|Map of the route of Glenwood Tunnel. (Courtesy Duncan Nanney)|
|Glenwood Tunnel's north portal visible in the background outside the town of Laurel before 1906.|
When completed, Glenwood Tunnel was officially branded SPC Tunnel #3 and was a bore 5,792 feet long, running directly under Highway 17 today. The 1899 Station Book notes it spanning the gap between the 62 and 64 mile posts from San Francisco via Alameda Point. Early photographs of its north portal show that the tunnel had a wood-frame portal, at least on the northern side, until it was upgraded after the 1906 Earthquake. It is highly possible that the southern side, however, had a cement or stone portal early on, as Glenwood Highway, the main thoroughfare over the Santa Cruz Mountains during this period, ran directly over the tunnel's south portal.
The Southern Pacific Company purchased leasing rights to the South Pacific Coast's holdings in 1887 and began upgrading the tracks to broad gauge by the early 1890s. It is unclear if the Glenwood Tunnel was already wide enough to support broad-gauged trains but it was likely expanded during this time. In 1903, Tunnel #1 in Cats Canyon was daylighted because of this construction, and Glenwood Tunnel was renumbered Tunnel #2.
The San Francisco Earthquake of April 1906 did minor damage to the Glenwood Tunnel but timetables from 1907 show through service to Laurel via Glenwood by that year, suggesting that the damage to Glenwood Tunnel was mostly superficial and easily repaired. Upgrading of the tunnel, including the erection of large and sturdy cement portals, began in ernest in late 1908, shutting down the tunnel for at least part of the year, as timetables during this time imply. The imprints above the two portals both read 1909, suggesting that construction was completed early that year. The Glenwood Tunnel was the last tunnel along the Mountain Route to be upgraded to standard gauge.
|Exposed wood plank imprints visible along the top of the Glenwood Tunnel's north portal at Laurel.|
|The re-opening of Glenwood Highway after a major construction project, 1915. The south portal of Glenwood Tunnel cannot be seen in full, but the horses are marching over it at left. (Note the metal barricade along its top).|
|The approach to Glenwood Tunnel's north portal near Laurel, February 29, 1940. Note the sand on the tracks and the debris. The portal, on the other hand, seems to be intact. (Courtesy Bruce MacGregor)|
|Glenwood Tunnel's north portal today.|
|Glenwood Tunnel's south|
|Jeff Escott standing over the 1909 date over the Glenwood Tunnel's South Portal. (Courtesy Jeff Escott)|
|Glenwood Tunnel's south portal as viewed from Glenwood Drive above.|
|Glenwood Tunnel's south portal as viewed from inside. Note the sandy fill and the major steel girders|
supporting the back of the portal. The entrance of the portal is overhead.
- De Leuw, Cather & Company, "Santa Cruz-Los Gatos Rail Corridor Feasibility Study: Draft Final Report" (1994).
- Southern Pacific System: List of Officers, Agencies and Stations, 1899.