Ada County Highway District

ACHD's Road Wizard Sunday, October 27, 2019 ACHD's Road Wizard

Stop before proceeding on green arrow; speed limit reduction on from Federal Way to Willoway Drive; need for a "Road Curves" sign

The Road Wizard Replies

Dear Road Wizard: On State Street, in the dedicated lane to turn right onto Veterans Memorial Parkway, with a steady red light and a green right arrow, am I required to stop before proceeding in the direction of the green arrow? If I'm not required to stop, why is there a steady red light in a dedicated right turn only lane?


Road Wizard:

Green arrows, either right or left, mean that the driver in the designated right or left turn lane has the right of way. In this case, the red circular indication is intended for the corresponding through movement at the intersection, which does not have the right of way when displayed with the green right arrow. Established signal standards require that, if there is a green right arrow displayed, the red "ball" for the same direction through movement also be displayed.

On a side note, green right turn arrows are never displayed in conjunction with the conflicting pedestrian walk indication. In this case, that means the eastbound right turn green arrow doesn't appear when the "walk" sign is displayed for pedestrians crossing the south leg of the intersection.

Dear Road Wizard: Our street speed limit is 20 MPH and there is no way to safely slow to that limit from Federal Way to Willoway Drive. Many of my neighbors have written in to ACHD hoping to get a speed limit reduction to help with drag racing, tailgating, and for the safety of the animals and kids in our neighborhood. I'd really appreciate if you could look into this.


Road Wizard:

ACHD performed a speed study in that area in July of this year and found that the average speed traveled was 42 MPH. It is important to note that aggressive driving is different from speeding, and rarely does a change in the speed limit curtail aggressive behavior such as tailgating. Lowering the speed limit can actually cause more tailgating.

Drag racing is unlawful behavior regardless of posted speed limits, and generally drivers who engage in such behavior are the least likely to be influenced by a speed limit change. It would be pertinent to share your video (which did not come through to me) with the Boise Police Department, as this may be an enforcement issue.

Dear Road Wizard: So now that the new Collister Drive intersection is almost complete and the road signs have been installed, I think you may have missed one. Shouldn't there be a "Road Curves" arrow sign on southbound Collister Drive as you approach the new section?


Road Wizard:

The radius of the curve of southbound Collister Drive approaching State Street is 330. The wizard texts referencing standard urban roadway design states that the minimum design radius for the given speed (in this case 30 MPH) is about 275. This curve radius exceeds the minimum, so curve warning signage is not necessary.

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