ACHD's Road Wizard Sunday, May 5, 2019

ACHD recently evaluated adding a separate eastbound left-turn phase to go with the left-turn lane at this intersection. In Downtown Boise, however, signalized intersections operate on a "fixed time" system, which makes that challenging. All things considered, this timing approach is one of the most efficient ways of accommodating traffic flows in an area with closely spaced signalized intersections.

Planning the same amount of green time in the same pattern by time of day also allows drivers to progress through downtown while still allowing enough time for pedestrians to cross the street.

One seemingly small change, such as the introduction of left-turn signals, can have far-reaching impacts on how the signals interact. In other words, if time is added for a left-turn phase, that has to be taken from another direction of traffic that may experience significantly longer delay as a consequence.

A left turn signal for State at 8th Street may reduce delay for this specific movement, but it sacrifices traffic progression along State and introduces delay to other parts of the system. At this specific intersection, a left-turn arrow would have significant consequences.

But there is good news for signal timing in the area. ACHD updated timing throughout Downtown Boise in 2017 (about 130 signals). An analysis which was done after the revised signal timings went into effect found a travel time reduction on State between 5th and 18th streets in the peak travel direction of between five and 10 percent. This amounts to an average of about 20 seconds of time saved per vehicle during rush hours.

There are many "starts" in major road projects. The stakes indicate the start of right of way purchases along Chinden/U.S. 20/26 in preparation for the Idaho Transportation Department's widening of the rural/not-rural-for-long route between Boise and Caldwell.

The start of actual construction is planned for early 2020. That same year, ITD will build additional lanes from Meridian Road to Highway 16. The section between Meridian Road to Locust Grove Road is planned for 2021 construction.

ACHD owns/maintains some of this odd paved area, which provides the businesses along the river public street access. ACHD filled the pothole this week, but the rest of the pavement is not high on the work list.