Multi-way stop

[Tony753]

Currently, there is a two-way stop at an intersection. This intersection meets the MUTCD warrant for a multi-way stop using the number of accidents (intersection related) in a twelve-month period. The multi-way stop will reduce the number of turning and angle accidents and will also slow down the prevailing speed (which has a 70% violation rate). But I am concerned that there will be more rear-ends. What do you think?

Thanks

 

[ACtrafficengr]

Don't bet on stop signs to discourage speeding. You may well find that mid-block speeds increase as frustrated drivers try to make up lost time.

I wouldn't be surprised if rear-ends did go up, but then again, they are often lower on the KABCO scale than right-angle crashes. Will it be better, worse, or a wash? Hard to say.

Is this a high-speed road? (going by 85th% speed, not speed limit, which sounds like it may well be unrealisticly low). if so, I'd look for other solutions.

Is there a sight distance problem for traffic on the side road? Can it be improved by clearing brush or cutting back hillsides? Often that will improve things as much or more than all-way stop control, without the increased delays for mainroad traffic, and the associated noise and air pollution.

Good luck, and keep us posted.


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"Come to think of it, there are already a million monkeys typing on a million typewriters, and the Usenet is NOTHING like Shakespeare.

- Blair Houghton

 

[Tony753]

The 85% speed is 53 mph and the posted is 45 mph. It is 45 because of the residential neighborhoods. It's true that the stop sign might not help, but it seems like a reasonable temporary solution. The sight distance is not a problem. The problem is the reduction in the speed limit from 55 to 45. People don't pay attention to the signs and the high speeds cause a lot of the accidents. Ultimately a center turn lane is desired, if the funding goes through. Anyways thanks for the advice.

 

[ACtrafficengr]

53 mph approach speed? Most drivers won't expect stop control on such a road. ifyou use all-way stop, consider using oversized stop signs, left-side stop signs, etc, to get their attention.

And keep an eye on those rear-end crashes.

I assume you've done a signal analysis and it doesn't meet warrants?

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"Come to think of it, there are already a million monkeys typing on a million typewriters, and the Usenet is NOTHING like Shakespeare.

- Blair Houghton

 

[movva]

Hi Guys,

I am trying to analyze an intersection with 3-stop signs and free flow on one direction. Can anyone let me know how to evaluate Intersection LOS for this type of intersection?

 

[ACtrafficengr]

I know of no methodology to predict the LOS. You should probably go out and do a delay study.

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"Come to think of it, there are already a million monkeys typing on a million typewriters, and the Usenet is NOTHING like Shakespeare.

- Blair Houghton

 

[francesca]

The only Level of Service categories I've come across have been based on delay.

In the UK, I used PICADY to analyze stop-controled intersections, but there was no accident analysis bolted on, nor any need to input speed. (i.e. PICADY only calculates delay and LOS, based on geometry and traffic and turning volumes.)

Having worked in the UK, I'd recommend a roundabout for this situation if your traffic flows are more-or-less directionally balanced (roundabouts don't work where the highest traffic volumes come from adjacent legs). This could prevent the rear-ending problems you're worried about because under low flow conditions, vehicles usually do not stop at roundabouts. ARCADY, a sibling of PICADY, analyzes roundabouts based on geometry and turning movement data and predicts delay and LOS.

The Australian package, SIDRA, also analyzes roundabouts.

 

[ACtrafficengr]

"The only Level of Service categories I've come across have been based on delay."

Francesca - perhaps I wasn't clear? I meant to say that the US Highway Capacity manual won't predict delay at a 3 leg, two stop sign intersection, but you could measure it in the field. The ITE Traffic Manual delay study method could be used, for example.

Perhaps the more advanced traffic simulation models could do it. I haven't had much opportunity to play with them.

I agree that a roundabout would be worth investigating.

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"Come to think of it, there are already a million monkeys typing on a million typewriters, and the Usenet is NOTHING like Shakespeare.

- Blair Houghton