Needle's Eye Tunnel Repair Feasibility Study

The Needle's Eye Tunnel is located at elevation 3536 m (11,600 ft) near the top of Rollins Pass on Boulder County Road 117/US Forest Service Road 149 approximately 32 km (20 miles) west of Rollinsville, Colorado. The location of the Needle's Eye Tunnel is shown on Fig. 1. The curved tunnel is approximately 46 m (150 ft) long, 6.7 m (22 ft) wide, and 7.3 m (24 ft) tall. A sketch of the plan and profile is found in Fig. 2. The tunnel was blasted through a mixture of granite and gneiss, typical in the Front Range of the Rocky Mountains. Current ground support consists of rock bolts and wire mesh. During the 20^th century, the tunnel was part of a railroad and vehicle road alignment. Since 1990, the tunnel has been closed to traffic. In 2012, Deere and Ault Consultants, Inc. (D&A) was hired by the Rollins Pass Restoration Association (RPRA) to evaluate the feasibility of repairing the tunnel so that it could be re-opened for low volume vehicle and pedestrian traffic between Rollinsville and Winter Park. The evaluation by D&A showed that the tunnel is currently unsafe for traffic, but could be rehabilitated with a mixture of shotcrete, rock bolts, and drains.