09 November 2022
Designed by SYSTRA International Bridge Technologies, this new road crossing will eventually replace a wooden suspension bridge dating from 1939.
Le futur pont (vue d'artiste) / The future bridge (artist view)

In California, the company Shimmick Construction laid the first stone of the new Mosquito Road Bridge, designed by SYSTRA IBT in partnership with Quincy Engineering Inc. Together, our teams carried out the preliminary studies and final design of this new structure which will overlook South Arm of the American River, for our client El Dorado County.

The ‘Swinging Bridge’ will become a footbridge.

A record work on the road to the gold rush

The construction of this new bridge resonates with the history of the United States: the American River is indeed the river where the gold rush began in 1848, with the discovery of the first nuggets at Sutter’s mill.

In the midst of gold fever, California acquired its first single-lane wooden bridge in 1867, replaced identically in 1939. This local landmark is however in poor condition: often under maintenance, nicknamed “Swinging Bridge”, it is known to be a dangerous traffic axis in the region, with a maximum weight limit per vehicle of 5 tons.

The future bridge seen from the bottom of the American River valley.

El Dorado County had therefore chosen SYSTRA to design a new structure, while retaining the historic wooden bridge, which will be limited to pedestrian and cyclist crossings. The Mosquito Road Bridge deck will culminate at 114 meters in height, and the maximum span between its piers will be 163.4m.

The structure chosen is that of a cantilever bridge, which will be made of a post-tensioned concrete box-girder with elements cast on site. SYSTRA IBT was more specifically responsible for the calculations for the preliminary studies, the final design of the superstructure and the columns, and the review of the studies for the foundations and the abutments.

When completed, by 2025, the Mosquito Road Bridge will provide a fast and direct connection for the surrounding communities to Sacramento and Lake Tahoe, through the California hinterland, via the town of Placerville in the Swansboro area.

Key features – Mosquito Road Bridge

  • Length: 365m
  • Maximum height of the deck: 114m
  • Number of piers: 2
  • Maximum span between stacks: 163.4m
  • Span of end spans: 98.2m
  • Maximum pier height: 61m

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