Trees along the edge of Highway 147 at Hamilton Branch Creek are removed so the roadway to the wider bridge can be built up. Photo by Susan Cort Johnson

Work on Highway 147 bridge begins


While the State Route 147 road closure adds a few extra miles for Westwood and Clear Creek residents driving to the peninsula, Hamilton Branch or the east shore of Lake Almanor, the long way around is working for their benefit.

As a result of the road closure the construction of a new bridge west of Clear Creek over Hamilton Branch Creek will take a fraction of the time it takes when traffic is monitored through the worksite.

“A bridge replacement like this will typically take two years to complete. Due to the closure of Highway 147 the work can be completed much faster with the goal of having a smaller overall impact to the local community,” said Ryan Johnson, resident engineer for Caltrans, Chico Construction Field Office.

According to James Ralston, a Caltrans structure representative, without the road closure half the bridge would be built at a time so traffic could pass through. Closing the road not only reduces the amount of construction time but cost as well.

There are many reasons for the construction project. The existing four-span steel girder bridge that is being replaced was built in 1948. As a result, the width does not meet current safety standards and its structure is not up to current seismic design standards. Ralston said the bridge will be almost double the current width.

According to Johnson, the new bridge will have 10 feet wide shoulders and seethrough steel barriers that will be taller for bicyclist safety.

In an email to the Westwood PinePress, Johnson wrote, “The existing bridge has history of concrete deck issues dating back more than 30 years including transverse cracking, spalling, and delamination. The concrete bridge rail exhibits damage from freeze/thaw deterioration and abrasion from snowplow activities. The existing coating system is deteriorating and rusting throughout the bridge.”

A Caltrans Structure Maintenance and Investigation review was conducted in 2009 to determine rehabilitation strategies. An advanced planning study determined a full bridge replacement would be the most cost effective.

Replacement of older bridges is a common practice in California, said Johnson. Bridges are inspected once every two years as part of Caltrans Structures Maintenance and Investigation. Bridge engineers review the inspection reports and schedule the repairs and maintenance. If rehabilitating the bridge is too costly, it is replaced. Viking Construction, based in Rancho Cordova,