Ada County Highway District

ACHD's Road Wizard Sunday, November 25, 2018 ACHD's Road Wizard

New Veterans Memorial Parkway/State Street/36th Street intersection goes all red; Ustick and Maple Grove intersection mysteriously loses a flashing yellow left; what's up with the new road west of Discovery Way that goes down from Chinden Boulevard

The Road Wizard Replies

Dear Road Wizard: Twice this week I have encountered flashing red lights at the vaunted new Veterans Memorial Parkway/State Street/36th Street intersection. Eight lanes of traffic, plus left turns, were having to navigate the stop-and-go situation and it was not pretty. Many drivers were poaching their turn and multiple vehicles were proceeding out of proper turn sequence. No officers were on scene to direct traffic and bring order to the chaos; this is unconscionable for such a dangerous situation. Flashing "red/stop and go" works for single lanes on both streets, but not at a multi-lane, complex intersection.


Road Wizard:

Adjusting to the new "ThrU-turn" intersection is complicated enough without red signals in every direction, but the blinking red was a default response to some minor signal operation issues.

The new intersection has left-turning activity from State down the road about one city block east and west of Veterans. Drivers now use U-turns and right turns to complete their left turns. The signals are located differently than traditional intersections, but the activation of the signals was like any other turn-on process.

ACHD tested the signals in house successfully before implementation at the intersection. Unfortunately, testing doesn't always guarantee it will function the same way in the field, which was what caused the issues at Veterans/State/36th.

When signal technology senses that something is amiss, the intersection defaults to "all-red-flash" mode. This is to prevent something truly unconscionable like green lights activating in error and sending drivers into the path of other vehicles.

The issues that popped up weren't things that could be coordinated with a police presence, but they have all been addressed. Drivers need to remember that flashing red signals are to be treated as all-way stops no matter how many approach lanes, or ThrU-turns, are at the intersection.

Dear Road Wizard: I use Ustick Road eastbound every morning. I used to be able to make a left onto Maple Grove using the flashing yellow left. It's now a solid red after the initial green-turn signal. Usually, there is virtually no traffic coming the other way. As I go past, I look in my rearview mirror and I can see that there is a flashing yellow left from westbound Ustick onto southbound Maple Grove. What gives?


Road Wizard:

ACHD's analysis of traffic volumes showed that the eastbound Ustick flashing yellow arrow signal at Maple Grove shouldn't need to be restricted in the morning. However, the signal timing plans show something different. In the morning and evening commutes, flashing yellow arrows are taken out of the rotation, leaving drivers with only the protected green arrow signal option.

ACHD is verifying what is behind the inconsistency. A change back to the flashing yellow in the morning is likely.

Dear Road Wizard: There is a new road (still closed) just west of Discovery Way that goes north and down the hill from Chinden Boulevard. It connects to Colchester Drive, but a one-way sign indicates traffic will only be coming up the hill to Chinden. What is its purpose? Is a connection to Joplin Road possible in the future?


Road Wizard:

This is a private road that will be gated and provide access to a handful of homes, and there won't be direct public access to Joplin. The road is one-way exiting to Chinden right now because access to the road from Chinden requires a right-turn lane that is not yet constructed.

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