Why Truckee has so many roundabouts and how they may be helping traffic
The Sierra Sun did not analyze traffic accidents at the intersections where roundabouts exist on Highway 28 in Kings Beach or Incline Village for this story, due to the roundabouts only recently existing.
TRUCKEE, Calif. — During the slow seasons, they operate like a well-oiled machine, but on a bluebird ski weekend, expect to hear plenty of horns honking as out-of-towners nervously attempt to navigate through traffic in the region’s roundabouts.
There are roundabouts in a few places in North Lake Tahoe, but for several years, the tiny 16,000-person town of Truckee has seven of them within its boundaries alone — and more are planned.
Roundabouts are supposed to reduce the number and severity of traffic collisions, but the majority of Tahoe-Truckee area’s traffic comes from out-of-town visitors who may not be used to circular intersections.
“Ten years ago when the master plan was redeveloped, the town adopted a policy that was that we shouldn’t install traffic signals, but roundabouts,” said Truckee Public Works Director Dan Wilkins.
Wilkins is an engineer who’s been with the town for 19 years, so he’s been involved with the construction of all of Truckee’s roundabouts. He said they’re safer and more efficient because of the seasonal nature of the region’s traffic.
ALTERNATING TRAFFIC PATTERNS
“What happens is because of the high visitation in the summer months, you’ll have intersections that would require signals in the summer but not in the winter because the volume is lower,” Wilkins said.
The idea behind the roundabout is simple: cars approach the intersection and yield to the vehicles already in the circle. If there are no cars in the circle, or there is a large enough gap, the driver proceeds.
“If you put a traffic signal in an intersection when there’s no need for a signal, it actually creates a delay,” Wilkins said.
This is because if there are no other cars in the intersection, the driver at the stop light still has to wait, which is inefficient during times of the year when traffic is slower, like Tahoe-Truckee’s shoulder seasons in the spring and fall.
“A well-designed traffic signal will have detection and try to adjust its timing to adapt to the traffic flow, but it’s not as efficient as a roundabout.” Wilkins said. “With a roundabout, each driver is waiting for a gap, so each driver is using space as it becomes available, whereas a signal will cause traffic to be stopped even if there is no traffic on the mainline, and we’ve all been there.”
SAFETY IN CIRCLES
The other reason more roundabouts are being built is safety, since they’ve been proven to reduce the number and intensity of traffic collisions.
“The types of accidents tend to be fender-bender types of accidents, whereas other intersections have higher-speed collisions,” Wilkins said.
An analysis of traffic collision data, collected from the University of California, Berkeley, Transportation Injury Mapping System for the 10-year period between 2005 and 2015, confirms that roundabouts are associated with fewer reports of collisions in Truckee.
Though the rates vary, and are somewhat scattered, every intersection with a roundabout has had a decrease in the number of accident reports.
There are a few reasons for this. For one thing, city planners like Jeff Speck, author of the book “Walkable City,” have noticed that when drivers are less certain about how to proceed, they drive more carefully — this might explain why downtown Truckee’s infamous four-way intersection with a three-way stop at Donner Pass Road and Bridge Street hasn’t had more accidents.
The other reason roundabouts seem to have fewer collisions and less intense ones is that drivers are incapable of passing through at a high speed.
“You’ve got a higher likelihood of a high-speed collision at a traffic light intersection than you do at a roundabout,” Wilkins said.
Vehicles can only travel about 15 to 25 miles per hour in a roundabout, he said, but at certain traffic signals in town, like the one at Brockway Road and Highway 267, drivers approach the intersection at around 50 miles per hour.
Wilkins also said that the types of injuries and the frequency of injuries, at intersections with roundabouts, is less than a typical intersection.
That’s because if someone runs a red light, and is travelling at 50 miles per hour and hits another car, the impact is greater than it would be if they were driving 25 miles an hour through a roundabout.
APPEARANCE AND FUTURE PLANS
The final reason Wilkins provided for the town’s use of roundabouts is the way they look.
“The third benefit is the aesthetics,” he said. “Roundabouts tend to be more visually appealing.”
At certain intersections in town, like the roundabout located at Pioneer Trail and Donner Pass Road, art installations have even been added.
All seven of the town’s roundabouts were constructed between 1998 and 2011. They are located at the intersections of McIver Crossing and Donner Pass Road; Martis Valley Road and Brockway Road; Donner Pass Road and State Route 89; Prosser Dam Road and Henness Road; Donner Pass Road and Pioneer Trail; and at the intersections of SR-89, Prosser Dam Road and Alder Drive.
There are four more tentatively planned to be built within the next few years, located at Donner Pass Road and Interstate 80 at the Coldstream interchange; Northwoods Boulevard and Donner Pass Road; SR-89 and Donner Pass Road; and potentially at the intersection of Stockrest Springs and Donner Pass Road.
Wilkins said that the SR-89 and Donner Pass Road roundabout is roughly 5 or 6 years away from build-out, but there is no date set for that project yet.
The Stockrest Springs and Donner Pass Road roundabout is contingent on the construction of the Coburn Crossing development proposed for the Barsell property, which is still under review.
Residents and visitors alike can expect to see a roundabout built at I-80 and Donner Pass Road, at the Coldstream interchange, by roughly 2019, according to the town.
As for Northwoods Boulevard and Donner Pass Road, construction is estimated to begin by about 2020.