History: Rainbow Bridge: Beauty in the mountains
Special to the Sierra Sun
Rainbow Bridge is a famous structure on Donner Summit that is one of the wonders of California. It has been used in commercials (especially car ads), been the subject of countless pictures by tourists and commercial and art photographers, and it’s been used as a prop in movies like “True Lies.”
Before Rainbow Bridge was built the old Lincoln or ‘Victory’ Highway wound steeply down Donner Summit with grades as high as 18%. With the 1920s automobiles became a popular mode of transportation. They had improved mechanically and people began vacationing with their cars sometimes pulling trailers. Trucks had also improved and become a common form of long haul transportation of goods. More vehicles were using Lincoln Highway as well so people were thinking about improvement of the road.
In the Lake Tahoe area, lumber had been moved by railroads but as increasing demand for lumber could not be met by the Truckee lumber mills, trucks began hauling logs to mills elsewhere. The only route was up over Donner Summit on the Lincoln Highway with its high grades.
Since autos and trucks were being used more, it became necessary to improve the roads. In 1923 the State began the construction of “a wide, modern highway with easy grades and good alignment.” By 1924 the road had been completed to about a half mile east of Donner Summit. The route over the top still needed to be completed but that sat on U.S. Forest Service land. So, the U.S. Forest Service stepped in. Not only did the Forest Service own the land but they needed to facilitate the transportation of lumber out of the Truckee basin to distant mills. So the final 3.7 miles of road, including a bridge, were built “by the United States Bureau of Public Roads with Forest Service highway funds” which took the new modern highway to Soda Springs.
Rainbow Bridge is unique because of its engineering. It’s built on a compound curve with grade. That had never been done before. For engineers, the final construction report of 1925 says, “The alignment consists of a series of compound curves; there being a 360 foot radius curve over the arch and a 145 foot radius over each approaching span.” Its arch is 110 feet long with a depth of 70 feet. The road is 241 feet long and 24 feet wide.
The gravel and sand that made up the concrete for the bridge was mined at Donner Lake and taken up the old road to the top. There it was taken down to the bridge construction site for mixing. Bridge construction progressed from the west to east which was the downhill direction. That made moving freshly mixed concrete in wheelbarrows easier!
The bridge and final parts of the highway were finished in 1926 for $450,000. The bridge itself was estimated at the onset at $26,000. The final bridge cost $37,304.32 partly due to design changes and additions. The final cost gave the contractor a profit of about $1,319. At the dedication in 1926, C.F. McGlashan gave a talk and descendants of the Donner Party were present. A commemorative, heavy bronze plaque was placed which dedicated the bridge “To the Pioneers who blazed the Overland Trail through these mountains.” The plaque depicts wagon trains, gold miners, Donner Lake and other scenes from summit history.
The plaque was stolen from the bridge and was later “discovered.” A duplicate was made to protect the original and that duplicate was installed on the bridge. The Truckee-Donner Historical Society ended up with the original and generously loaned it to the Donner Summit Historical Society for display. It now hangs inside the front door at the Donner Summit Historical Society museum.
Rainbow Bridge eliminated the terrors of the Donner grade and was a great improvement not just in the summer but also later and earlier in the season allowing the road to be open many more weeks in the year.
Bill Oudegeest has had a house on Donner Summit for more than forty years. He is a retired public school teacher and administrator and one of the founders of the Donner Summit Historical Society. He writes and edits the Donner Summit Heirloom, has published two books on local history, written a variety of pamphlets and exhibits, leads hikes, and more. Judy DePuy is a member of the Truckee-Donner Historical Society and Donner Summit Historical Society. She is on the board for the Museum of Truckee History and Truckee Donner Railroad Society. Judy is passionate about our history and resides in Tahoe Donner
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