An approved contractor agreement has brought the Lone Tree overpass project one step closer to completion.
Flagstaff City Council approved a contract with Ames Construction to lead the design and build process. Three construction firm finalists were interviewed by an evaluation committee, with Ames Construction emerging as the top candidate.
The contracting firm is located out of Phoenix and brings experience in large-scale bridge construction as well as a past working relationship with the BNSF Railway.
The voter-approved $72.4 million bridge will extend Lone Tree north over the railroad tracks to Route 66, with completion anticipated by 2026. An additional $284 million is budgeted from a separate proposition for improvements to the Lone Tree Corridor and surrounding areas.
“The goal of the project is to provide a great separated crossing over the BNSF corridor and a future Rio de Flag channel,” said Christine Cameron, Capital Improvements project manager. “[The overpass] provides traffic circulation benefits much like we’ve seen with our Fourth Street overpass.”
The first phase of the design process is expected to begin as soon as this month and will include the preliminary design of the bridge, analysis of BNSF Railway relocations, traffic impact analysis on the Route 66 intersection, preliminary design of the intersection and an economic impact analysis. Early design work is expected to span four months.
The first phase also begins the process of property acquisition. The process will involve extended negotiations and approval from Council, which will seek public involvement in future decisions in this area.
After the initial phase is completed, Council will be presented with a near-complete design when phase two seeks approval.
Project designers will look to balance both vehicular and multi-modal transit for commuters in the surrounding neighborhoods in upcoming designs. A project concept developed in 2010 envisions the bridge consisting of two travel lanes in each direction, a center median and Flagstaff Urban Trail System (FUTS) pathway on the westside of the overpass.
Councilmember Adam Shimoni requested that a FUTS pathway be implemented on both sides of the bridge, supporting Councilmember Jim McCarthy’s comments on the need for dedicated bike lanes.
The concept also shows an overpass connection to Brannen Avenue and a circulation road connecting streets from Elden to Lumber with Butler Avenue, as well as the relocation of a BNSF Railway industry spur. As property negotiations begin and designs are finalized, these additions are subject to change, while the rest of the architecture is expected to remain as planned.
In an effort to create room for the bridge and a future Rio de Flag channel, the railway corridor underneath the overpass will undergo construction to bring the railways level with the Route 66 roadway. Horizontal relocations of the corridor are also planned in an effort to keep the railways active while the overpass is being constructed.
As mentioned, the overpass creates a new traffic intersection at the junction of Route 66 and Lone Tree. In addition, the corridor section of the project will evaluate a few intersections for new or modified signalization, including Lone Tree and Butler Avenue, Lone Tree and Franklin, and Lone Tree and Sawmill roads.
Construction of the overpass will impact Lone Tree from Butler Avenue to Route 66. Additionally, the project will affect the Lone Tree corridor from Sawmill Road to Butler Avenue and include construction east and west along Route 66 to create new roadways and turn lanes. Additional edge improvement work will take place on east and west along Butler Avenue at the Lone Tree intersection.