Part two of a two-part series
The rugged geography, dense population, and arid nature of Southern California has created the need for some of the most unique and complex tunnel systems anywhere in the world, and over the last 150 years engineers and entrepreneurs have stepped up to meet the demand.
We continue to explore some of the most notable and interesting tunnels in Southern California, with a focus on those built for human travel, and bored or dug through a mountain, hill, or an underground space.
Surprisingly, there are no driving or railroad tunnels in the San Bernardino Mountains, but there is a fascinating and historic water tunnel built in the early 1900s at Lake Arrowhead. While not originally built for human travel, the 4,980-foot tunnel is now open for guided walking tours during summer.
PART ONE: The history of some Southern California tunnels and why they were built
According to local historian Russ Keller, “Tunnel No. 1 was built as a drain system for the reservoir, and the system was completed in 1908. It channels water from the lake’s intake tower and empties into Willow Creek. The Rim of The World Historical Society in Lake Arrowhead gives tours of this abandoned tunnel for its members.”
The Big Horn Mine in the San Gabriel Mountains boasts an impressive 7,000-plus feet of mining tunnels. The gold mine is located on the eastern flank of Mount Baden-Powell, and is about 6.5 miles west of Wrightwood. The extensive tunneling work is surprising since the mine was never a significant gold producer.
The mine was discovered in 1891 by Charles Vincent and N.D. Shippy and it operated in various conditions of mining and exploration until the 1990s. Many of the mine’s tunnels are intact, but they have been closed by the U.S. Forest Service. The remains of the main mining structure still clings to the mountainside.
An excellent hiking trail with magnificent mountain vistas takes you from the Vincent Gap parking lot on Angeles Crest Highway, to the mine site at 6,900-foot elevation.
In December 1925, the Pacific Electric Railway Company opened the Hollywood Subway Tunnel, aka Belmont Tunnel. The tunnel ran 1.04 miles from the company’s subway terminal building in the center of Los Angeles, to its northwest entrance in today’s Westlake district. It took 18 months to build the tunnel at a cost of $1.25 million, equivalent to $22.7 million in 2024.
The Pacific Electric Railway Company operated an extensive electric streetcar system in Southern California, and two-track subway tunnel cut off roughly 8 miles of street-level rail travel through some of the most heavily congested traffic in the U.S.
At its peak, the Hollywood Subway Tunnel carried an estimated 20 million passengers each year. Competition from automobiles and buses reduced ridership on the Pacific Electric Railway Company and brought an end to the system. Operations through the Hollywood Subway Tunnel ceased in 1955. After closing, the tunnel has been used as a set for TV shows, music videos, and movies including “Running Man” and “Predator 2.”
The closed northwest portal to the Hollywood Subway Tunnel has been preserved, and it can be seen at 242 S Toluca St. in Los Angeles.
In the early 1940s, two tunnels were blasted through solid rock in the rugged San Gabriel Mountains for construction of the Angeles Crest Highway. The scenic, winding highway threads its way through the 720-foot and 420-foot tunnels near the Islip Saddle Day Use Area. Located just a few miles north of a highly urbanized area, the road through these tunnels has the feel of a remote alpine region. The tunnels can still be driven through when the seasonal highway is open.
Two tunnels were built on Mount Baldy Road in the San Gabriel Mountains, approximately two miles north of the Mountain Avenue intersection. The lower tunnel completed in 1949, is approximately 630 feet long, and the upper tunnel completed in 1954, is approximately 250 feet. These tunnels are still in use, and the stone-arched portal entrances are great examples of mountain tunnel architecture.
The Boring Company’s Hawthorne R&D Test Tunnel was never open to the public, but it is worth mentioning for its unique, scientific coolness factor.
The Hawthorne Tunnel is a 1.14-mile tubular, underground tunnel that generally stretches around the perimeter of the Hawthorne Municipal Airport. The tunnel was built to test the operation of single automobiles (primarily the Tesla Model X) in a tunnel environment, using guided busway-style, side-facing wheels.
The Boring Company was founded in 2017 by Elon Musk as a subsidiary of SpaceX to construct transportation tunnels that will alleviate traffic congestion. The company uses large tunnel boring machines for construction.
Almost 40 years after the Pacific Electric Railway closed its last subway tunnel, L.A. Metro Rail resurrected the idea of subway tunnels for rail transportation in Southern California.
In 1993, L.A. Metro opened the Red Line subway, now the B Line, that eventually stretched 14.7 miles from Union Station in downtown L.A., to North Hollywood, in the San Fernando Valley.
L.A. Metro’s new D Line subway will run from Wilshire Center, approximately nine miles west, to Westwood. The D Line is expected to be completed in 2027.
Today, L.A. Metro’s subway tunnels connect some of the city’s most densely populated neighborhoods.
There are many other great tunnels in Southern California, along with thousands of important water, sewage, and drainage tunnels crisscrossing the region, but we’ll have to cover those another day.
Mark Landis is a freelance writer. He can be reached at Historyinca@yahoo.com.