At a little over 17 feet wide, the Newhall Tunnel could only barely allow 2 cars traveling in opposite directions to pass. The traffic situation was becoming unbearable at the tunnel and a solution was needed.
The LA Times of April 17, 1927, reported that the Newhall Masonic Club has started a movement to secure the aid of the State Highway Commission in providing relief from the congestion of traffic at the tunnel. The Sunday traffic of April 10 was lined up and practically at a standstill for 6 miles from the mouth of the tunnel to Newhall. Two means of relief were suggested. The present tunnel could be enlarged or Beale's cut could be returned to use if the pass was widened and deepened. The second plan actually had the most attention in Newhall.
From the LA Times of May 4, 1927: "On Sundays and holidays automobiles are often lined up from the northern portal of the tunnel to the very outskirts of Newhall waiting an opportunity to pass through." "It is so poorly lighted that a driver plunging into the darkness on a bright day is confused and forced to steer almost by instinct." "It has no provision for pedestrian traffic." "On a recent Sunday 19,000 automobiles squeezed throught the Newhall tunnel between 6 a.m. and 10 p.m., according to a census taken by State traffic officers." "It is time for State highway officials to devise means for widening the tunnel."
LA Times of June 19, 1927: "The plan that probably will be adapted, according to advices reaching the Automobile Club of Southern California, is to parallel the present road on the west for a distance of several miles in the vicinity of the Newhall tunnel."
In 1930, a three-lane highway through Weldon Canyon Road was completed by the California Division of Highways. This would be the same route as the Golden State Freeway many years later. Congestion was temporarily relieved through the Newhall Tunnel. (See story below.)
In the January, 1938, issue of California Highways and Public Works magazine (and you can read it below) it is stated:
Recognizing the necessity for some sort of relief at the tunnel bottleneck, studies have been underway for some time, looking into the most logical solution from an economic standpoint of this troublesome problem. The engineering studies conclusively proved that the elimination of the tunnel completely by the construction of an open cut in place of it on approximately the same line was the cheapest and best method of carrying out roadway widening through the Fremont Pass Ridge. This, of course, will involve considerable excavation material, about 300,000 cubic yards in all, which material in turn must be disposed of in some economical manner.
The whole project would include straigtening and widening the road from Tunnel Station (near today's intersection of the Old Road and Sierra Highway at the junction of the 5 and 14 freeways) to Solamint (today's intersection of Sierra Highway and Soledad Canyon Road). A new road would be built from today's intersection of Sierra Highway and Newhall Avenue to Solamint, the first part of the Mint Canyon Short Cut Route. $900,000 was allocated for the project in January of 1938.
On May 5, 1938, the state awarded a contract for construction and improvement of the highway between Tunnel Station and Placerita Canyon to the Griffith Company of Los Angeles. From Tunnel Station to the intersection of Sierra Highway and Newhall Avenue, the construction would follow the existing road. From there, a new road would be built to Placerita Canyon. The construction from Placerita Canyon to Solamint was part of a different contract.
To protect the traffic through the tunnel during the construction, 30-foot wooden extensions were used first at the north portal and then at the south portal. When the cut was deep enough, ramps were constructed from the existing road to above the tunnel. No blasting was done in the removal of the upper 120 feet. It was loosened with machinery and bulldozed down. At 60 feet above the tunnel, drilling and blasting was done. Since the general dip of the rocks is to the west, at this point they had problems with landslides on the east side of the cut forcing the angle of the cut to be increased. This more than doubled the amount of material that had to be removed. Read more about the construction of the cut in the January issue of California Highways below. The entire project cost $475,700.
I have not found a date that the project was completed, but by the end of 1939, the new, improved road was opened to traffic.
Note: California Highways and Public Works magazine provided important source material here. Issues from 1924 to 1967 (when publication ceased) can be downloaded from the internet at the Internet Archive site.
From the Los Angeles Times of April 17, 1927
From the Los Angeles Times of May 4, 1927
From California Highways and Public Works of May-June 1928
From the Los Angeles Times of July 1, 1928. Construction on the Weldon/Gavin Canyon road will be started soon.
Article from California Highways and Public Works magazine of July-August 1930 reporting on the completion of the Weldon Canyon Road. Many years later this road would become the Golden State Freeway. Note that it says a second tunnel running parallel to the existing tunnel is planned within the next two or three years. This obviously never happened.
The below article is from the California Highways and Public Works magazine of January, 1938
From the Los Angeles Times of September 3, 1938
From the Van Nuys News of October 20, 1938
The below article is from the California Highways and Public Works magazine of November, 1938
The below article is from the Engineering News Record of 2/23/1939. The top photo is the south portal and the bottom photo is the north portal.
The below article is from the California Highways and Public Works magazine of January, 1940
At ground level. Obviously, the shell will be removed and not buried, as was speculated by some people.
This image is NOT in the public domain. It is owned by Brad Therrien and used with his permission.
Looking south down the new cut. From The Twelfth Biennial Report to the Governor of California by the Director of Public Works: July 1, 1938, to June 30, 1940, p.18.
Photograph dated December 11, 1948.
From the Los Angeles Public Library, Valley Times Collection
Similar view as the above image (in 2010). The road was Route 23 and then Route 6 before becoming Sierra Highway
Close-up. In 2010, this sign was either removed by the highway department or stolen.
Newhall cut today (2010) looking north. The cut has been widened over the years.