This existing intersection between two rural highways seems to have a higher crash rate than it should for an intersection of its busyness. As a class project, our student group designed the intersection. While our design was not real, in the sense that it would ever be built, our design attempted to follow geometry requirements from the American Association of State Highway Transportation Officials (AASHTO).
The other five student groups made improvements to existing T-intersection along US-6. Our student team considered the regional significance of the highway (US-89) marked in red. It appears the highway once continued straight into the canyon (left edge of photo). At some point in the past, the state realigned the roadway into a T-intersection to allow US-6 to continue west (right edge of photo).
US-89 is a significant roadway which serves as a principal arterial through Provo, Springville, and Mapleton. If the road was to be connected to Powerhouse Road, it would allow the road to continue and serve the cities of Spanish Fork and Salem, acting as a continuous foothill arterial.
The team agreed that it made best sense to connect these two T-intersection into a single signalized four-way intersection. The required construction of a new railroad grade crossing adjacent to the new intersection.
The vertical elevation change required to clear the railroad will mean introducing quite a bit more fill material along both US-89 and US-6. A design speed of 50 miles per hour was selected, which required significant land purchasing for the wide turn the proposed roadway will make. Utah has a lower maximum superelevation than warm-weather states, which means a wider turn radius for the design speed.
Class and professor feedback during our team’s presentation helped us consider a few issues and improvements which were not included in our original design:
- Future plans for US-6 may include interchanges, which would make an at-grade signal inappropriate
- The vertical drop between the railroad structure and the intersection provides adequate stopping distance for semi trucks if there is no queue at the signal, but is inadequate when a queue is present.
- The design should incorporate grade crossing over US-6 with ramps to compensate for stopping distance issues
- Design if probably too expense to be practical