An interchange will provide safer access to Aht'Wy Plaza residents and local businesses.
A full grade separated interchange is planned for the east entrance with design expected to be completed next winter. Once the Nez Perce Tribe secures funding for construction, the project can go to bid soon after. After the structure is built, the Idaho Transportation Department will assume ownership and maintain it as part of the public transportation system.Read More
The interchange will be constructed near the current east entrance. A bridge will be built over US-12/US-95 to allow for safer travel to and from Aht’Wy Plaza. Four ramps with acceleration and deceleration lanes will allow traffic to exit and enter the highway.
The four lanes of highway below will be separated by concrete barrier, eliminating the existing median, turn lanes and acceleration lanes, to make room for ramps in ITD right of way and avoid environmental impacts. North of the interchange, the grassy median will remain. Retaining walls will be built to support the elevated ramps.
The parking area just north of the east entrance will be shifted south to provide the Army Corps of Engineers access to maintain the nearby wetland mitigation site for the Lower Granite Dam (labeled as the goose pasture). The old parking area will be restored with natural vegetation.View 2017 concept drawing
The audit team issued a final report in February 2019 detailing several options to improve safety. The report shows that, based on crash data from 2008 to 2018, 1 percent of crashes statewide results in a fatality. Near the plaza, that rate jumps to 9 percent. The trend continues for other types of crashes resulting in injuries ranging from incapacitating to suspected but not visible.Final report and ITD response
Seven people have died near the plaza since 1996. Between 2012 and 2017, there were 12 crashes at the west entrance and six at the east entrance directly tied to movements to and from the plaza. Most crashes at the entrances have been related to drivers exiting the plaza and failing to yield to oncoming traffic when turning left, prompting the 2017 improvements to the west entrance.
For further analysis of crash data beyond the latest improvements and the road safety audit, ITD’s Office of Highway Safety identified other locations and a road type to compare to based on the volume of traffic, proximity to at least one intersection, the number of lanes and median type. These locations were from all over the state, and data was collected within a mile of the selected location from 2008 to 2017 (with some partial 2018 data).
Of the four locations and road type this intersection data was compared to, it had the greatest rate of crashes per 100 million miles traveled. In fact, the rate was nearly three times greater than these other sites for crashes resulting in fatalities and serious injuries.
The road safety audit team provided the final report in February which included a range of options that could be constructed in advance of the planned interchange. Both NPT and ITD are moving forward with options for the east entrance, which include adding an acceleration lane for eastbound traffic and widening the westbound right turn lane to create separation between turning and through traffic.
Work on these interim improvements could begin in spring when weather conditions allow for quality paving and once funding is secured.
ITD hosted a road safety audit to develop other short-term solutions that could be implemented before construction of the interchange. The audit provided NPT several options to pursue with ITD, which will be further detailed in a final report scheduled to come out in February.Initial results news story