August 13


Should We Preempt Traffic Signals in Bad Weather?

By Mike Spack

August 13, 2015

Pedestrians, traffic signals, weather

Bad Weather Signal OperationsJon Freeman posted the following (interesting) idea on the ITE Community Forum that got a lot of traction:  Should we preempt a traffic signal for a pedestrian in bad weather to get them the walk indication sooner than if the signal ran through its normal cycle?

Our industry currently preempts traffic signals for emergency vehicles as well as trains.

There were a lot of comments on the forum, ranging from great idea to impractical.  Whenever a traffic signal is preempted, it throws off signal coordination and can end up adding a lot of delay to the vehicles along the corridor.

The idea is technically feasible, whether we end up giving full preemption or “priority” (which moves the signal cycle faster while keeping the coordination in tact) for pedestrians/bicyclists during bad weather.  Traffic adaptive systems like Rhythm Engineering’s InSync system would make this concept even easier to implement.  And of course the computer running the signal would need to have a “bad weather” input sent to it.

Of all of the responses on the ITE Community Forum, I align with transportation planner/blogger Jeff Riegner’s most (to the point that I didn’t respond to the thread after I read it):

This is a question of how we measure the success of our streets. As with all elements of Complete Streets, and with transportation in general in the 21st century, we as transportation engineers are called upon to consider many factors as we design and operate streets. Streets facilitate mobility for all modes and types of users, of course, so safety and capacity measures continue to be important. But streets also play other roles: as generators of economic vitality, as public open space, and so forth. Each community must make value judgments about which factors are most important to them. An increasing number of communities are prioritizing walking because they see direct economic, public health, and livability benefits. Jon’s idea is an innovative way of making that happen.

A statement of unknown provenance sums it up nicely: “If you plan for cars and traffic, you get cars and traffic. If you plan for people and places, you get people and places.” As transportation professionals I suppose we should have the capacity to serve both kinds of communities. 

I’d like to hear from you. What are your thoughts on whether traffic signal timing should be preempted in bad weather?

Photo Source:  Tim Sackton

{"email":"Email address invalid","url":"Website address invalid","required":"Required field missing"}
Mike Spack

My mission is to help traffic engineers, transportation planners, and other transportation professionals improve our world.

Get these blog posts sent to your email! Sign up below.