Railroad Gazette/Volume 38/Number 5/New Tunnel
New Tunnel on the North Shore Railroad.
The North Shore Railroad, operating between San Francisco and Cazadero, Cal., has a main line 87 miles long, which passes through one of the most picturesque portions of the Coast Range Mountains. The main division is narrow gage, while the suburban division, also formerly a narrow-gage line, which runs from Sausalito to San Anselmo and San Rafael, was opened as a third-rail
Route of North Shore Railroad.
electric line on Sept. 15, 1903. This portion of the road connects San Rafael, Mill Valley and Mount Tamalpais with San Francisco, as the company operates its own ferries between Sausalito and San Francisco, a distance of six miles. The main line, narrow-gage trains, which are operated by steam, also run into Sausalito, using the same right of way as the electric trains from Sausalito to San Anselmo, a distance of 10 miles. Between Sausalito and San Anselmo is the Corte Madera tunnel 2,200 ft. long, which is lighted by electric lights placed at short intervals on the sides.
The narrow gage line from Sausalito to Cazadero encounters some heavy grades among the hills of Marin and Sonoma counties. The heaviest one is at White’s Hill, about 20 miles north of San Francisco, where a 2½ per cent. grade is encountered, running for a distance of about two miles. To push trains over this grade, it was necessary to employ double-headers, and sometimes a rear-end helper besides. Owing to the rapidly increasing traffic of the railroad, about two years ago, the North Shore management decided to do away with this grade, and work on a tunnel under White’s Hill was begun in April, 1903. The contract was originally given to Martin & Hinkle, who subsequently, in February, 1904, threw up the contract, alleging a steady loss. The work was then taken up by the railroad company’s own forces, and rapid progress was made so that the line was finally opened for traffic on Dec. 4, 1904. The length of the tunnel is 3,190 ft., or about three-quarters of a mile. It is standard gage, 17 ft. wide and 20 ft. high, and is thus ready to meet future requirements when the road is changed to a standard-gage line. The tunnel is built on a tangent and is timbered with 10-in. × 14-in. beams. It saves two miles in distance, 28 deg. of curvature and 104 ft. of vertical grade, as compared with the old route over
North Approach, White’s Hill Tunnel.
South Approach to the Tunnel.
White’s Hill. The percentage of grade, however, remains unchanged. The engineer’s report says that the tunnel was driven chiefly through a quartzite strata. The approximate cost of the entire work was $175,000. The running time of trains has been reduced about 30 minutes to points north of the tunnel, and the distance between San Francisco and Cadazero has been cut from 87 miles to 85 miles.
We are indebted to B. H. Fisher, Chief Engineer, and to J. L. Frazier, General Manager, for the data furnished and the photographs shown.