Ada County Highway District

ACHD's Road Wizard Sunday, July 7, 2019 ACHD's Road Wizard

Can you make a left turn on a red left arrow; signal timing with Flashing Yellow Arrows; a weed-infested mess on Knox Street

The Road Wizard Replies

Dear Road Wizard: : I have almost got to the point that I recognize and react to the newly enacted flashing yellow left turn arrow. But today I saw a car make a left turn on a red left arrow while I was stopped at Lake Hazel and Maple Grove. She pulled off the turn slick enough, but left me wondering if this is something that is allowed now or is it just a driver with entitlement problems?

Very Curious

Road Wizard:

Hello Very Curious! I consulted the wizard texts and it turns out that proceeding on a red arrow signal is never legal in the state of Idaho. This applies to both left and right turn red arrow signals, and the same is true for red ball signals with "No Turn on Red" signs.

Dear Road Wizard: Heading south on N. Locust Grove at E. Franklin Road, there were no cars in the two left turn lanes. The light to go straight turned green, and then myself and another car pulled into the left turn lanes. However, the left turn light stayed red for the duration, and we did not get to go until the traffic on Franklin went through that cycle. Why don't the left turn arrows turn green at the same time as the straight-ahead lights do, so the turn can be made? Or blinking yellow? I've seen this at other intersections as well.

Dave H.

Road Wizard:

First, Flashing Yellow Arrows are not installed on intersections where two left turn lanes are present. This is because the risk of potential conflicts is too great and the challenge of sight distance.

What you have described is the normal operation of the signal. It's all about timing. Detection devices (cameras or radar units) are used to see whether there are vehicles in the turn lanes, so when the signal sequence began and no one was present in the left turn lanes, those lanes did not get a green arrow, and the opposite direction's traffic then got a green light. Some intersections have "recall" abilities, meaning they could serve the left turn again if the opposite direction is clear and there's enough time left in the signal cycle. This typically only occurs when traffic is light, as the signal is taking all directions into account, not just one vehicle.

Dear Road Wizard: The west side of S. Knox Street, in Star, used to be a beautiful tree-lined street, although somewhat overgrown. Then, Idaho Power and Ada County decided to remove them all rather than trim. The county tried a couple of foliage things in their place, but nothing lasted. Now it's an ugly weed-infested mess. Hoping something can be done about it.


Road Wizard:

My crystal ball took me back to the radical 90s when ACHD did maintain this area. Idaho Power took down the trees for power line installation and it fell to the wayside of different agencies. Rest assured, it is on ACHD's radar now and crews will come out to clean the area up and deal with the weeds.

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