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State Route 121

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Routing Routing

  1. Rte 121 Seg 1From Route 37 near Sears Point to Route 29 near Napa.

    Post 1964 Signage History Post 1964 Signage History

    This segment is unchanged from its 1963 definition.

    Pre 1964 Signage History Pre 1964 Signage History

    Between the original signage of state routes in 1934 and 1964, this was part of Route 37. It was LRN 8, defined in 1909.

    Rte 12/37 Schelleville to Sonoma Freeway AdoptionIn 1961, there was controversy regarding a proposed freeway routing for Route 12 and Route 37 (today's Route 121) near Sonoma. The State Highway engineer recommended the Modified P Route. This route follows the existing highway from Sign Route 48 (now Route 37) to Sears Point, passes W of the Schellville Airport and runs to the junction of Sign Route 37 (now Route 121) and Route 12. That portion was not contested. What was contested was the next portion, which runs W of Sonoma from the site of A&B market, the N route, and the Sangiacomo Orchards parallel to Watmaugh Rd to Arnold Dr., where it would veer N  at an interchange and run between Arnold Dr. and existing Route 12 to a point E of Glen Ellen where it comes back to parallel the existing Route 12. There was a large amount of opposition to this route. The freeway routing was adopted. Later, in 1977, the CHC advertised for public comment regarding rescinding the adoption of Route 12 and Route 121 in this area, from Melita Road to the Sonoma/Napa County Line on Route 12, and from Sonoma to Sears Point on Route 121. The rescinding seems to have been approved, for as of 2023, the routing is still the original non-freeway routing through Sonoma.
    (Source: Press Democrat, 9/28/1961, via Joel Windmiller, 2/1/2023; Press Democrat, 2/3/1977 via Joel Windmiller, 2/23/2023)

    Status Status

    In March 2012, the CTC authorized SHOPP funding on Route 121 04-Son-121 3.4/6.5 Near Sonoma, within the San Francisco Bay Trail (PM 3.4/6.5 and PM 8.6/11.6) on Route 121. $350,000 to install centerline rumble strips to reduce the number of cross-centerline collisions and improve safety.

    Schellville Collision Reduction Project (04-Son-121, PM 3.36/6.50)

    In March 2019, the CTC approved for future consideration of funding a project located on Route 121 near the community of Schellville in Sonoma County (04-Son-121, PM 3.36/6.50). The project proposes to reduce the occurrences of cross-centerline and rear-end collisions on this portion of roadway. The proposed project will also widen shoulders, upgrade curves, add two way left turn lanes at various locations, and install rumble strips. The project proposes to address the higher than statewide average of cross centerline accidents and fatalities at this project location during a five-year period (Two and Three Lane Safety Monitoring Report). This project is fully funded and programmed in the 2018 SHOPP for approximately $43.5 million. Construction is estimated to begin in Fiscal Year 2019-20. The scope, as described for the preferred alternative, is consistent with the project scope programmed by the Commission in the 2018 SHOPP.
    (Source: March 2019 CTC Minutes, Agenda Item 2.2c.(1);March2019 CTC Minutes Agenda Item 2.1a.(1) Amendment Item 3)

    In January 2022, the CTC amended the SHOPP to delete this project: 04-Son-121 PM 3.4/6.5. PPNO 04-0738; ProjID 0400020007; EA 0G680. Route 121 Near Schellville, from north of Tolay Creek Bridge to south of Yellow Creek Bridge. Widen for standard shoulders, upgrade curves to standard, extend two-way left turn lane, and install rumble strips. Note: Delete project.  The collisions in the area have reduced as a result of rumble strips and High Friction Surface Treatment (HFST) installed under other projects.
    (Source: January 2022 CTC Agenda, Agenda Item 2.1a.(1d) #5)

    In June 2018, it was reported that Caltrans is holding community meetings to discuss a coming safety improvement project on Route 121 between Wagner and Bisso roads, south of the Bonneau Rd. intersection past Cornerstone and Viansa Winery. The project proposes to reduce accidents and improve safety by implementing safety measures, such as widening shoulders, realigning the roadway and adding a center-turn lane where necessary. The project is immediately south of the Bonneau intersection of Route 121 (Fremont Drive) and Route 116 (Arnold Drive) (~ SON 6.622) known as Big Bend. That intersection has been studied by the Sonoma County Transit Authority and Caltrans to install a hybrid multilane roundabout, currently in its final planning stages. The environmental document will be finalized in Fall 2018.
    (Source: Sonoma Index-Tribune, 5/28/2018)

    Route 116/Route 121 Roundabout (04-Sonoma-121 PM 6.5/7.0)

    Rte 116/Rte 121 RoundaboutIn December 2014, it was reported that the state is moving ahead with plans that call for a possible two-lane roundabout or traffic signal at the intersection of Route 116 and Route 121. Officials are still assessing environmental and other impacts, such as a noise, for both options before they can move ahead with designs. They’re also meeting with business and vineyard owners, who could see some encroachment if a roundabout is built. If approved, construction could start around 2019-2020. It’s taken so long to deal with the crossing at Route 116 and Route 121 in part because of the number of government agencies involved. The plans also call for sidewalks up to 10 feet wide, which would accommodate both pedestrians and bicyclists. An existing park-and-ride lot could be relocated and the nearby bridge over Yellow Creek replaced.
    (Source: Press-Democrat, 12/21/2014; Image source: Adapted from Sonoma County Gazette, 5/15/2020)

    The 2020 SHOPP, approved in May 2020, included the following NEW Mobily item of interest: 04-Sonoma-121 PM 6.5/7.0 PPNO 2031J Proj ID 0412000557 EA 3G900. Route 121 near Schellville, at the intersection of Routes 121 and 116. Construct roundabout. Programmed in FY22-23, with construction scheduled to start in March 2023. Total project cost is $18,869K, with $16,819K being capital (const and right of way) and $2,050K being support (engineering, environmental, etc.).
    (Source: 2020 Approved SHOPP a/o May 2020)

    In May 2020, it was reported that CTC approved the 2020 SHOPP, which included funding in the amount of $19M to complete improvements at the intersection of Route 116 and Route 121 southwest of the City of Sonoma. The money will become available in 2022. Measure M, the ¼-cent sales tax for transportation, was used to leverage the state dollars in order to fully fund the improvements. Measure M is contributing $5M. The project will improve traffic circulation and safety for all users and reduce congestion by removing the current stop sign-controlled intersection and installing a roundabout at the intersection of Highway 121 and 116. The project will also widen the roadway to allow for turn lanes into and out of existing commercial uses. The Park and Ride lot will be relocated; the parking capacity will remain the same in the new location. SCTA serves as the project sponsor and Caltrans will build the project. The current cost estimate for this project is $24 million, and construction is currently scheduled to start in early 2023. The environmental documentation for compliance with the National Environmental Protection Act / California Environmental Quality Act (NEPA/CEQA) and project approval was completed in April 2018. Design and right of way phases are underway and will be completed by 2022.
    (Source: Sonoma County Gazette, 5/15/2020)

    The roundabout is part three of a five-part Sonoma County Transportation Authority 'local streets' project to improve traffic conditions along Arnold Drive (Route 116, and continuation of the street N of the point Route 116 turns off onto Stage Gulch Road), funded by Measure M, the quarter-cent sales tax for transportation improvements passed by county voters in 2004. The first part of the Arnold Drive project was widening the two-lane road's shoulders just south of Glen Ellen (off the state highway system, near Route 12), which was completed in 2012. The second part was the Hap Arnold Roundabout at the intersection of Agua Caliente Road (off the state highway system), completed in 2014. Note that the SHOPP grant for this project won't become available until 2022, when Sonoma County Transportation Authority supplies the additional $5 million in sales tax revenues to reach the $24 million mark. The project approval and environmental review were finished in spring 2018, setting up design of the roundabout and negotiating for adjacent property by 2022, when the state funding will be available. Construction is expected to begin in early 2023 and completed by the end of 2024.
    (Source: Sonoma Index Tribune, 5/18/2020)

    Rte 12/121 interchangeIn 2012, the intersection of Route 12 and Route 121 (04-SON-121 PM 007.45) was reconfigured. Prior to 2012, the intersection had a number of angular junctions. After reconstruction, the intersection of Route 12 and Route 121 was a traditional T-interchange, with nearby Fremont road being turned into a westbound only spur. The changes were prompted by an higher-than-average accident rate at the intersection. The cost of the project is $2.4 million.

    Huichica Creek bridge project (04-NAP-121 0.5/1.0)

    Rte 121 Huichica BridgeIn November 2017, there was an update on the $13.9 million Huichica Creek bridge project (04-NAP-121 PM 0.75), which could begin construction in 2020 and last for two years. The stated goals are to make the highway safer for motorists and to make the creek easier to navigate for fish. Caltrans intends to demolish an old bridge, build a new one and still allow an average of 32,000 vehicles daily to keep crossing the creek under Route 121, which is also known as Route 12 and the Carneros Highway. The idea is to do the project in phases, with the new bridge overbuilt initially and the extra width removed during the last phase. Traffic will shift as a section of the new bridge is built and a section of the old bridge is removed. A new Huichica Creek bridge will be the final piece of a bigger project that improved virtually all of a 1.7-mile stretch from Duhig Road in Napa County to the Sonoma County line. Caltrans didn’t replace the Huichica Creek bridge along this stretch of Route 121 to fit in with the rest of the wider roadway. The reason was proposed fish passage improvements associated with the proposed bridge didn’t satisfy various state and federal environmental agencies. Huichica Creek flows for about 16 miles from the southern Mayacamas mountains to Napa Slough, which empties into the Napa River. Steelhead trout are in the stream. The state Department of Fish and Wildlife considers the portion of the creek at the bridge to be a fish barrier to upstream spawning grounds. Downstream of the bridge is a six-foot to eight-foot drop that fish have trouble passing. The creek crosses under the bridge in three 78-inch-wide metal culverts built in 1968, when environmental laws were laxer. The new-and-improved Huichica Creek bridge would have no culverts, but would be a free span bridge clear of the creek. Caltrans proposes to remove paved portions of the creek channel near the bridge, create a gentler slope in the channel and build eight step-pools that fish could travel between with a maximum half-foot jump. Fish passage improvements are to extend 300 feet downstream of the bridge and 130 feet upstream. The new bridge will even allow more light to penetrate to the bottom of the creek. That should allow for natural physical and biotic conditions.
    (Source: Napa Valley Register, 11/6/2017)

    The following project was included in the final adopted 2018 SHOPP in March 2018: PPNO 0775G. 04-Napa-121 0.5/1.0. Route 121 Near Napa, at Huichica Creek (PM 0.75). Roadway widening. Begin Con: 7/17/2020. Total Project Cost: $20,469K.

    In June 2018, the CTC approved for future consideration of funding the following project: 04-Nap-121, PM 0.5/1.0 Huichica Creek Bridge Replacement & Fish Passage Project: Replace existing bridge and make improvements to an existing fish passage on Route 121 in Napa County. (MND) (PPNO 0775G) (SHOPP). This project is located on Route 121 over Huichica Creek near the city of Napa in Napa County. The project proposes to widen Route 121 over Huichica Creek, remove existing culverts and replace with a free span bridge. The project also incorporate fish passage improvements along Huichica Creek. The proposed project will also reduce crosscenterline and run-off-the road accidents and restore creek banks along Huichica Creek. This proposed project is estimated to cost a total of $22.5 million. The project is funded for the first phase of this project and is currently programmed in the 2018 SHOPP for approximately $20.5 million which includes Construction (capital and support) and Right of Way (capital and support). The project is estimated to begin construction in 2020. The scope, as described for the preferred alternative, is consistent with the project scope programmed by the Commission in the 2018 SHOPP.
    (Source: CTC Agenda, June 2018 Agenda Item 2.2c(1))

    In October 2019, the CTC had on its agenda a supplemental funding request for an additional $1,200,000 in Capital Outlay Support (COS), for the Plans, Specifications and Estimate (PS&E) phase for the Huichica Creek Bridge (04-NAP-121 0.5/1.0, PPNO 0775G Proj ID 0412000310 EA 4G210). This project is located on Route 121 near the City of Napa, in Napa County. The project will construct a single-span bridge to replace the existing culvert at Huichica Creek Bridge. The project also includes the accommodation of fish passage as required by resource agencies. This bridge project is the second phase of a two-phase, two-mile roadway widening/curve correction and a roadway safety improvements project. The bridge work was separated from the roadway work to avoid delays and provide time to conduct environmental studies and address concerns regarding work in the creek and fish passage. The Department is requesting supplemental funds in the amount of $1,200,000 to complete the PS&E phase. This is because additional resources will be needed to address requirements for habitat restoration and fish passage mitigation from the California Department of Fish and Wildlife (CDFW) and National Marine Fisheries Service (NMFS). To secure the Incidental Take Permit (ITP) from CDFW and address concerns from NMFS, additional efforts are necessary to complete hydraulic and geomorphic analyses and develop a range of feasible design alternatives for fish passage. The Department must modify the original bridge and footing designs to accommodate the regrading of streambed slopes and minimize creek channel scour. Because of the presence of various species, including fairy shrimp, yellow legged frog and steelhead trout, it has been particularly challenging to arrive at a consensus design that meets current design and safety standards, protects and enhances environmental resources and addresses permit requirements.
    (Source: October 2019 CTC Agenda, Agenda Item 2.5e.(1))

    In January 2021, the CTC was informed of the following SHOPP Safety allocation under delegated authority: (3) #1. $15,196,000. 04-Nap-121 0.5/1.0. PPNO 04-0775G ProjID 0412000310 EA 4G210. Route 121 Near Napa, at Huichica Creek Bridge No. 21-0001 (PM 0.75).   Outcome/Output: Improve safety by widening roadway at Huichica Creek by replacing the existing triple metal culverts with a free span bridge, improve fish passage, and restore creek banks.  This project will provide continuity to the widening constructed under safety project EA 44420, and will reduce the number and severity of collisions. CON ENG $3,000,000; CONST $12,247,000.
    (Source: January 2021 CTC Agenda, Agenda Item 2.5f.(3) #1)

    Carneros Intersection (04-Nap-121 PM 04.47)

    Carneros InterchangeIn July 2017, a new proposal emerged for the Carneros Junction: Where Route 29 meets Route 12/Route 121 (04-Nap-121 PM 04.47). No massive interchange is proposed to replace traffic signals at the T-intersection for Napa and Sonoma flows. Instead, the three-year-old idea is to add merge lanes, give some lanes a constant green light and reap a little congestion relief. The NVTA took a close look at the Carneros intersection in its 2014 Highway 29 Gateway plan. This study concluded an interchange with on-ramps and off-ramps is the ultimate solution, but that such a structure would be costly and could have big environmental impacts. One alternative is building the Carneros interchange roundabout, either with or without traffic signals. This wouldn’t make a big congestion-easing difference in the long run, the plan concluded. That leaves the $1 million idea to ease congestion on the (relative) cheap. Northbound Route 29 traffic presently stops at a red light when Route 121 traffic coming from the Sonoma direction turns left toward Napa. The proposed change – have northbound traffic always flowing through the intersection. And what happens when the Highway 121 traffic makes a left turn in front of it? A long merge lane would be created so these divergent traffic streams have space to come together. The same concept would be used so southbound Route 29 traffic turning right onto Route 121 toward Sonoma could always have a green light. A long merge lane would be the buffer when northbound Route 29 traffic makes a left turn onto Route 121. This proposed project wouldn’t necessarily make Carneros intersection a motorist’s paradise. There would still be a red light during the southbound Route 29 morning commutes. The bigger, more expensive project for the more congested Soscol Junction a few miles south along Route 29 remains the NVTA’s priority. The agency and Caltrans are working on that project’s environmental impact report. Still, the smaller Carneros intersection project is at least in the agency’s sights, even if there is no timeline to build it and no state-required environmental report has yet been launched. If all had gone as planned in the 1970s, both the Carneros and Soscol Junction intersections would already be interchanges today. Caltrans during that decade was figuring out the huge Southern Crossing project. Route 29 at that point went north on Route 221 and then cut across the valley on Imola Avenue. Route 29 then continued north up Napa Valley and Route 121 went west to Sonoma. All of that led to congestion near Napa State Hospital and on Imola Avenue. Caltrans and county officials wanted a Southern Crossing bridge – today’s Butler Bridge – so Route 29 could bypass the city of Napa several miles to the south. The Southern Crossing project approved in 1974 included interchanges at both entrances. But in 1975, state transportation officials pleaded poverty and proposed installing traffic signals instead. The state would return to build interchanges “when traffic warrants them.” By 1977, the state didn’t even have money to connect Route 29 to the bridge it was already building over the Napa River. County officials went from worrying about having interchanges to keeping the Southern Crossing from becoming a bridge to nowhere. In 1981, the state finally opened the several miles of connecting highway that made the Butler Bridge part of Route 29. But the interchanges had dropped from the plans, replaced by the traffic signals.
    (Source: Napa Valley Register, 7/15/2017)

    Naming Naming

    Route 121 from Route 37 to Route 29 in Sonoma and Napa Counties is named the "Carneros Highway". The road is named for the wine-growing region south of the Napa Valley. Carneros refers to the area's cattle ranching history. Named by Senate Concurrent Resolution 62, Chapter 29 in 1992. Note that route is called "Arnold Drive" between Route 116 and Route 37, at least as far as residents and the post office is concerned.

    The portion of this route running through Sonoma County is called the "Valley of the Moon Scenic Route". "Valley of the Moon" was the name Jack London, resident of Glen Ellen, coined for this area.

    Historically, this route is close to the original "El Camino Real" (The Kings Road). A portion of this route has officially been designated as part of "El Camino Real by Assembly Bill 1707, Chapter 739, on October 11, 2001.

    Scenic Route Scenic Route

    [SHC 263.6] From Route 37 near Sears Point to Route 12 near Sonoma; and from Route 221 near Napa State Hospital to near the vicinity of Trancas Street in northeast Napa.

  2. Rte 121 Seg 2From Route 29 in Napa to Route 128.

    Post 1964 Signage History Post 1964 Signage History

    In 1963, this segment was defined as "(b) Route 29 near Napa State Hospital to Route 128."

    In 1984, Chapter 409 changed the definition to originate as "Route 29 in Napa" The portion from Route 29 in Napa to Route 29 [now Route 221] near Napa State Hospital was transferred from Route 29. This was a side effect of the opening of the new Route 29 freeway. This bypassed the older segment of Route 29 than ran from Suscol Ave N to Imola (State Hospital), and then along Imola to Solano Avenue. The bypassed segment was split between Route 221 (Route 29 to Imola, the number coming from a deleted bypass N of Napa) and Route 121 (State Hospital along Imola to Solano (Route 29)).

    Pre 1964 Signage History Pre 1964 Signage History

    Between the original signage of state routes in 1934 and 1964, this was signed as part of Route 37. It was part of the 1933 extension of LRN 6.

    Status Status

    Imola Corridor PlanIn August 2020, it was reported that the Napa Valley Transportation Authority (NVTA) has just released the draft Imola Corridor Complete Streets Improvement Plan, with a goal of creating a better Imola Avenue through Napa (~NAP R4.533 to NAP R5.883). Once the vision is finalized, transportation officials will seek money to make it a reality. The 3.5-mile-long street, a section of which is Route 121, is a hodgepodge of eras, looks and neighborhoods. Some parts have sidewalks, others don’t. One section passes homes, another bustling shopping centers, another vineyards, another the oak-covered hills of Skyline Wilderness Park. The goal is to transform car-centric Imola Avenue into a road that also emphasizes walking, cycling and mass transit. Estimated cost is $14.3 million. Among the proposed pedestrian improvements is adding curb extensions at busy intersections to lessen crossing distance. Sidewalk gaps would be filled in. Eye-catching crosswalks with multiple pavement lines would be added. A system of bike routes, protected bikeways and multi-use paths would go in. One feature is creating “transit islands” for bus stops where buses stop in the travel lane. These concrete islands for those boarding buses allow the on-street bike lane to pass behind the bus stop, eliminating potential conflicts between buses and cyclists. There is a variety of potential funding sources, from the state Active Transportation Program to the local Measure T sales tax to traffic impact fees to environmental mitigation. Funding would be on a sub-project by sub-project basis.  The draft plan includes a benefit-cost analysis. This analysis seeks to put a money value on such things as pedestrian and cyclist accidents avoided because of the safer street and air pollution avoided because more people ride bikes. Total benefits over 20 years would be $83 million, using Caltrans benefit-cost methods. That compares to $14.3 million to build the projects and another $2 million to maintain them over 20 years. The benefit–cost value is 5.15:1. Not all of three Imola Road segments are equal, though. The west segment from Foster Road to Jefferson Street has benefit-cost ratio of almost 13.9-to-one; the Jefferson Street-to-Soscol Avenue segment 2.76-to-one and the Soscol Avenue-to-Fourth Avenue segment 1.82-to-one. Caltrans noted that the agency is planning in 2024 to start repaving Route 121 from Route 29 to Vichy Avenue near Silverado Trail. The cost is to be $32 million. Of those more than five miles, about 1.3 miles is along Imola Avenue. Go to to see the draft Imola Avenue Corridor plan.
    (Source: Napa Valley Register, 10/5/2020; Image source: Imola Corridor Plan)

    In 2004, a new bridge was constructed in South Napa over the Napa River. Called the "Imola Avenue Bridge" (evidently, bridge 21-0108, 04-NAP-121 PM R005.30), it will replace the "Maxwell Bridge" and was the site of a collapse in November 2003 that killed four and injured four. The Maxwell Bridge, built in 1949, was adequate in its day, but now it's a major bottleneck for highway and river traffic and flood water. Four lanes of Imola Avenue traffic are funneled into two lanes at the bridge. Big boats have to give 72-hour notice so Caltrans can raise it. Pedestrians and bicyclists are herded onto a narrow outrigger on the north side only. By 2005, there will be a $40 million replacement bridge allowing for four lanes for motorists. There will be eight-foot lanes in each direction for bicyclists and pedestrians. Boats will have a 60-foot clearance. And the Napa Valley Wine Train will go under the eastern approach, not through it. The design is as an elevated skyway, with a smooth, long arch over the river, with more lighting and pedestrian-bicyclist facilities. Although a Caltrans bridge, the project was put together by the city of Napa working under a tight deadline so as to not delay the Napa River Flood Control Project. Half of the new span will begin construction this month about 100 feet north of the Maxwell Bridge. By October 2004, traffic will be shifted onto the two new lanes, the old bridge will be torn down and the final two lanes built. Because the new span will be 1,700 feet long, rising 60 feet over the river, it will eliminate a bottleneck that traps flood water. The deck of the new bridge will be about as high as the bottom of the concrete counterweights on the present bridge. Bridge Pictures.
    (Source: Napa Valley Register, 4/12/2003)

    The 2020 SHOPP, approved in May 2020, included the following NEW Bridge Preservation item of interest: 04-Napa-121 PM 6.4/6.5 PPNO 1493C Proj ID 0416000041 EA 4J820. Route 121 in the city of Napa, at Tulocay Creek Bridge No. 21-0003 (PM 6.423). Replace existing bridge with a single span precast concrete box girder bridge. Programmed in FY23-24, with construction scheduled to start in February 2025. Total project cost is $32,972K, with $21,862K being capital (const and right of way) and $11,110K being support (engineering, environmental, etc.).
    (Source: 2020 Approved SHOPP a/o May 2020)

    The 2020 SHOPP, approved in May 2020, included the following NEW Mobility item of interest: 04-Napa-121 PM 7.2/7.4 PPNO 1483B Proj ID 0414000097 EA 0J890. Route 121 in the city of Napa, at the intersection with Third Street/East Avenue/Coombsville Road. Construct intersection improvements. Programmed in FY23-24, with construction scheduled to start in February 2025. Total project cost is $3,900K, with $2,300K being capital (const and right of way) and $1,600K being support (engineering, environmental, etc.).
    (Source: 2020 Approved SHOPP a/o May 2020)

    Silverado Trail, 5-Way Intersection Improv (PPNO 0380N) (near 04-NAP-121 PM 9.047)

    Napa RoundaboutsIn February 2017, it was reported that years of discussions about untying the five-way intersection at Silverado Trail, Third Street, East Avenue and Coombsville Road (near 04-NAP-121 PM 9.047) have been boiled down to a twin-roundabout plan just approved by the Napa City Council. The pair of circular hubs is meant to keep drivers moving in any direction, without the sharp turning angles and long waits at the existing stoplight, while also improving safety for those on bicycle or foot. The roundabouts were one of 13 proposed redesigns that were scrutinized over the past three years by city engineers, state transportation officials, and citizens who attended idea-gathering forums on modernizing the five-way junction. Public works staff gave their backing to a design that channels traffic into a four-way roundabout connecting Silverado, East and Third to the north, and a three-leg southern hub linking Silverado with Coombsville. That plan would require fewer land takings than another two-roundabout design hooking Silverado, Third and Coombsville into the south hub, which would have forced an expensive realignment of Third Street, according to John Ferons, senior civil engineer. City engineers rejected a single circle connecting all five routes, as well as a design that would have consumed less land but restricted East Avenue to right-turn entry and exit only. Napa’s choice of a double roundabout will form the heart of a document it needs for Caltrans to approve, design and complete the project. Caltrans is the project’s final authority because Silverado Trail carries a section of state Route 121. Napa and Caltrans, which oversees the part of Silverado carrying state Route 121, are scheduled to draw up a project study, environmental documents, plans and a final cost estimate by the fall of 2021. Land acquisition is expected to continue to the end of that year, with construction planned from June 2022 to October 2024.
    (Source: Napa Valley Register, 2/8/2017)

    The 2018 STIP, approved at the CTC March 2018 meeting, appears to allocate $1.153M in FY21-22 for R/W acquisition for this project. The City of Napa has a page on the project, which notes:  City staff conducted public outreach meetings, evaluated multiple alternatives and developed the design concepts analyzed in a Caltrans Project Study Report – Project Initiation Document (PID). The Draft PID document was presented to City Council for their consideration and recommendation of an alternative at the scheduled City Council meeting on February 7, 2017. Following the City Council meeting, Public Works staff delivered the Draft PID document to Caltrans. Caltrans will finalize the document and begin the design process. The PID document also provides the information necessary to make the project competitive for federal, state, and regional funding. The recommended alternative is a double-roundabout configuration with a 4-leg roundabout to the north to serve Third Street, Silverado Trail and East Avenue and a 3-leg roundabout to the south to serve Silverado Trail and Coombsville Road. This alternative design, known as “Option 5F” provides traffic access for all street approaches of the intersection. A single, larger hub hooking into all five streets would have required difficult excavation into the hillside where East Avenue and Coombsville Road converge. Meanwhile, another dual-roundabout plan joining the Trail with Third and Coombsville at its south hub would have boosted the cost to $12.7 million, and forced a realignment of Third Street that would have removed a commercial building that houses Pearson’s Appliance & TV and other businesses.

    In March 2020, the CTC approved the 2020 STIP, which moved the programmed funding of $1,153K for PPNO 0380N "Rt 121/Silverado Trail, 5-Way intersection improv (SHOPP)" from FY 21-22 to FY23-24.
    (Source: March 2020 CTC Agenda, Item 4.7, 2020 STIP Adopted 3/25/2020)

    Sarco Creek Bridge (04-NAP-121 PM 009.30)

    In June 2016, the CTC approved for future consideration of funding a project in Napa County that will replace the existing Sarco Creek bridge on Route 121 near the city of Napa (04-NAP-121 PM 009.30). The project is programmed in the 2014 State Highway Operation and Protection Program. The total programmed amount is $19,077,000 for capital and support. Construction is estimated to begin in Fiscal Year 2016-17. The scope, as described for the preferred alternative, is consistent with the project scope programmed by the Commission in the 2014 State Highway Operation and Protection Program.

    In June 2016, the CTC approved $5,419,000 for a project in Napa County near Napa, at Sarco Creek Bridge No. 21-0008 and Silverado Trail Road. Outcome/Output: Replace bridge to address scour critical issues, include standard shoulders on new bridge, make improvements to facilitate fish passage, and increase stream bed capacity to meet 100 year storm event needs. Concurrent Consideration of Funding under Resolution E-16-35; June 2016

    In June 2019, it was reported that the Milliken Creek Bridge is again intact, having recovered from a car wreck and an earthquake. Stephen Simich put the finishing touch on the comeback for the historic bridge while also honoring a pioneer-era founder of his own Napa Marble & Granite Works. Simich restored the stone dedication plaque for the 1908 stone arch bridge at Trancas Street and Silverado Trail near the city of Napa (near 121 NAP 9.431). The plaque had been dashed into pieces by the August 2014 South Napa earthquake. The name of the bridge builder is commemorated on the plaque – H.W. Wing. Wing and fellow stone mason James Newman in 1878 founded Napa Marble & Granite Works. The Simich family has operated the business located at Third Street and Coombsville Road since 1946. The Milliken Creek Bridge has taken hard knocks in recent years. In May 2014, a chain-reaction accident caused by a suspected drunk driver shattered much of the bridge railing. Then the earthquake hit in August 2014, dislodging and breaking the stone plaque. Napa County reopened the bridge in September 2014 after putting temporary bracing and concrete railing in place. Milliken Creek Bridge is one of Napa County’s prized stone arch bridges from the late 1800s and early 1900s. The county has about 27 public masonry arch bridges remaining that are 20 feet long or longer, according to Caltrans. Milliken Creek Bridge is on the National Register of Historic Places.
    (Source: Napa Valley Register, 6/25/2019)

    In May 2016, it was reported that Route 121 is at least several months and $5.5 million away from once again having both lanes open north of Wooden Valley Road between Napa and Lake Berryessa (near 04-NAP-121 PM 16.039). A section of the northbound lane on the narrow, two-lane road slipped a half-dozen feet during early March 2016 storms. The road reopened on March 25 with temporary signals in place to alternate traffic in the southbound lane. Caltrans design teams are working on repair plans for the northbound lane, agency spokesman Vince Jacala said Wednesday. The preliminary cost estimate for the project is $5.5 million. The stricken northbound lane slipped 6 or 7 feet below the southbound lane, with a temporary concrete rail now separating them. Caltrans in late March installed metal beams and built a retaining wall to prevent further erosion. This section Route 121 handles an average of 1,800 autos daily. By contrast, the section of Route 121 in Napa that is central Imola Avenue handles 27,000 vehicles daily, according to Caltrans. But Route 121 near Circle Oaks is the key link between rural communities near Lake Berryessa and the city of Napa. Circle Oaks has about 180 homes and Berryessa Highlands has about 350 homes.
    (Source: Napa Valley Register, 5/1/2016)

    Capell Creek Bridge Repair (Bridge № 21-0009, 04-NAP-121, PM 020.29)

    In December 2011, the CTC approved for future consideration of funding a project in Napa County that will replace the Capell Creek Bridge (Bridge Number 21-0009) on Route 121 [04-NAP-121, PM 020.29]. The project is programmed in the 2010 State Highway Operation and Protection Program (SHOPP). The total estimated project cost is $10,880,000 for capital and support. Construction is estimated to begin in Fiscal Year 2012-13. The scope, as described for the preferred alternative, is consistent with the project scope programmed by the Commission in the 2010 SHOPP. A copy of the MND has been provided to Commission staff. The project will mitigate potential impacts to aesthetics to a less than significant level. Potential impacts to the vegetation in the project area will be mitigated through hydro-seeding with appropriate plant species. Oak trees removed will be replaced at a 3:1 ratio. Non-native trees will be replaced at a 1:1 ratio. Potential impacts to aesthetics will be mitigated by requiring the new bridge railing to have a finish pattern, surface texture, and coloration that mimic the original railing.

    In June 2021, it was reported that Caltrans has started work on a four-month long project to repair a century-old bridge along Route 121. The work along Route 121, which is also known in the area as Monticello Road, will contribute to the preservation of the Capell Creek Bridge, whose original construction dates to 1907. The work will take place between Circle Oaks Drive and Longhorn Ridge Road. The project will consist of repairing cracks, road breaks and replacing the northwest wingwall. The repair work requires crews to shift traffic for both directions of travel into a single northbound or southbound lane depending on the construction stages. A one-way traffic signal system and temporary concrete barriers are being used to guide traffic into one lane for use by both directions of travel during the construction work. Bicyclists are sharing the main traffic lanes with vehicular traffic within the project limits.
    (Source: Local News Matters, 6/24/2021)

    Naming Naming

    "Imola" Avenue; "Silverado" Trail, "Monticello" Road.

    Named Structures Named Structures

    Bridge 21-0075, at Imola Avenue in Napa, was named the "George M. Francis Memorial Bridge". It was built in 1932, and was dedicated in May, 1932. George M. Francis was the editor of the Napa Register beginning in 1872. In 1889 he called a town meeting in Napa and organized the town's first city government. It appears to have since been bypassed, but could be bridge 21-0086, NAP R004.47).
    [Information from Napa Chamber of Commerce, found by Phillip Pacier]

    In South Napa is the Maxwell Bridge. It was named in honor of nurseryman Thomas Maxwell, longtime Napa County Supervisor (1917 to 1948) and Napa County's first representative on the board of directors of the Golden Gate Bridge District. This bridge is being replaced by the Imola Avenue Bridge, and is being renamed the New Maxwell Bridge. This bridge will have plaques for 1) Mr. Maxwell, and 2) the Lodi construction worker who was killed during the building of the new structure late in 2003. It appears to be Bridge 21-0108 (NAP R005.30)
    [Information from a Napa Valley Register history article by Louis Ezettie, dated December 3, 1988, page 7-A]

Pre 1964 Signage History Pre 1964 Signage History

Route 121 was not defined as part of the initial state signage of routes in 1934. It is unclear what (if any) route was signed as Route 121 between 1934 and 1964.

Freeway Freeway

[SHC 253.1] Entire route. Added to the Freeway and Expressway system in 1959.

Other WWW Links Other WWW Links

Statistics Statistics

Overall statistics for Route 121:

Pre-1964 Legislative Route Pre-1964 Legislative Route

In 1933, Chapter 767 added the route from "[LRN 32] W of Los Banos to Fresno-Tracy West Side Highway near Centinella" to the highway system. In 1935, this was defined as LRN 121 in the highway code with the definition:

[LRN 23] West of Los Banos to [LRN 41] near Centinella

In 1961, Chapter 1268 changed the terminus to simply "[LRN 41]".

This was an unsigned segment connecting Route 152 to Route 33. It is part of present day Route 33.

Acronyms and Explanations:

Back Arrow Route 120 Forward Arrow Route 122

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Maintained by: Daniel P. Faigin <>.