Ada County Highway District

ACHD's Road Wizard Sunday, July 8, 2018 ACHD's Road Wizard

A right-turn-only lane on westbound Parkcenter Boulevard at Park Boulevard would increase overall intersection delays; Broadway Avenue off-ramp and under Federal Way in need of cleaning; left turns will not be restricted from Coffey Street onto Chinden Boulevard

The Road Wizard Replies

Dear Road Wizard: Is there any possibility of considering that the right-most lane heading toward Downtown Boise on the west Parkcenter Boulevard bridge be made into a right-turn-only lane? A lot of the signal time is for those turning left from Park Boulevard onto the bridge, allowing considerable time for right-turning traffic. There could even be a green right-turn arrow during that Park green light to speed up traffic flow from the bridge. 

Road Wizard:

Engineers use traffic counts from intersections to create simulated traffic scenarios on computers. This makes it possible to see how any changes to signal timing or lane usage will likely impact traffic flow.

ACHD used this technology to see how a right-turn-only lane on the west Parkcenter bridge/Park/Clearwater Lane intersection would play out during peak travel periods.

There are three through-traffic lanes on westbound Parkcenter at Park. The simulation showed that forcing through-traffic drivers into two lanes in order to create a right-turn-only lane would actually increase overall intersection delays. That's because only a fraction of traffic is turning right. Another reason to stick with the existing layout is that the shared right-turn/through-traffic lane isn't long enough to provide much waiting room for turning traffic.

Dear Road Wizard: I am wondering who is in charge of maintenance for the Broadway Avenue off-ramp and under Federal Way? Weeds, trash, curb dirt! This is not a good introduction to the city and the main corridor to Boise State University!

Road Wizard:

Two agencies share the routine cleanup duties in this area - ACHD and the Idaho Transportation Department. ACHD sweeps the street, ITD handles the weeds and off-road debris. You can expect a visit from both in the next couple of weeks.

Dear Road Wizard: I would like to suggest that the intersection of Coffey Street and Chinden Boulevard in Boise be made a "no left turn" intersection from Coffey. When I was making a left from Chinden onto Coffey, there were cars on both sides of Chinden (on Coffey) trying to make left-hand turns. I occupied the left-turn lane on Chinden traveling west, but there was a car still interested in making the turn from Coffey onto Chinden going east. I couldn't get off Chinden fast enough. I was afraid for my life. I am not a giant fan of traffic restrictions but a "no left turn" sign on both sides of Chinden at Coffey will save lives.


Road Wizard:

For those unfamiliar with this intersection, Chinden is a four-lane road with a shared center turn lane/left-turn lane and Coffey is a side street west of Glenwood. There isn't a traffic signal, but Coffey has stop signs. Drivers on Coffey may want to turn left onto Chinden while drivers on Chinden are waiting to make left turns of their own.

Records show that between 2013 and 2017 there were eight crashes that involved vehicles either turning from Coffey onto Chinden or crossing Chinden. Two resulted in minor injuries. There were also a couple of crashes involving left turns from Chinden onto Coffey and one involving a right turn from Coffey onto Chinden.
But these crashes don't justify restricting left turns from Coffey onto Chinden. Especially when it would require a lot of complaint-worthy out-of-direction travel for residents and businesses.

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