ACHD's Road Wizard Sunday, April 15, 2018

One-way streets can have many benefits. Traffic signal timing tends to be much easier and the green lights can seem like they just keep coming. A case in point is on Myrtle and Front streets in Downtown Boise -- although even those one-way roads can clog up due to traffic overload during rush hours.

But it's generally best to keep one-way roads within the confines or upon approach of a downtown traffic grid. One-way roads are most efficient when a parallel route in the opposite direction is about a city block away. Outside of Downtown Boise, the Meridian Split Corridor is another local example of an effective one-way road pairing because the roads are close together.

One-way roads tend to work poorly in suburban areas where the main arterials are spaced a half-mile or mile apart. Imagine the amount of backtracking that would be required to travel in the opposite direction, and all of the pressure that this would put on residential streets.

No.

But not for lack of trying. Traffic engineers have gone over and over the timing of the signals at Eagle and Franklin. The intersection is different from the other intersections on heavily used, highly developed Eagle/Idaho 55 because backups on northbound Eagle at Franklin have extended onto westbound Interstate 84 during the evening commute.

The goal is to avoid putting drivers in that dangerous situation, which is why Eagle gets generous green light time and Franklin doesn't. Even taking five seconds from northbound Eagle's green light for Franklin would have drivers waiting on the freeway.

The arrangement might be tolerable except that St. Luke's Meridian Medical Center is near the intersection. Emergency vehicle drivers can override traffic signals on their way to the hospital to give themselves green lights and display red lights for other travel directions. Recently ACHD recorded more than 20 such signal preempts at Eagle and Franklin in a single day.

Preempts can happen when the emergency vehicle is a half-mile away. Many times, sirens are silent and emergency lights are left dark, depending on the patient's condition. Once the emergency vehicle is gone, it can take a few signal cycles to get traffic moving normally again.

A frustrated driver, who now likely has an even longer wait because they were skipped due to the preempt, may not realize an emergency vehicle disrupted the carefully coordinated signal timing at Eagle and Franklin.