Daylighting a tunnel is to remove its "roof" or overlying rock and soil, thus exposing the railway or roadway to daylight. This could also be seen as converting the tunnel to a railway or roadway cut. Tunnels are often daylighted to improve vertical or horizontal clearances, for example to accommodate double-stack container trains or electrifying rail lines, where increasing the size of the tunnel bore would be impractical.
List of Daylighted Tunnels
- United States of America
- Auburn Tunnel on the Schuylkill Canal, daylighted in 1857
- Tunnel No. 5 on the Alaska Railroad's Seward-Anchorage line
- Tunnel No. 5 on the Virginia & Truckee Railroad at Nevada S.R. 341 near Virginia City
- The Gwynedd Cut on the North Pennsylvania Railroad, near North Wales, Pennsylvania, built as a tunnel between 1853 and 1856, daylighted in 1930 when the Reading Railroad electrified the line
- A number of tunnels were open cut for the National Gateway project including:
- F. C. Weeks et al., "Tunnel 'Daylighting' on the Alaska Railroad," Transportation Research Record No. 1119, Geotechnology (1987).
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