I-70 Twin Tunnels (CM/GC Delivery)

The purpose of the Twin Tunnels project is to immediately improve highway safety, mobility, and operational capacity in the eastbound direction of the I-70 Mountain Corridor in the Twin Tunnels area. This project represents the first phase of roadway improvements approved by the I-70 Mountain Corridor Programmatic Environmental Impact Statement (PEIS) Record of Decision and will be implemented in a manner consistent with the I-70 Mountain Corridor Context Sensitive Solutions process and other commitments of the PEIS.

The work for this project will include widening the eastbound bore of the Twin Tunnels to allow construction of a third lane of traffic to be added from East Idaho Springs (M.P. 241) and the Bottom of Floyd Hill (M.P. 244). This work includes widening of the east bound tunnel structure F-15-BO to between 51’ and 61’; Construction of a new structure adjacent to bridge structure F-15-BH over Clear Creek to accommodate flattening of the curve; preparation of transitions from I-70 to the old US40/Game Check roadway, onto County Road 314 over the bridge structure CLR314-W0.7, and then returning to I-70 just west of the Hidden Valley Interchange at M.P 243; strengthening bridge structure CLR314-W0.7 to accommodate interstate traffic; and relocate the alignment CR 314 adjacent to bridge structure F-15-BH to accommodate the flattening of the curve.  Additional curve flattening reconstruction, retaining walls, managed lane infrastructure, and restoration of CR314 after use as a detour may be included in the work. The construction cost for the project is estimated to be in the range of $40.0 million to $50.0 million.