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Tehachapi Loop: A marvel of engineering and the laborers who built it

BAKERSFIELD, Calif. (CN) — On a sunny early summer afternoon, I’m leaning over the wood railing at the Tehachapi Loop Overlook hoping for a train. Twenty minutes have passed, and I’m about to leave before I get sunburned when I hear a horn blast in the distance. Then another.

Several minutes later, a train pulled by three orange BNSF locomotives rounds the top bend of the loop.

To my surprise, another train emerges from the tunnel at the bottom of the loop at the same time. As the two trains near each other, the one coming down the loop comes to a stop and allows the one going up to pass.

“Wow, two trains at once,” my husband, who grew up in Tehachapi, says.  “I don’t think I’ve seen that before.”

As one of the busiest rail corridors in the United States, seeing multiple trains on the Tehachapi Loop at once is actually quite common according to Daniel Cronquist, senior engineer with AECOM in Bakersfield and a fellow with the American Society of Civil Engineers.

Though Union Pacific owns the railroad after its acquisition deal with Southern Pacific was finalized in 1996, BNSF has trackage rights. Anywhere between 30 to 50 freight trains use it each day, with various sources listing various numbers.

Due to this heavy traffic, Union Pacific and BNSF teamed up with Caltrans in 2013 to improve the line with segments of double-tracking and improved siding. Completed in segments with and finally finished in 2020, the upgrades allow more — and longer — trains on the line.

The train that stopped on the loop to let the other train pass by was using this double-tracking. The choice of which train slows down to let the other pass depends on the railroad corporations, which factor in variables like cargo and scheduling demands to determine which train gets priority, Cronquist said in a phone interview.

Once the train going up the loop disappears behind the mountainside, the train going down continues on its way. Roughly 30 minutes later the last shipping container vanishes into the tunnel.

Built in the 1870s to connect the Central Valley and Southern California lines of the Southern Pacific Railroad Company, the roughly 3,800-foot Tehachapi Loop is the brainchild of civil engineer William Hood and his assistant engineer Arthur De Wint Foote.

The engineers knew they needed to go east from Bakersfield through the Tehachapi Mountains toward Mojave, but the difficult terrain and the need to make a steep rise in elevation at a grade the train engines of the time could manage posed significant problems.

Hood's solution was to design a loop. After exiting an approximately 430-foot tunnel, a train circles clockwise around a conical mound at the center of the loop, gaining 77 feet in elevation over a gradual incline at what Brett Hansen, writing for the American Society of Civil Engineers in a 2010 article, called a "steep but manageable" 2.2% grade. Any train longer than 3,800 feet — about 56 box cars — passes over itself going around the loop, always a thrill for trainspotters.

After its completion in 1876, the loop was the first of its kind in the world. Today it is considered "one of the seven wonders of the railroad world," according to the historical marker erected in 1953 when the loop was designated a California Historical Landmark. A little over 30 years later, the loop was designated a National Civil Engineering Historic Landmark in 1998 by the American Society of Civil Engineers (ASCE).

The dedication plaque erected in October 1953, when the Loop was designated a California Historical Landmark. It bears no mention of the Chinese laborers who physically constructed the Loop. During the 1950s, U.S. immigration law still limited the number of Chinese immigrants to 105 a year via the Magnuson Act. Enacted in 1943, the Magnuson Act repealed the 1882 Chinese Exclusion Act when China became an ally of the United States against the Japanese during WWII.

Though Hood and Foote typically get all the glory for this marvel of engineering, the loop and the Tehachapi Line itself would not exist without the blood and sweat of the roughly 3,000 Chinese workers who "cut through solid and decomposed granite using nothing more than picks, shovels, horse-drawn carts, and blasting powder,” the 1998 dedication plaque for the loop states.


Thousands of Chinese immigrants, mostly from the Guangdong (Canton) province in southern China, came to the United States during the Gold Rush. They arrived in the Kern River Valley in the late 1850s and early 1860s, where they worked the mines for white claim owners before being allowed to have claims of their own. Most miners left the area after a flood in 1862, but the Chinese stayed put. A year later, their population in Kernville (a small town roughly 52 miles northeast of Bakersfield) had grown to around 500, according to a 2010 article in The Bakersfield Californian.

In the late 1860s, Chinese came to Havilah and Tehachapi in eastern Kern County to mine borax. Others worked on ranches, as domestic help for white families, or opened businesses in the various Chinatowns in the area. Bakersfield had the distinction of being one of the few towns to have two Chinatowns — Old Chinatown and New Chinatown, whose residents came from different areas in Guangdong and spoke different dialects. Though they worked together in the mines and on the railroad, the groups rarely mixed socially and often disagreed with each other, according to Californian article.

Many of the immigrants who worked on the Southern Pacific railroad were veterans of the better-known Transcontinental Railroad, which connected the cross-country Union Pacific and Central Pacific lines at Promontory Summit, Utah, in 1869. Workers on the Transcontinental Railroad and Southern Pacific line both braved environmental hazards like rock avalanches and cave-ins as well as dangerous working conditions, in large part from using volatile black powder to blast through mountainsides for tunnels.

"The work excavating the tunnels [for the Tehachapi Loop] was extraordinarily dangerous," Hansen wrote. "The material encountered included solid granite, decomposed granite, and soft soil. As a result, cave-ins and other accidents were common. On March 30, 1876, 12 Chinese workers were buried after a charge of black powder exploded prematurely. Three days later five kegs’ worth of powder exploded in another tunnel, killing nine and wounding several others."

Five hundred workers quit after these disasters struck, but chief of construction J.B. Harris convinced them to keep working by having a second group follow the excavation team to install temporary timber supports, according to Hansen's article.

As if these dangerous working conditions were not enough, the workers also contended with bigotry. Chinese workers on the Transcontinental Railroad were paid less than their white counterparts and had to buy their own food and find their own shelter, while white workers were given room and board. They were also disproportionately given the most dangerous tasks, and several hundred died in industrial accidents.

Since most of the workers on the Southern Pacific Line worked on the Transcontinental Railroad, it's no big stretch to think they suffered the same prejudices. Nevertheless they persevered, and the Tehachapi Pass railroad line arrived in Mojave in 1876.

"This line was part of the last and final link of the first railroad line connecting San Francisco to Los Angeles," the 1998 ASCE dedication plaque states. "It was a primary factor in the early growth of the city of Los Angeles and the state of California."

With the Tehachapi line complete, many of the Chinese railroad workers stayed in Kern County and became farmers, ranchers and oil field workers.

One of the most successful was Leong Yen Ming. Born March 13, 1858, in Say Yup China, he helped build the Tehachapi Loop before turning to agriculture. In addition to opening the first school for Chinese children in Bakersfield in 1912, he was also known as the Chinese Potato King. In 1916 , he received $10,000 for his entire crop — the highest purchase price in the county for that season.

Ming died in 1941 at the age of 83. Today, the Valley Plaza Mall is located where his ranch once stood, and the street it is on is named after him: Ming Avenue.

That the Tehachapi Loop is still in constant use almost 150 years later "attests to the superior job of both engineering and construction done by the two civil engineers and the Chinese laborers," the 1998 ASCE marker states.

"This plaque is dedicated to them."

For more information about the Chinese workers who built the Transcontinental Railroad, check out the fantastic Chinese Railroad Workers in North America project organized by Stanford professors Gordon H. Chang and Shelley Fisher Fishkin. Active from 2012 to 2020, the online archive is devoted to giving these unsung heroes of the railroad faces and voices through oral histories, interviews and photographs.

This plaque was dedicated in 1998 when the American Society of Civil Engineers designated the Tehachapi Loop as a National Historic Civil Engineering Landmark. Unlike the 1953 plaque, this one not only mentions the contribution of the Chinese laborers but is dedicated to them and the engineers. (Rebekah Kearn/Courthouse News)
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