Sonoma County Quarterly Caltrans Update

Sonoma County Quarterly Newsletter header.

Widening Work Begins of the Hearn Avenue Overpass Project

Building a new Hearn Avenue Overcrossing while accommodating traffic on the existing overcrossing is no mean feat, and entails modifying traffic routes to allow construction work to happen. Caltrans has closed two turn pockets on the northwest side of the project to create space to build the first phase of the new overcrossing.

Caltrans has begun pile driving at the northwest corner of the project near the DMV, preparing for building the new wider overcrossing.

LINKS:

Visit our project website for additional updates.

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701 Culverts Drain Hwy 1 between Jenner and Gualala, Keeping Road Open During Wet Winters

Keeping traffic lanes viable on Highway 1 on the northern Sonoma coast may seem like an open-ended commitment that requires appraisal and reappraisal at the beginning and end of every wet season.

A culvert can be seen on the hillside along State Route 1 in Sonoma County.

A new culvert being installed on Hwy 1 in northern Sonoma County augmenting the smaller culverts that drain the slope

Prodigious winter rainstorms create runoff, which can cause mud and rockslides to tumble onto the road. Perhaps a more significant problem is water seeping into the soil and running underground, eroding the highway from below. The road's underpinning would be in constant jeopardy if it weren't for the many culverts crossing beneath the highway.

A culvert is a structure that carries water beneath a road to prevent erosion. In most cases, culverts are metal drainpipes of varying sizes. But sometimes, culverts can be concrete, primarily where creeks are channeled beneath a highway.

State Route 1 travels along a grassy hillside in Sonoma County.

Two things we know about water are that it travels downhill and seeks the path of least resistance. Hydrologists use that knowledge to analyze topography, finding the natural course of subsurface water.

Eventually, workers install a pipe, pointed downhill in a location where it—and perhaps its feeder pipes—will gather the most water and expedite it downslope where it won't harm the road. In the case of Highway 1, that place is usually the Pacific Ocean.

Caltrans engineers and maintenance workers can think of many better places to build a road than Highway 1 along the Sonoma Coast. A flat, dry field might be easiest. But such a place lacks the beauty and vitality of the coast, a place where people want to live, work, and vacation.

A culvert pip emerges from a retaining wall along State Route 1 in Sonoma County. 

The Caltrans Maintenance and Hydrology Departments have created a database of state highway culverts. The list is impressive but not exhaustive, as much of the road was inherited from local agencies that built it in the early-to-mid 20th Century. Not all culverts can be found on plans but must be located in the field. For example, on Highway 1 between Jenner and the Mendocino County line, Caltrans has compiled a list of 701 culverts.

It's a lot to maintain, which is why Caltrans created the database, which color-codes existing culverts according to their service level: blue, green, and red for excellent, good, and needs repair

With better data, Caltrans has made a list of worn and worn-out culverts and uses the list to develop repair projects that prioritize locations in greatest need of repair.

The database required extensive research and time to produce. But it was time well spent. Now more decisions can be made in the office, reducing the capital outlay and time-consuming fieldwork.

While culverts will inevitably deteriorate due to rust, blockages, or the relentless movement of the coast side earth, the availability of information at our fingertips now allows us to make significant progress in maintaining Highway 1.

Winter Recess on Route 116/121 Roundabout

An overhead rendering of the new roundabout that recently began construction at the intersection of State Route 116 and State Route 121 in Sonoma County.In early November, Caltrans will pause work on the Route 116/121 Roundabout Project southeast of Sonoma.

Before closing for the winter, however, Caltrans will reopen the bypass lane connecting northbound 116 to eastbound 121.Construction will begin again in March.

Sidewalk Upgrade Project on Route 116 in Guerneville

Project includes landscaping courtesy of Caltrans/Sonoma County Partnership

On September 4, 2024, Caltrans began a project to upgrade sidewalks, replace traffic signals, and add pedestrian beacons on State Route 116 in Guerneville between River Road and 4th Street, essentially the length of downtown Guerneville.

The improvements include replacing 23 curb ramps with ramps compliant with the Americans with Disabilities Act of 1990 (ADA).

Cars are parked in front of shops on State Route 116 in Guerneville.Traffic signals at River Road and Highway 116 will be replaced. The sidewalk between River Road and Armstrong Woods Road will be widened at each light pole to provide a 48-inch clearance. Driveways will be reconstructed to conform with the new sidewalks.

To enhance pedestrian safety, Caltrans will install pedestrian hybrid beacons and curb extensions at the intersections of SR-116 at Church and Mill streets. The new pedestrian signals will be High-Intensity Activated Cross-Walk beacons (HAWK), which will alert motorists to the presence of pedestrians.

Also, curb extensions will be installed at several locations to slow traffic and reduce the distance pedestrians must travel to cross the street. Caltrans and Sonoma County worked together to make other functional and visual improvements to the area, including adding 14 bike racks, 64 sidewalk sleeves for flags, and nine new tree wells.

Rendering of the the Fife Creek Bridge showing the widened sidewalk, new bridge rails, and ledger stone motif that will be added.

The Sonoma County newsletter will be distributed on a quarterly schedule.

Caltrans bay area logoFor 24/7 traffic updates, please visit 511.org or https://twitter.com/511SFBay
For real-time information, please visit Caltrans QuickMap:  https://quickmap.dot.ca.gov

CONTACT:

Sonoma County Public Information Officer
Jeff Weiss

General Information
(510) 286-4444

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