The new traffic signal at State Highway 55 and the Banks-Lowman Road is working as intended, according to the Idaho Transportation Department. Drivers over the busy July 4th weekend encountered delays headed northbound as the weekend began, simply due to the volume of traffic, said ITD District III Traffic Director Justin Price.
“The signal itself, it performed as we'd expect,” he said. “Actually, probably even a little bit better than we expected.”
The signal was installed primarily to address Sunday backups of southbound traffic on Highway 55 and drivers on Banks-Lowman road waiting to make a left turn to join that traffic flow. ITD in recent years has deployed flaggers to the busy intersection on summer Sundays.
More than 10,000 vehicles traveled south on Highway 55 each August Sunday in 2024, according to ITD. About 65% were counted between 11 a.m. and 6 p.m. Holiday weekends are typically even busier. ITD data show northbound traffic through the 55 corridor is split between Friday afternoons and Saturday mornings.
As I traveled east on Banks-Lowman road around 1:30 pm Sunday afternoon July 13, the line of cars waiting to turn onto highway 55 extended 3.5 miles up the road. The signal is more efficient and safer than human flaggers, but isn’t a panacea for the volume of drivers trying to funnel through the only highway back to the Treasure Valley.
Price said feedback since the signal went live before the Memorial Day holiday has been positive.
“People are saying it's working well, they're not having issues. They understand what's happening when they get to the signal and they're able to plan for it. And it's consistent. So it's been overall very positive” he said.
How signals are managed
The new signal on SH-55 is sensor-based, with both camera and radar sensors. The redundancy is to ensure it can continue to work as expected even if one of the sensors has a problem. The camera isn’t currently networked to ITD’s system, so it cannot be remotely controlled. Engineers visit the site each week during the summer to grab an SD card with data.
“We're collecting it in case there's an issue that comes up, we know we have at least 30 days of data where we can go back and look and see if something's not functioning correctly,” Price explained.
They don’t do that with every signal, but have been paying close attention to the new signal since it became operational. They hope to get the location connected to their network in the future, but Price doesn’t expect the ability to monitor the signal in real time would change how it operates.
“The overall goal is to try to use all of the green time that we can during congested times,” he said. That’s not much of a problem on a busy weekend afternoon.
Drivers should expect congestion this summer
Even outside of the peak travel times, drivers traveling the Highway 55 corridor should expect delays. Sealcoating is underway between Horseshoe Bend and Banks, with weekday lane closures and pilot car escorts planned in work zones through early August. There are multiple other work zones on the highway, but work is typically stopped by noon each Friday to keep the highway as open as possible for weekend travelers.
Between McCall and New Meadows, work continues on the Little Goose Creek bridge. Drivers should expect reduced speeds and intermittent flagging for most of construction, and later this summer, lane closures managed by temporary traffic signals.
And ITD continues to prepare to replace the Rainbow Bridge over the Payette River. A new bridge is planned slightly upstream of the current bridge, which was built in 1933 and no longer meets state highway standards.
Officials plan to share design plans for the new bridge at a public meeting July 22 at the American Legion Post in Cascade. There’s more information at sh55rainbowbridge.com.
Construction on the new Rainbow Bridge is expected to begin in 2028.
