Mosquito Bridge Project Overview

Project Overview
The Transportation Division of the El Dorado County Community Development Agency is beginning the process of looking into various alternatives to replace the existing Mosquito Road Bridge. The County will be updating the Mosquito Road Bridge Replacement Study that was completed in 1993. The 2013 Study Update will reassess the five bridge replacement alternatives evaluated in the 1993 Study. It will also identify any new/superior alternatives and include recommendations for the preferred alternative.

Highway Bridge Program (HBP) Funding
The Mosquito Road Bridge is eligible for federal funding under the HBP Off Federal Aid System 100% Reimbursement Program. In April 2011, the County received federal authorization to complete the planning and environmental phase and scope the project.

Current Bridge Conditions
The current bridge is a 9-foot wide, one-lane limited capacity timber suspension bridge with a 140-foot long span over the South Fork of the American River. The existing bridge was built in 1939 and is 74 years old. The bridge is crossed daily by approximately 1,300 vehicles (in both directions). Emergency vehicles are restricted from using the existing bridge due to the narrow bridge width, multiple hairpin curves and steep grades, resulting in delayed emergency response time.

Mosquito Bridge Maintenance
Annual routine maintenance is performed by the County’s bridge maintenance crew and costs an average of $45,000. The bridge is closed during this maintenance for approximately two weeks from 8 am to 3 pm, Monday through Friday, but is open nights and weekends. Extensive rehabilitation work is done when warranted per Caltrans inspection reports. The last major rehab was completed in 2010 and took two to three months. The 2010 rehab project cost about $367,000. During those months, the bridge was closed and all through traffic was rerouted to Rock Creek Road.

Existing Caltrans Sufficiency Issues
The bridge is routinely inspected by Caltrans every two years and is given a Sufficiency Rating (SR) from 0 to 100 based on 140 elements. If the SR is less than 80, the bridge is eligible for rehabilitation. If it is less than 50, the bridge is eligible for replacement. In 2006, Caltrans reported an SR of 0.00. In 2011, the SR was 12.5 (after the major rehabilitation work in 2010). The Mosquito Road Bridge meets federal criteria for replacement because it is classified as structurally deficient and functionally obsolete, has high daily use, and lacks standard barriers and railings.

Environmental Review
After the draft study update is completed, the consultant will begin the environmental analysis. The planning/environmental phase is a two to three year process. The anticipated project schedule is:
Planning/Environmental 2013-15
Preliminary Engineering/Design 2015-16
Right of Way/Permitting 2017
Construction 2018-19
Project Completion 2020

Public Input during Planning Process
Opportunities for public input on the alternatives considered, evaluation criteria, and the draft study update will be provided throughout the planning process.

Fact Sheet