February 24th, 2011

SIGNALS WHERE WARRANTED

Optimize Mobility, by Catherine Higgins.

“Warrants were issued after an investigation” is a phrase you may hear on CSI or at UDOT.

Bus going through green light in Sandy

Safety concerns, vehicular traffic volume, pedestrian traffic volume and roadway features are few things engineers evaluate carefully during the signal warranting process.

UDOT follows the criteria outlined in the Manual on Uniform Traffic Control Devices –MUTCD — that lists eight aspects of a roadway that need to be studied and individually warranted before the decision to install a traffic signal is made. Here’s the list straight from the source:

  1. Eight-Hour Vehicular Volume
  2. Four-Hour Vehicular Volume,  Peak Hour
  3. Pedestrian Volume
  4. School Crossing
  5. Coordinated Signal System
  6. Crash Experience
  7. Roadway Network
  8. Intersection Near a Grade Crossing

Traffic engineers conduct studies according to the requirements outlined in the MUTCD, crunch the data and make a decision.

R-E-S-P-E-C-T

It’s important to follow the MUTCD to ensure that a signal is really needed at the location. ” You want that device to get the respect of road users, ” says Mark Taylor, UDOT Signal Systems Engineer. “Otherwise, you get safety problems,” like excessive rear-end crashes, if drivers disobey the signal.

But the engineers also use good judgement when placing signals, too. “Just because it meets the requirements, we don’t need to put it there,” says Taylor.  Another approach, such as signs or flashing warning lights may provide the needed improvement.

To find out more about the warranting process, and how to request a signal in your area, see this traffic signals brochure produced by the UDOT Traffic and Safety Division.

A related post explains flashing yellow arrows: UDOT GETS FLASHY

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  1. Tweets that mention SIGNALS WHERE WARRANTED ­ UDOT Transportation Blog -- Topsy.com (,February 25, 2011)

    [...] This post was mentioned on Twitter by Utah DOT, Dynamite Utah. Dynamite Utah said: RT @UtahDOT: Curious about how UDOT determines if a signal should be placed at an intersection? Check out our blog, http://bit.ly/fXRsvn [...]

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