Friday, December 13, 2019

Tunnels: Hogsback (Tunnel 7)

Contrary to popular belief, there were actually two tunnels originally located in San Lorenzo Gorge. The first and better known was the Coon Gulch Tunnel under Inspiration Point. But the oldest railroad tunnel in all of Santa Cruz County was actually located 1.3 miles to the south, located beneath the solid granite promontory known as the Hogsback.
The only known image of Tunnel #7 under the Hogsback from a newspaper lithograph, May 1880.
The San Lorenzo River carves a relatively straight south-south-eastward path from its origin in Castle Rock State Park to the Monterey Bay twenty-one miles to the south. But that straight route gets interrupted by the Hogsback, which forces the river to twist awkwardly to the north before wrapping around the rocky outcropping to continue its inevitable journey to the sea. The granite block was named after its appearance, rising above the river like a giant hairy hog's back raised to the sky. And just like the river, the Santa Cruz & Felton Railroad could not get around this obstacle except by going through it.

Indeed, the San Lorenzo Valley Railroad planned to bore a 900-foot-long tunnel through the base of the Hogsback to bypass the obstacle and maintain its even grade up the river, but since the project failed, the tunnel was never bored. The California Powder Works, however, drilled an equally-long tunnel  through the Hogsback to reach its gravity-fed reservoir located on the north side. When the Santa Cruz & Felton Railroad came along, its route was built much higher on the ridge, almost at a level that could simply build over the Hogsback, but the grade was already steep and the promontory was its highest point. To decrease the grade enough so a standard consist could reach the summit, the company decided that a tunnel was the most logical solution.

Construction on the Hogsback tunnel began in early 1875 by Elliot & Muir, and it only took a few months to bore. The result was a 127-foot-long tunnel through a relatively low point in the rock. For four years, the tunnel functioned adequately for the small locomotives and narrow-gauge trains that used it. But when the South Pacific Coast Railroad leased the line in 1879, surveyors concluded that the tunnel was too narrow and low to support its larger trains.

In July 1879, crews completely rebuilt the tunnel inside and out. They shifted the bore slightly to reduce the curve and lowered the bottom of the tunnel sufficiently to allow trains of appropriate heights to pass through. The end result was a tunnel over twice as long—282 feet—and troublingly spacious in the middle. It opened to through traffic in November 1879 as Tunnel 7.

The cut through the Hogsback, 2012. [Derek R. Whaley]
The fate of the tunnel, however, was sealed from almost the beginning. The ceiling was never far from the top of the Hogsback and the extra space inside added by the South Pacific Coast Railroad made it prone to debris frequently falling from the roof. This made it abundantly clear to the railroad that the solid granite had lost much of its initial integrity. In 1898, a work crew was preparing the tunnel for further widening in anticipation of the standard-gauging of the now-Southern Pacific line. Their probing prompted a complete collapse of the top of the tunnel. The only solution was to daylight the tunnel—the first of two tunnels to be daylighted along the route between San José and Santa Cruz. It was dismantled and the sides cut back enough to protect the tracks from further rockfalls and allow for standard-gauge trains to pass. Soon, all evidence of the tunnel was erased.

Geo-Coordinates & Access Rights:
Western Portal: Approx. 37.0112N, 122.0497W
Eastern Portal: Approx. 37.0105N, 122.0493W

Today, there is little to differentiate the location of this tunnel from the surrounding right-of-way except a substantial cut through the Hogsback. Trespassing is not advised as the route is owned by Roaring Camp Railroads and remains an active line, especially during summer months. It is also a narrow-cut so there is no place to easily escape an approaching train. The location serves as the boundary between Henry Cowell Redwoods State Park and Paradise Park Masonic Resort.

Citations & Credits:
  • Hamman, Rick. California Central Coast Railways. Second edition. Santa Cruz, CA: Otter B Books, 2007.
  • MacGregor, Bruce. The Birth of California Narrow-Gauge. Berkeley, CA: University of California Press, 2003.
  • Whaley, Derek R. Santa Cruz Trains: Railroads of the Santa Cruz Mountains. Santa Cruz, CA, 2015.

4 comments:

  1. I enjoy learning something new. Thanks!

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  2. I'm not saying there is gold on the outside washout gravel bar of the hogsback curve, but if I were a prospector (which I am) it's where I'd look for it ;) ;)

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  3. I was a Felton Firefighter when the “Tunnel Fire” occurred, in the 90’s I believe, went into the burning tunnel in a futile effort to stop the blaze. When the tunnel start4d collapsing, we retreated. Does anyone know what the name and number of that tunnel was? It was rebuilt as a cut as well.

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    1. Very cool! You're thinking of the tunnel about a mile to the north, which was numbered (in its later years) Tunnel #5. This website names it Tunnel #6 since that was its original designation by the South Pacific Coast Railroad. The area adjacent to the tunnel was originally known as Coon Gulch, although Roaring Camp does not use that name. Regardless, this website names it the Coon Gulch Tunnel accordingly. Technically, the former tunnel wasn't daylighted (turned into a cut), but rather a new route (or rather very old route from Santa Cruz & Felton Railroad days) bypassed the tunnel entirely by going through what was once called the Butte Cut. You can find out more about the tunnel here: https://www.santacruztrains.com/2019/11/tunnels-coon-gulch-tunnel-6.html.

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