Boise & Garden City

Stop turning left at stoplights? Boise project models a new way to drive

See your new way of making left turns on State Street at Veterans Memorial Parkway

State Street is one of Boise's busiest streets. The Ada County Highway District is adopting new designs that eliminate or reroute left turns at intersections. The intersection at State and Veterans will be the first to get a new design that turns
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State Street is one of Boise's busiest streets. The Ada County Highway District is adopting new designs that eliminate or reroute left turns at intersections. The intersection at State and Veterans will be the first to get a new design that turns

Projects to improve State Street in Boise have been in the works since 2004. The street, a key route between Boise and Eagle, is the busiest road in Ada County north of the Boise River.

Construction will begin this fall on one of those improvements — upgrades to the intersection with Veterans Memorial Parkway and 36th Street.

When finished, it will represent more than just one overhauled intersection. The work could set a precedent for future projects along State Street and change the way you make left turns at Boise’s busiest intersections.

Those left turns are problematic, said Craig Quintana, Ada County Highway District spokesman, “because you have to stop opposing traffic, which creates delays.”

The Federal Highway Administration is encouraging designs that curb left turns at high-volume intersections, Quintana said. Transportation agencies, including Idaho’s, are embracing the idea.

State and Veterans will become a “thrU-turn,” also known as a median U-turn or a “Michigan left.” The design gets rid of left turns in the east/west State Street lanes. It’s the first of its kind in the area, according to ACHD, but has been built in Lehi, Utah, and Bloomfield, Mich.

Drivers along State will continue through the intersection, make a U-turn down the block, then head back toward the intersection and and make what becomes instead a right turn.

Left-turning traffic will remain unchanged in the north/south lanes.

A median u-turn design, one possibility for State and Glenwood. Ada County Highway District

The project will begin this fall, but ACHD has not set a construction date, Quintana said.

How else could this look?

Ideas for how to adjust State and Glenwood streets — also on the board for improvements — show other variations on this concept.

The “displaced left turn” design essentially moves the left turn farther back from the intersection. Left-turning cars cross the opposing lanes and drive up to the intersection in their own lane, on the road’s far left side. At the intersection, they then turn left without having to cross opposing traffic.

Displaced left turn, one possible design for State and Glenwood. Ada County Highway District

The “quadrant,” a design that resembles a figure 8, actually sends left-turners the opposite way at first. Cars turn right onto new side roads and make their left turns at a spot away from the central intersection.

A quadrant intersection, one possible design for State and Glenwood. Ada County Highway District

And there’s the status quo: keeping the intersection at State and Glenwood like it is, but adding more lanes.

Current intersection
If State and Glenwood continued under its current approach. Ada County Highway District

State and Glenwood involves both local roads and a state highway, so ACHD and the Idaho Transportation Department are co-hosting a Tuesday open house on these concepts. If you want to submit a comment, visit the Garden City Council Chambers, 6015 N. Glenwood St., from 3:30-4:30 p.m. for adjacent business and property owners, or from 5-7 p.m. for the general public.

Big numbers

The two road agencies will use the public comments to help shape their Glenwood Street and State Street Intersection Study.

“We want people to tell us what they want to see,” Quintana said. A formal proposal for improvements could be ready at the end of the year.

Around 60,000 cars use the State and Glenwood intersection every day. The intersection ranked as the ninth busiest in Ada County, according to ACHD’s most recent 2014 study (Eagle Road at Fairview tops that list). Five bus lines cross the intersection.

State and Glenwood also ranks 45th on ITD’s statewide crashes list. Between 2011 and 2015, 112 reported crashes took place at the intersection. There were no deaths, but nearly half involved injuries.

ACHD and ITD are “taking the long view” of the intersection, Quintana said.

At this time, Quintana said, the delay for drivers at State and Glenwood during peak hours is about 70 seconds. By the year 2040, if no improvements are made, driver delays would increase to around four minutes under the agencies’ growth projections. Crashes are projected to rise by 12 percent.

How do biking, walking fit in?

Along with all those cars, 135 pedestrians and 90 bicyclists use the State and Glenwood intersection. Currently, the only bike lanes near the intersection are on the north side of Gary Lane.

Cynthia Gibson is executive director of the Idaho Walk Bike Alliance, a statewide nonprofit organization that promotes safe walking and biking and other nonmotorized transportation. She said her organization has done audits on State Street and spoken to bikers and walkers, including people who use wheelchairs.

She hopes any new project will include features that make it safer, not to mention nicer, for residents to bike and walk that route — for example, protected bike lanes separating cyclists from traffic.

“With the high numbers of people who walk and bike on State Street, this is an opportunity to redesign the right way,” Gibson said.

Quintana said that any future proposal for the intersection will address the needs of both groups. But it’s too early to say how some of the concepts to minimize left turns will affect infrastructure like bike lanes under ACHD’s approach.

“We have a blue sky here and lots of room for improvement for nonmotorized transportation,” Quintana said, “but we’re still at the concept stage, not anywhere near the brass tacks of design features.”

The “thrU-turn” planned for State and Veterans offers one asset for pedestrians: two additional signaled crosswalks near where cars will make their U-turns. Pedestrians won’t have to walk what Quintana called “the long super blocks” along State Street between signaled crosswalks — or risk crossing without one.

The State and Veterans project will also benefit Veterans Memorial Park users, said Doug Holloway, Boise Parks and Recreation director. The park is located on the intersection’s southeast corner. The parks department worked with ACHD to include a 12-foot-wide concrete pathway into the intersection design that will “meander through the trees.”

“This essentially relocates the sidewalk, which was outside the park, into the park so as to provide a more pleasant experience for pedestrians along State Street,” Holloway said.

What about other State Street intersections?

An improvement project at State Street and Collister Drive is scheduled for the fall of 2018.

Along with State and Glenwood streets, there is an ongoing study of State Street and Pierce Park Lane.

Can’t make Tuesday’s open house but still want to comment?

Find more information about traffic alternatives for State and Glenwood and take a survey on what you’d like to see on the ACHD website, Comments are due by Aug. 30.