Ada County Highway District

ACHD's Road Wizard Sunday, August 18, 2019 ACHD's Road Wizard

Flashing yellow arrow traffic signal for Amity Road; request to re-evaluate the signals at 5th Street and Fort Street.

The Road Wizard Replies

Dear Road Wizard: Will we ever get a flashing yellow arrow to turn left on Amity Road from east bound Federal Way? The current "YIELD TO ONCOMING TRAFFIC" is badly faded and very difficult to read in the mornings when you face the sun. What you really see is a bright green light in the left turn lane which leads one to assume that the oncoming traffic has a red light. Not true! One making that assumption, turns directly in front of oncoming traffic traveling at 40+ MPH. When the westbound lane has a green light, it would be so much safer if the eastbound lane had a flashing yellow light or arrow.


Road Wizard:

It's the green arrow that tells drivers they have the right of way, not the green ball. The green ball means left turns must yield to oncoming traffic--the same as the flashing yellow arrow. Ada County has a lot of intersections a where a green ball is the only indication left-turning traffic ever sees, because they don't have a separate left turn lane or signal.

The left turn from southbound Federal Way onto eastbound Amity Road is on the list of intersections to have the flashing yellow arrow installed. This modification won't change what is expected of the left-turning driver, but studies show drivers comprehend the flashing yellow arrow better than the green ball.

As for the glare, this Wizard lacks the ability to change the Earth's rotation. He humbly recommends sunglasses.

Dear Road Wizard: The light for northbound 5th Street at Fort Street, which is also the exit/entrance for the VA hospital, seems exceptionally long. The east and westbound traffic at that intersection has a very long wait no matter the time of day. Does ACHD have plans to re-evaluate this intersection?


Road Wizard:

Fort Street is part of the more than 130-signal coordinated grid that encompasses all of Downtown Boise and most of the signals to the west. Within this network, Fort Street is the coordinated movement, which means it gets vehicle progression priority over the cross streets.

As such, it gets a minimum amount of time to maintain this coordination, even though sometimes it may not need all of it. That may make it seem like the signal is "stuck", since an individual driver usually can't see the big coordinated picture.

At the 5th Street/VA entrance signal, north and south traffic do have more time allocated during the evening peak period, simply because more traffic is present relative to other times in the day.

"Ghosts in the machine" often apply in these situations. Sometimes a sensor gets a mind of its own when it thinks there is more traffic present on a side street approach than there actually is. ACHD will investigate and make appropriate changes if something is amiss.

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