicle speeds. Speed limits should be lowered in conjunction with proven speed management measures that lower drivers' comfortable traveling speed.
Speed Management is considered within the framework of the Safe System Approach by reducing speeds to accommodate human-injury tolerances, providing additional time for drivers to stop, and improving visibility. Examples of this are as follows:
If a roadway has frequent pedestrian or bicycle users, then speeds should be managed so that an impact is less likely to be fatal. If speeds can’t be reduced, vulnerable roadway users need to be separated from vehicular traffic.
If there is a high likelihood of centerline crossing crashes, then speeds should be managed so that a head-on crash is less likely to be fatal. If speeds can’t be reduced, centerline crossing can be mitigated via various median types.
Roadways with significant roadside hazards should be kept at lower speeds to avoid severe injury.
Providing advance warning of roadway elements that require driver reaction, like intersections or horizontal curves.
Providing better roadway delineation especially at night.
When there is a disconnect between vehicle speeds and roadway design the solution may not always be to slow traffic. Sometimes on key connectors carrying significant traffic the solution may be to design the roadway to better accommodate the speeds in which users want to travel. This could mean separated pedestrian and/or bicycle facilities, wider shoulders, median barrier, consolidated accesses, improved alignment, or other measures.
UDOT Speed Limit Studies
UDOT has developed a speed limit study as part of the UDOT traffic studies process. Historical speed study methodology suggests that a speed limit be raised when the 85th percentile speeds are more than 5 mph above the posted speed. This can result in speeds constantly creeping up as drivers increase speed and posted speed limits are increased to match. Instead of defaulting to raising the speed limit, the new speed limit studies suggest an appropriate speed based on the context of the roadway and identify proven measures to encourage drivers to maintain that speed.
Speed limit studies are performed through the UDOT traffic studies process in the same manner as traditional speed studies, signal warrants, left-turn studies, and other traffic study types. Requests are generally initiated at the regional or community level, and then submitted through Workflow Manager by UDOT Region traffic engineers.
Speed Management Info Sheets
UDOT has developed Speed Management Info Sheets as a guide to implementing speed management techniques on UDOT roadways. This guide focuses specifically on measures to slow traffic. Design improvements to accommodate higher speeds could be an outcome of a speed management study, but specific recommendations would not be provided.