How will access to US 12 work?
Shephard Way will connect to North Street with a simple curve, routing traffic to the existing traffic signal at 18th Street. A new traffic signal will be constructed at Nicole Street which will intersect US 12 to form a four-way intersection. It will also provide a new south frontage road connection (North Street) that ties into Tricia Street.
Why choose a roundabout?
A roundabout is planned at the North Street and Lola Street intersection to accommodate the increased area traffic due to developments to the north, to improve traffic operations and intersection safety, and to help reduce vehicle speeds on the frontage road.
Roundabouts reduced injury crashes up to 75 percent at intersections where stop signs or signals were previously used for traffic control, according to a study by the Insurance Institute for Highway Safety (IIHS).
What types of crashes do roundabouts reduce?
Roads entering a roundabout are gently curved to direct drivers into the intersection and help them travel counterclockwise around the roundabout. The curved roads and one-way travel around the roundabout reduce the possibility and severity of T-bone and head-on collisions. Low speeds associated with roundabouts allow drivers more time to react to potential conflicts, also helping to improve the safety performance.
- A roundabout in Helena at the intersection of Canyon Ferry Road and Lake Helena Drive reduced crashes by 70% and eliminated fatalities over a five-year period.
How will trucks pulling car haulers, school buses and emergency vehicles use the roundabout?
MDT has worked with the local trucking industry to optimize the design of roundabouts for large trucks and other oversized vehicles such as school buses, RVs, equipment, and horse trailers. This roundabout has been designed to fit within the context of the neighborhood and the lower volume roadways leading into the roundabout, while still accommodating larger vehicles when they need to use this route. The slightly raised interior section of the roundabout, containing colored and patterned concrete, is called a truck apron and larger vehicles are encouraged to use the truck apron to be able to safely drive through the roundabout. The back wheels of the oversize vehicle can ride up on the truck apron so it may easily complete the turn, while the raised portion of concrete discourages use by smaller vehicles.
What about pedestrians and bicyclists?
The project provides new accommodations for non-motorized users including marked crosswalks and ADA compliant curb ramps, and improves non-motorized connectivity from Shephard Way to the existing US Highway 12 (US 12) pathway. Currently, there are no pedestrian crossings at US 12 in the 1.5 mile long stretch from 18th Street to Crossroads Parkway. The new traffic signal at Nicole Street will provide a new pedestrian crossing, reducing the distance between crossings along US 12 to less than a mile.
The roundabout makes things easier for pedestrians and bicyclists too. The slower speeds and one-directional traffic flow in a roundabout limit crossing conflicts and give vehicles, cyclists, and pedestrians more time to react to one another.
Who is paying for the improvements?
This project is paid for with Federal Highway Safety Improvement Program (HSIP) funds and the state match funds required to receive the federal funding. HSIP funding can only be used for safety improvements that address an identified safety problem – in this case a high frequency of vehicle crashes.
When is construction?
The project design is about 60% complete and will be finalized over the next year. Construction is planned for 2025.