Diamond in the rough
Construction continues to transform the front yard of Pocatello and Chubbuck, where U.S. 91 and Interstate 86 meet.
The new diverging diamond interchange -- the first to be built in Idaho -- replaces the existing bridge and will increase capacity and safety of the existing structure. The result will be less congestion and fewer crashes. The need became apparent as the existing bridge approached the end of its life span. Replacing the old bridge created an opportunity to examine traffic flow and increase capacity.
Design started in 2010 with the introduction of the alternatives. Modeling and preliminary costs for a standard diamond, a wide diamond and a diverging diamond were presented to ITD. A single-point urban interchange initially was considered but was dismissed because less expensive alternatives operated adequately for 35 years or more.
Of the three alternatives modeled, the diverging diamond interchange emerged as the most effective and efficient option. It allowed the construction of the interchange within the existing right of way and incorporated new construction that had been done in 2010 on U.S. 91 and two of the interchange ramps.
Construction is expected to be complete by the end of November.
For an ITD In Motion video about the interchange, CLICK HERE.