Roundabout debuting this spring
This plan by DCI Engineers shows the configuration of Sandpoint’s first roundabout. (Image courtesy CITY OF SANDPOINT)
SANDPOINT — “Hey, look kids! Big Ben! Parliament!”
The line is repeated several times with decreasing enthusiasm as hapless globetrotter Clark Griswold finds himself hopelessly trapped in a busy London roundabout in the 1985 National Lampoon comedy “European Vacation.”
It is doubtless the classic line has been uttered by a few locals since the city opted to go with a roundabout at Boyer Avenue and Larch Street. Certainly, much worse has been said about the city’s first roundabout, which some critics predict will be a disaster for motorists and pedestrians.
But highly detailed multi-modal traffic flow simulation software indicates the roundabout will be able to handle peak volumes for the next 25 years.
“It worked very well,” Assistant City Engineer Matt Mulder said. “Cars weren’t backing up at all. Things were flowing smoothly.”
Research also shows roundabouts are less dangerous than conventional intersections.
“All the data states that even the largest roundabouts are still safer than traditional (intersections), especially two-way stops or signalized intersections just because of the reduced conflict points,” said Victor Salemann, a member of the Institute of Transportation Engineers and the Transportation Research Board’s roundabout task force.
Construction of the roundabout is scheduled to start the first week of April and is expected to last about six weeks, Mulder said.
The roundabout was funded by Super 1 Foods, which is building a store at the Boyer and Larch. The roundabout was designed by DCI Engineers in Spokane, Wash.
The landscaped center of the roundabout will be about 35 feet across and ringed with a “truck apron” that will be about 31 1/2 feet wide. The apron will enable tractor-trailers with wheel bases as long as 67 feet to negotiate the roundabout.
The roundabout’s single traffic lane will average about 16 feet wide. Each approach and exit to the roundabout will be demarcated by raised “splitter islands” with beveled curbs. Each splitter island will be bisected by pedestrian crosswalks.
The advisory speed within the roundabout will be 15 mph.
Salemann said Washington state has nearly a hundred roundabouts.
“There’s general support that this is an improvement — a huge improvement — over two-way stop control conditions, mid-block pedestrian crossings and still a significant improvement over a signalized crossing,” Salemann.
Salemann, an engineer at David Evans & Associates in Bellevue, Wash., said a general goal of roundabouts is harmony.
“One of things we’re looking at doing is to try to balance some of those competing interests of keeping the speeds low and making pedestrian amenities as good as we can,” he said.