Tunnel Area Historic Passes and Roads
From "California Highways, A Descriptive Record of Road Development by the State and by Such Counties That Have Paved Highways" by Ben Blow, H.S. Crocker Co., San Francisco, 1920
The Tunnel area was, and is, the location of the the old grade (Cuesta Viejo - also called the San Fernando Pass) on the Old Road (Camino Viejo), Beale's Cut (new San Fernando Pass), and the Newhall tunnel/cut (Newhall Pass). At times, all of these are called the San Fernando Pass or the Fremont Pass or the Newhall Pass.
The passes have a similar history. Each one became inadequate for the transportation of the time - first wagons and then automobiles. The freeways (SR-14 and 5) provided the last solution to the bottleneck at the Newhall pass.
I do not cover the freeways here, although SR-14 does pass through the Tunnel Area and is located on top of some of the early oil wells. The portion through the Tunnel Area was completed in 1972 and was opened between 1973 and 1975 (after 1971 quake delays).
The best source for the history of the passes is "The San Fernando Pass and the Pioneer Traffic that Went over It" (in four parts) by Vernette Snyder Ripley, The Quarterly of the Historical Society of Southern California; March 1947, Vol. XXIX, No. 1 (Part I); September-December 1947, Vol. XXIX, No. 3-4 (Part II); March 1948, Vol. XXX, No. 1 (Part III); June 1948, Vol. XXX, No. 2 (Part IV). These can be found at the Santa Clarita Valley History in Pictures website.
California Highways and Public Works, March-April 1964, inside front cover
California Highways and Public Works, March-April 1964, inside back cover
The following is from California Highways and Public Works, September-October, 1954