the "political" traffic signal warrant 3

[CaliforniaTraffic]

We currently have a situation where the developer's traffic impact study evaluated an intersection and determined that NO signal warrants will be met in the existing + project condition. Our own annual studies support this finding. But yet in the future when further development occurs the intersection will definitely meet warrants. Because the new subdivision is adjacent to the intersection, the City Council added a condition for them to signalize the intersection. There is definitely concern from our engineers over liability at this intersection. Have others dealt with this "political" signal warrant? Do you let it go? Refuse to approve the plans? Refuse to prepare/sign off on the timing sheet?

 

[CarlB]

One approach is to have the developer install some of the hardware to facilitate future signal installation, when warranted. Or have the developer just pay the "ransom" to be used for the future project.

 

[TerryScan]

This is good example of where something like impact fees make more sense for infrastructure than simple warrants.

Like your scenario - in my area, many developments will contribute the failure of an intersection, but the one who pays for it is the development which is unlucky enough to be the “straw that breaks the camel’s back”.

It seems better all around to have impact fees which go to an escrow which is slated for specific future improvements.

 

[CaliforniaTraffic]

We have impact fees in place. Where warrants are not met on a development, they just pay their fees. The elected officials in this case said not good enough and they wanted the signal in even though warrants are not met. Everything in excess of a developer's fair share fee obligation in our system is reimbursable.

 

[roncity]

Did the politicians specifically reuire a fully operational red/yellow/green traffic signal?
If they said "signalized intersection " ; maybe install the signal and operate it on flash with yellow on the main street until the traffic builds up to warrent full operation...

 

[CaliforniaTraffic]

Thanks roncity for the post. They required the developer to install it but did not get into details in this additional condition of development. Thus if it goes in but warrants are still not met, your suggestion is a good one. It is already a 4-way stop so I would just operate it on red flash. My experience tells me that the community will start calling shortly after that to complain that the signal is not operating yet. Thus I am hoping that other adjacent developments result in warrants being met and this being a non-issue.

 

[teeman]

In some circumstances we have require developers to install the underground infrastructure associated with a signal prior to actual warrants being met. However, traffic projections are such an inexact science that many commercial developments that forecast the meeting of warrants in the future never actually reach the warrant thresholds.

The basic question regarding the political warrant is what governing body has regulatory responsibility for approving the installation of a traffic signal. If that responsibility lies with the city council, then their decision trumps the engineering study/warrant analysis. If the council does not have regulatory authority, they cannot place a condition on the developer that requires another governing body to approve a signal.

If the intersection operates well as a four-way stop, it may not operate "better" under signal control. Signals always increase delay to some movements, and may increase overall intersection delay.

 

[francesca]

I believe that the original poster was not concerned with the cost to the developer of installing the signal, but rather the liability and responsibility as an engineer to the public of designing a signal when it's not warranted and may lead to an increase in accidents.

It's one thing to say that liability for "preventable" accidents transfers to the local authority who demanded the signal, but then it's essential to have a paper trail. This doesn't remove the engineer's obligation to society, however. As the poster suggested, he could refuse to stamp the plans, but is that overkill? Is it a critical enough issue to risk losing the relationship with the local authority or client over? I imagine that it depends on many factors, mostly related to the geometry and traffic conditions of the intersection. An accident analysis is probably called for, either to pursuade the local authority not to put the intersection in, or to assuage fears of liability issues.

roncity's suggestion to operate the intersection with flashing orange and red lights is probably the best solution to the case.

 

[ACtrafficengr]

A recent NCHRP research digest cites a Philadelphia study about removing unwarranted signals:

http://www.trb.org/publications/nchrp/nchrp_rrd_299.pdf,

Page 14.

Using the latest Empirical-Bayes statistical techniques on 199 sites, they show an accident modification factor (AMF) of 0.76 overall (24% reduction in crashes) after the signals were removed, and an AMF of 0.47 (53% reduction) in severe injury crashes.

So this shows that unwarranted signals can cause more crashes than they prevent.

Now, here is a hunk of halite to chew on: "It is important to note that this study was for one-way streets in an urban environment. There are no comparable studies for two-way streets or for intersections in rural environments."

But still, it's food for thought...

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"...students of traffic are beginning to realize the false economy of mechanically controlled traffic, and hand work by trained officers will again prevail."

Wm. Phelps Eno, ca. 1928

 

[teeman]

In some areas the regulatory authority to install traffic signals is the responsibility of a Traffic Engineer. In others it may belong to a city council, a commission or some other governmental body. It is a relationship that relies on the professionalism of the parties involved to act in the public interest.

In providing support services to a regulatory body, the engineer has a responsibility to make a recommendation based on conditions existing at the location, the MUTCD Warrants and his/her engineering judgement. There will be times when what that recommendation should be may not be readily apparent, and others when it is quite clear.

The "political warrant" is usually applied to a location where conditions would not clearly justify the operation of a traffic signal, where the engineer has made his best recommendation, and the body having regulatory authority did not accept that recommendation.

The engineer may disagree with the decision. The engineering report would be a record of that disagreement. The approving authority has the final say.

 

[ACtrafficengr]

If site and traffic conditions allow, would the City Council go for a roundabout? NYSDOT required a developer to replace a signal with a roundabout in Columbia County, NY this past summer.

They were adding a 5th leg to an existing K-shaped intersection, so a signal probably would have worked poorly, anyway.

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"...students of traffic are beginning to realize the false economy of mechanically controlled traffic, and hand work by trained officers will again prevail."

Wm. Phelps Eno, ca. 1928