Ada County Highway District

ACHD's Road Wizard Sunday, February 17, 2019 ACHD's Road Wizard

Abandoned toilet on the road at Malad and Janeen streets; "drag racing" at Victory approaching Maple Grove Road; should signals in downtown Eagle be coordinated like signals in downtown Boise?

The Road Wizard Replies

Dear Road Wizard: There is an abandoned toilet on the road close to the intersection of Malad and Janeen streets. It has been there for over a month. I think it was left when the lot on that corner was cleared (an old trailer house was there). Who is responsible for picking this up and disposing? We need it gone!


Road Wizard:

There is no toilet-paper trail leading to who left the bowl behind. The job of collecting the toilet does not fall under the job duties of the Ada County Highway District, but the maintenance department went out and collected it. At least it gave crews a good excuse for having a little potty talk in the break room.

Dear Road Wizard: I see a problem at Victory approaching Maple Grove Road. Victory has two westbound lanes, but only has a single lane west of Maple Grove. The left-hand lane is "supposedly" considered the lane for through traffic, but unlike the previous example, cars in the righthand lane are not forced to turn right, but instead may continue west and merge with traffic beyond the intersection. People will take "cuts" and I witness "drag races" every day. This intersection is in a school zone. What would it take to force a right turn for traffic in the right lane?


Road Wizard:

For westbound Victory at Maple Grove, a forced right turn would cause a significant increase in evening peak-hour delay because there is a strong demand for westbound traffic continuing through the intersection on Victory, and a fairly low demand for right-turning traffic onto Maple Grove. ACHD confirmed this with a recent study of the intersection.

A few years ago, ACHD extended the merge area west of the intersection, and there aren’t any reported crashes in the past five years directly related to the merging. At this point, no lane assignment changes are planned.

Dear Road Wizard: What gives with traffic in downtown Eagle? Southbound Eagle Road traffic gets stopped at State Street much more frequently despite minimal volume on State. Then as soon as you get through, you get stopped at Plaza Drive for two cars. Then as Plaza turns green for Eagle Road traffic, Idaho 44 turns red. Maddening. Why can't we coordinate traffic like in downtown Boise, where one light turns green and they all turn green?


Road Wizard:

Boise's core is a grid network and traffic signals are coordinated in "fixed time." Many of Boise's downtown streets are one-way, which makes it easier to coordinate signals to provide "one green, all green" service.

Downtown Eagle signals are farther apart and don't have the traffic patterns to support fixed time operation. They work best by mixing traffic detection and signal coordination. For example, whether there is one car or 30 at a signal in downtown Boise, the green light lasts around 30 seconds. In Downtown Eagle, if there is only one car, the green time may only be five seconds.

The flexibility of Eagle's signals provides the most possible green time for Eagle Road. However, the next light may be red if drivers arrive before their turn in the programmed signal cycle.

The alternative is to have a rigid green light time, regardless of the number of drivers on the road. It would improve the appearance of traffic "flow," but Eagle Road would have less green time overall.

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