*DRAFT* HUM 255 Corridor Management Plan

The California Department of Transportation (Caltrans) is the state agency responsible for planning, designing, building, operating, and maintaining the State Highway System (SHS). Caltrans is divided into 12 district offices. Caltrans District 1 has jurisdictional boundaries that cover the entirety of Lake, Mendocino, Humboldt, and Del Norte counties. The SHS in District 1 consists of 2 U.S. Routes, and 21 State Routes. 

System Planning establishes the long-range transportation plan for routes within the State Highway System. The System Planning process fulfills Caltrans’ statutory responsibility as owner/operator of the SHS (Gov. Code 65086) by evaluating existing conditions and proposing enhancements to the transportation system. System Planning develops Corridor Management Plans through a continuous, comprehensive, and cooperative process that considers the entire transportation system, including highways, local roads, transit, freight, and active transportation. The Caltrans mission is "improving lives and communities through transportation."

System Planning works with a range of data sources and long-range plans to provide essential information to internal and external stakeholders. On a statewide level, the Interregional Transportation System Plan (ITSP) is a document which provides direction to programs, districts, and partner agencies on the policies and strategies that should be considered when assessing the interregional transportation system and identifying improvements. The ITSP also provides policy direction for the development of the Interregional Transportation Improvement Program (ITIP). The Electronic Corridor Management Plan (eCMP) is a dynamic online planning document that identifies the existing and future route conditions as well as future needs for each route on the SHS. It is intended to act as a replacement for the Transportation Concept Report (TCR). These System Planning products are also intended as resources for stakeholders, including the public, partners, regional and local agencies.

This electronic Corridor Management Plan (eCMP) combines traditional corridor management plan analysis and narrative while incorporating Geographic Information Systems (GIS) for visual data representation. This eCMP provides historical background, traffic conditions, performance measures and any other information that is required to develop and support operational infrastructure improvements for the foreseeable future.

The route concept was development through public outreach to stakeholders and public agencies with jurisdiction within the corridor. Members of the public had opportunities to provide input at public meetings and the community of Manila was represented by Manila Moves, a privately funded community-based organization. Caltrans will maintain ongoing communication with public agencies and stakeholders to align agency strategies and activities, as well as to coordinate on projects within the corridor to maximize public benefit with the financial resources available.

Humboldt County

City of Arcata

City of Eureka

Humboldt County Association of Governments (HCAOG)

Humboldt Transit Authority

Humboldt County Department of Health & Human Services

Manila Moves

California State Coastal Commission

California State Coastal Conservancy

Humboldt Bay Harbor District

Table Bluff Rancheria

Great Redwood Trail Authority

Timber Heritage Association

Coalition for Responsible Transportation Priorities

Caltrans has an established collision surveillance and monitoring program, which identifies locations with collision concentrations and recommends safety improvements when warranted. Safety improvements at spot locations will be considered as necessary. Bridge replacement, storm damage and operational improvement projects will also be considered when necessary. These projects, in addition to safety projects, should be constructed to established State and Federal standards.

The Safe System Approach has been adopted at the State and federal levels to proactively address and mitigate the risks inherent in the transportation system. The Safe System Approach works by building and reinforcing multiple layers of protection to both prevent crashes from happening in the first place and minimize the harm caused to those involved when crashes do occur. A Safe System Approach incorporates the following principles:

• Deaths and serious injuries are unacceptable – The Safe System approach prioritizes the elimination of crashes that result in death and serious injury.
• Humans make mistakes – People will inevitably make mistakes and decisions that may lead to crashes, but road design should accommodate mistakes to make crashes less severe or deadly when they do happen. Examples of safe roads include physically separating people traveling at different speeds, dedicated times for people to move through a space, and alerting people to hazards and other road users.
• Humans are vulnerable – Human bodies have physical limits for tolerating crash forces. Reduce speeds helps reduce the severity of injury and risk of death. Designing a system that accommodates these vulnerabilities, particularly for bicyclists and pedestrians, is critical, such as additional time for drivers to stop and improving visibility.
• Responsibility is shared – The safety of all road users, including those who walk, bike, ride transit, or travel by modes other than a vehicle, is paramount. All strategies and voices should be heard, including all levels of government, non-profit and advocacy groups, researchers, engineers and the public. Everyone plays a role in preventing deaths and serious injuries on roads.
• Safety is proactive – Safety concerns should be identified and addressed before crashes happen.
• Redundancy is crucial – Reducing severe injury and deadly crashes requires all parts of the transportation system to be improved. If one part does not work, the other parts offer other layers of protection for people.

A survey conducted at the June 27, 2024 hybrid public outreach meeting for this CMP gathered information from attendees about their primary travel modes within the SR 255 corridor. The results of the survey can be found in Appendix E. The primary mode choice for travel within the corridor was motor vehicle. Only 15.25% of survey respondents reported regular bike ridership and none reported walking to recreational destinations in the community or commuting to work. The primary destination within the corridor is to community centers and public park or open spaces on the peninsula, such as the Samoa Dunes. Pedestrian exposure to highway traffic was stated as a concern for non-motorized access to local destinations.

District policy has historically allowed the use of multipurpose shoulders for bicycle travel on all District 1 highways.  Recent guidance from Director’s Policy (DP) 37 and Design Information Bulletin (DIB) 94, Complete Streets, has created new guidance for bicycle and pedestrian facilities on State routes. Dedicated bicycle and pedestrian facilities are limited within Segments 1, 2, and 3 (PM: 0.00/7.95), however non-motorized facilities are present within the City of Arcata (Segment 4).

The three bridges in Segment 1 have non-standard pedestrian or bicycle facilities, including shoulder width and safety railing.  Shoulders on the bridge decks are 4 feet. The 4-lane expressway segment in Eureka (PM 0.00 to PM 0.11) has sidewalks and 0- to 8-foot wide shoulders.

Segments 2 through 4 have an outside paved shoulder width of up to 8 feet. The width varies by segment with Segments 2, 3 and 4 having a minimum shoulder width of 4 feet, 2 feet, and 3 feet with Class II bike lanes in urban Arcata respectively. 

Segment 2 in Manila contains a 10-foot-wide, Class 1 Path within State right of way between Pacific Avenue and Lupin Drive (PM 3.65/3.96).

 In Segment 4, the City of Arcata (PM 8.352-8.803) contains a grid network of city streets, most with sidewalks, many with bike lanes. Class I paths exist; new sections are planned for construction. Some out-of-direction travel is needed for diverting onto parallel bicycle and pedestrian routes.

The general approach to providing Complete Streets on SR 255 includes four key types of improvement, which are further discussed in the relevant sections below.

1. Segment 1: Provide alternative options for bicycles and pedestrians wishing to use the Samoa Bridges until funding becomes available for bridge deck improvements.
2. Segments 2, 3, and 4: Provide support for the development of the Great Redwood Trail spur and other off-highway alignments as the preferred non-motorized facility between Arcata and Samoa.
3. Segment 2: Provide Enhanced Crossings on SR 255 to reduce the Level of Traffic Stress at highway crossings and re-connect the community of Manila.
4. Segment 2: Allow for greater delay of through-traffic in Manila for improvements that benefit local circulation, particularly for bicyclists and pedestrians.

Segment 1 of SR 255 provides the only access across Humboldt Bay to the peninsula. The three bridge spans were collectively completed in the early 1970s and have a design life of 80–100 years. Constructing bicycle and pedestrian facilities to State standards on the Samoa Bridges is not considered to be feasible within the 20-year time horizon of this plan.

Humboldt Transit Authority (HTA) has secured funding to provide micro-transit service from the Samoa Peninsula to both Eureka and Arcata. Micro-transit service supplements the limited fixed route transit service on the Samoa Peninsula by allowing those without motor vehicles to request a ride in an HTA shuttle van to the nearest bus stop in Eureka or Arcata as an alternate to having to walk or bike on the shoulder of SR 255. This service will be offered when regular fixed route service is available to extend the trip by transit.

The Redwood Transit System (RTS) serves SR 255, with five trips in each direction on weekdays, and two trips in each direction on Saturdays. These trips stop at the Manila Community Center which is currently the only stop along the route.

The RTS Green Line connects Manila to the Arcata & Mad River Transit Service (AMRTS) through the connecting bus stop at H Street & 6th Street in Arcata.

The Eureka Transit Service (ETS) also serves Manila. Headways for all Eureka Transit Service and Arcata and Mad River Transit Service routes are one bus per hour. There is no transit service for State Route 255 on Sundays.

Samoa is no longer served by fixed route transit service since the Samoa Transit System was suspended in July 2023 due to low ridership. To support Samoa Peninsula residents, HTA has proposed the implementation of a micro-transit service. For residents from Fairhaven to Manila, HTA will establish drop off and pickup points at key locations around Humboldt Bay, including the 3rd & H transit hub in downtown Eureka as well as at Grocery Outlet and at Target. Service would be provided on weekdays from 7 AM to 11 AM and from 1 PM to 6 PM, on Saturdays the service would be limited to 12 PM to 6 PM. This micro-transit service is estimated to serve 11,600 passenger trips per year, or 46 people per average weekday. Other details of the micro-transit service include:

• Call in dispatch
• 3 Grocery Bag Limit
• Service Animals Permitted
• Pets allowed in carriers
• 7 seats per vehicle
• Microtransit vehicles do not have bike racks
• Foldable scooters are allowed

State Route 255 is designated as a “California Legal” truck route. State highways are classified according to the largest size vehicle designed to utilize the route. The roadway geometry determines the maximum sized vehicle that can safely navigate the route.

Freight generators operating on the Samoa Peninsula are limited to the use of California Legal trucks due to SR 255 truck restrictions.  The Port of Humboldt Bay has stated that the Port is expected to operate unimpeded at full build-out with the existing truck restrictions.

Segment 1 will be prioritized to facilitate truck travel to meet the operational needs of the Port of Humboldt, with some consideration for the needs of transit and non-motorized modes. Segments 2, 3 and 4 will be designed to accommodate California Legal Trucks but the ultimate concept to support Complete Streets improvements in Segments 2 and 4 may increase truck travel times to a limited extent on SR 255 north of its intersection with Navy Base Road.

Rising temperatures are driving sea level rise through expanding ocean volumes and increasing polar ice melt, which impacts the coastal landscape adjacent to SR 255. When combined with storm surges or wave run up, any measurable rise in sea level poses a risk to existing low-lying sections of SR 255. Sea level rise data for this plan is sourced from the United States Geological Survey (USGS) Coastal Storm Modeling System (CoSMoS) map as published by Our Coast, Our Future (OCOF). To explore sea level rise data, please use the below link to the OCOF Hazard Map:

 Hazard Map – Our Coast, Our Future 

Rates of vertical land motion show that the land along State Route 255 is subsiding at higher rates than other coastal areas in California. Land subsidence compounds the effects rate of sea level rise. The localized variability of vertical land motion combined with sea level rise projections for the Humboldt Bay North Spit tide gage result in varying changes to sea level elevations across sections of Humboldt Bay so that mapped elevational changes should be seen as an average.

Temperature Change

The 2019 Caltrans Climate Change Vulnerability Assessment (CCVA) utilizes the "Change in The Average Maximum Temperature Over Seven Consecutive Days" to measure the effect of rapidly changing temperature on pavement and the need to consider temperature changes in road construction and maintenance. The area surrounding SR 255 is expected to see an increase in the average maximum temperature up to 2.3°F (1.26°C) by 2025 and up to 4.86°F (2.7°C) by 2055. An increase of between 5.0-9.9% in the Maximum Daily 100-Year Storm Precipitation is also forecast by 2055.

The adaptation decision-making process is a tool from the Federal Highway Administration produced to aid planners and project managers in accounting for the increasing impact of climate change in designing new infrastructure projects and assessing existing facilities. If being utilized for a new infrastructure project it is best to employ the use of the ADAP early in the planning stage to allow for the full consideration of project alternatives.

The area that SR 255 travels through contains the traditional homeland of the Wiyot Tribe, which is made up of Table Bluff Rancheria, the Blue Lake Rancheria, and the Bear River Rancheria. Due to the possibility of culturally sensitive areas existing at locations along SR 255, the Wiyot Tribe should be coordinated with and consulted early in the planning process, programming phases, and especially pre-construction.

No Naturally Occurring Asbestos (NOA) sites are shown on the US Geological Survey document “Reported Historical Asbestos Mines, Historical Asbestos Prospects, and Other Naturally Occurring Asbestos in California.” Aerially deposited lead is a potential concern, with the exception of Segment 1, which was not constructed until 1971.

Senate Bill 857 was enacted into law effective January 1, 2006 concerning anadromous fish passage. This bill requires Caltrans projects be constructed so that they do not present a barrier to anadromous fish passage at any life stage. Additionally, all projects on streams that currently or historically supported fish and affect culverts, bridges, or associated structures shall include a fish passage assessment according to National Marine Fisheries Service (NMFS) and California Department of Fish and Wildlife (CDFW) guidelines prior to commencing project design. Caltrans is also required to develop necessary passage corrections during project development in consultation with the CDFW.

Man-made barriers to anadromous fish migration include road and stream crossings, irrigation diversions, dams, and many other in-stream structures. Passage impediments affect adult and juvenile fish by delaying or preventing upstream and downstream migration, preventing the use of available habitat, and possibly inflicting injury or death. There are no fish passage barriers identified on SR 255.

Endangered, Threatened and Rare Species: The California Natural Diversity Database lists multiple species within one half mile of SR 255:

Pursuant to the Clean Air Act, all transportation plans, programs, and projects dependent on the United States Department of Transportation (DOT), metropolitan planning organizations (MPOs) or other recipients of funds under title 23 United States Code or the Federal Transit Laws (49 U.S.C. Chapter 53) must remain consistent and in compliance with the Clean Air Act. Conformance is determined through the Code of Federal Regulations (CFR), Title 40, Chapter 1, Subchapter C, Part 93, Subpart A. The conformance standards established in 40 CFR 1 (C)(93)(A) do not apply if the jurisdiction is already in attainment of federal air quality standards. Humboldt County is in attainment for both state and federal air quality standards, including the area surrounding SR 255. Therefore, projects and plans conducted within Humboldt County will still need to comply with CEQA and NEPA, however they will not need to meet these conformity standards.

All of SR 255 exists in a Tsunami Inundation Zone according to the California Department of Conservation. A tsunami has the potential to inundate, or flood, the entire route. In the case of a tsunami, an alternative route such as US 101 or Old Arcata Road can be used; however, no alternate route to Manila or Samoa exists.

Due to the location of SR 255 on or near the perimeter of Humboldt Bay, the route is susceptible to the effects of Sea Level Rise (SLR).

The system of levees surrounding Humboldt Bay, particularly in the Mad River Slough adjacent to SR 255, are at high risk of failing. Sea Level Rise and Climate Change Adaptation improvements are expected to require Coastal Development Permits.  Please see the sections on “Climate Change” and “Environmental Considerations” form more information on sea level rise, land subsidence and levee health.

The growth potential within the SR 255 corridor is primarily limited to Arcata and Samoa. The following is a summary of developments at the local level which may impact the function of the route or the overall route concept. For additional information on these projects, please see Appendix C.

• Samoa Town Master Plan: In June 2000, the 59-acre Samoa town site was subdivided into 96 individual parcels for resale. In addition to these 96 parcels, an additional 282 new residences were proposed for construction in the town site. At project buildout under cumulative conditions, projected traffic levels were considered to warrant improvements to SR 255 and New Navy Base Road.
• Nordic Aquafarms: This project proposes to construct a land-based fish Recirculating Aquaculture System (RAS) facility at the site of the decommissioned Samoa Pulp Mill. This project is estimated to produce 130 new jobs and increase truck volumes on Navy Base Road/SR 255.
• Humboldt Bay Offshore Wind Heavy Lift Multipurpose Marine Terminal: The Humboldt Bay Harbor District proposes to redevelop 180-acres on the Samoa Peninsula with a new multipurpose, heavy-lift marine terminal facility to support offshore wind energy leases. The Marine Terminal is located on the Samoa Peninsula of Humboldt Bay, off of Navy Base Road. At full build out the project is expected to result in 377 daily trips with 48 trips during the A.M. peak and 47 daily trips during the P.M. peak.
• Offshore Wind Lease Area: In December 2022, the federal Bureau of Ocean Energy Management (BOEM) auctioned multiple Renewable Energy Leases off the coast of Humboldt County, to be developed into deep water wind farms. The lease area is located 21-miles off the Humboldt County coast in federal waters. The National Environmental Policy Act review for this wind farm did not consider transportation impacts in the Humboldt Bay area because the project is not dependent upon the development at the Port of Humboldt Bay. The Final Environmental Assessment for this project indicates that at full build out, the facility will employ between 10-20 people.
• Arcata Gateway Plan: In July, 2024, the City of Arcata adopted a specific plan to re-zone 138 acres of land, primarily zoned as industrial to accommodate high-density, mixed use residential projects. Reductions in parking requirements and the development of robust multi-modal transportation facilities and services are planned to minimize congestion-related impacts to SR 255. The following improvements have not been evaluated for feasibility or for consistency with State standards or guidance. Additional coordination with the City will be needed prior to approving improvement concepts with the potential to affect SR 255 during implementation of the plan, including:
  • New Local Road Connections at postmiles 8.011 and 8.154,
  • A Class I Multiuse Path,
  • A Class I Multiuse Path Crossing,
  • High-Visibility Crosswalks/Hybrid Beacons,
  • A Class II Bike Lane Crossing.

The 2013 engineered feasibility study contained multiple options for widening the bridge decks to provide a separated path along the northbound and/or southbound edge of traveled way.  Four alternatives were outlined with the cost ranging from $17-44 Million (in 2013 dollars), including retrofits to the structure of the bridge. The travel lanes were narrowed from 12 to 11 feet wide in 2011, to widen the shoulder from 3 to 4 feet. Since the lanes are currently narrower than the standard 12-feet, further shoulder widenings are infeasible without widening the bridge decks. No sidewalks or separated pedestrian facilities currently exist on the Samoa Bridges. Pedestrians must share the shoulder with bicycles.

Humboldt Transit Authority is in the process of establishing a dial-a-ride service for residents of the Samoa Peninsula that need improved connections to transit services in Eureka and Arcata.  This service is expected to provide an alternate travel option for residents on the Samoa Peninsula that are unable to travel by personal vehicle across the Samoa Bridges.

The local road network in Manila is bisected by State Route 255, which results in local trips crossing the highway in order to access isolated parts of the community.  The 55 mile-per-hour speed limit and expressway designation through Manila are at odds with the community desire to make the community more walkable and bikeable. Community-based service organizations, such as the Manila Moves Group, have expressed a need for more pedestrian-friendly improvements along the route, citing high traffic speeds and a lack of pedestrian crossing facilities as a barrier to non-motorized travel.

Caltrans’ 2017 Transportation Concept Report for State Route 255 incorporated the findings from the 2005 Manila Transportation Plan and the 2013 Engineered Feasibility Study as part of the vision and long-range plan for the route. The majority of the improvements identified in previous planning efforts have yet to be funded or constructed. Many of the community-identified improvements are carried over into the 2025 Corridor Management Plan for State Route 255. 

Segment 1 is an expressway at its junction with US Route 101 in Eureka until it reaches the approach to the Eureka Channel Bridge. The three bridges that make up the Samoa Bridges are designated as freeway, with one interchange located on Woodley Island. From Navy Base Road to the Mad River Slough Bridge, SR 255 is designated an expressway.

The initial long-range concept was to construct SR 255 to a four-lane expressway, however the State legislature did not adopt SR 255 into the State Freeway and Expressway System. The entirety of Segment 2 is designated a two-lane expressway, however, Segment 2 has a wide right-of-way to allow for the future construction of a four-lane facility. Representatives of Manila have requested to rescind access control if the expressway designation will be an impediment to achieving the long-range transportation goals of the community.

Segment 3 is largely a two-lane conventional highway with short sections of four lane roadway and with a limited amount of access control. Segment 4 in the City of Arcata has a conventional highway designation and characteristics consistent with a main street-type facility. 

Caltrans long range plans consider each route for the possibility of relinquishment. District 1 considers the relinquishment of Segments 2, 3, and 4 as a potential long-term goal for the Department. A major barrier to relinquishment is that it can be expected to impose an additional financial burden on local agencies, as they will be responsible for continuing maintenance. 

Caltrans acknowledges that State Route 255 has utility for the state and region.  The route is an important route within the region due to providing the only access to the Port of Humboldt and as an alternative to US Route 101 during emergency road closures. The lack of redundancy within the local roadway network and the high maintenance cost of the route and bridges may potentially outweigh the benefits of local control or ownership.

No highway capacity-increasing projects are proposed within the 20-year planning horizon for SR 255. Projects to improve local circulation and non-motorized facilities will need to secure funding in order for implementation to occur. Projects requested as a result of public input include: enhanced highway crossings, intersection improvements, roundabouts, and non-motorized improvements.

 The District will explore the removal of the expressway designation for Segments 2 and 3 with the County of Humboldt as an approach to streamlining project delivery for improvements that support reconnected communities through Manila and other investments to improve the multimodal transportation network within the corridor.

 The Great Redwood Trail Spur right of way, adjacent to or parallel with SR 255 in Segments 2 through 4, is the preferred alignment for developing non-motorized facilities within the SR 255 corridor. Highway crossing improvements in Arcata and Manila may be necessary to provide connectivity to the trail.

 The City of Arcata has received grant funding to study potential modifications to the US 101/SR 255 interchange that would alter the roadway geometry on the over-crossing bridge deck for the benefit of non-motorized travel. The preferred solution would also reconfigure the freeway ramp intersections and improve crossing safety on SR 255 among other non-motorized improvements.

The following list of improvements to State Route 255 have been included in the 20-year planning horizon. These candidate projects were identified through public outreach. Not all of the improvements identified may be completed in the 20-year planning horizon due to funding limitations or other constraints. It is important to note that features identified in the planning concept are conceptual in nature and may be modified in part or in whole during project development, based on presently unforeseen planning, engineering, funding, and environmental considerations.

• AADT- Average Annual Daily Traffic
• AADTT – Annual Average Daily Truck Traffic
• ADAP – Adaptation Decision-Making Assessment Process
• ATP – Active Transportation Plan
• BLM –Bureau of Land Management
• BOEM – Bureau of Ocean Energy Management
• BY – Base Year
• CAIP –Corridor Climate Adaptation and Implementation Plan’s
• CCVA – Climate Change Vulnerability Assessment
• CDFW – California Department of Fish and Wildlife
• DP – Directors Policy
• DVMT – Daily Vehicle Miles Traveled
• EFS – Engineered Feasibility Study
• ETS – Eureka Transit Service
• E&TS – Engineering and Traffic Survey
• FARS – Federal Accident Reporting System
• GIS – Geographic Information System
• GRT – Great Redwood Trail
• HCAOG – Humboldt County Association of Governments
• HCM – Highway Capacity Manual
• HCS – Highway Capacity Software
• HY – Horizon Year
• IRRS – Interregional Route System
• ITIP – Interregional Transportation Improvement Program
• ITSP – Interregional Transportation Strategic Plan
• KPRA – King Pin to Rear Axle
• LOS – Level of Service
• MPH- Miles Per Hour
• NMFS – National Marine Fisheries Service
• NOA – Naturally Occurring Asbestos
• PAD – Passage Assessment Database
• PM – Post Mile
• RTS – Redwood Transit System
• SAMSIP – South Arcata Multi-Modal Safety Improvements Plan
• SHOPP – State Highway Operation and Protection Program
• SHS – State Highway Systems
• SHSP – California Strategic Highway Safety Plan
• SLR – Sea Level Rise
• SR – State Route
• SWITRS – Statewide Integrated Traffic Records System
• TASAS- Traffic Accident Surveillance and Analysis System
• TCR – Transportation Concept Report
• USFS – United States Forestry Service
• VMT – Vehicle Miles Traveled

AADT – Annual Average Daily Traffic is the total volume for the year divided by 365 days. The traffic count year is from October 1st through September 30th. Traffic counting is generally performed by electronic counting instruments moved from location to location throughout the State in a program of continuous traffic count sampling. The resulting counts are adjusted to an estimate of annual average daily traffic by compensating for seasonal influence, weekly variation and other variables which may be present. Annual ADT is necessary for presenting a Statewide picture of traffic flow, evaluating traffic trends, computing collision rates, planning and designing highways and other purposes.

Bikeway Class I (Shared Use Path) – Provides a completely separated right of way for the exclusive use of bicycles and pedestrians with cross flow by motorists minimized.

Bikeway Class II (Bike Lane) – Provides a striped lane for one-way bike travel on a street or highway.

Bikeway Class III (Bike Route) – Provides for shared use with pedestrian or motor vehicle traffic.

Bikeway Class IV (Bike Route) – For the exclusive use of bicycles and includes a separation required between the separated bikeway and the through vehicular traffic. The separation may include, but is not limited to, grade separation, flexible posts, inflexible posts, inflexible barriers, or on-street parking.

Capacity – The maximum sustainable hourly flow rate at which persons or vehicles reasonably can be expected to traverse a point or a uniform section of a lane or roadway during a given time period under prevailing roadway, environmental, traffic, and control conditions.

Capital Facility Concept – The 20-25 year vision of future development on the route to the capital facility. The capital facility can include capacity increasing, State Highway, bicycle facility, pedestrian facility, transit facility (Intercity Passenger Rail, Mass Transit Guideway etc.), grade separation, and new managed lanes.

Complete Streets – A complete street is a transportation facility that is planned, designed, constructed, operated, and maintained to provide comfortable and convenient mobility, and improve accessibility and connectivity to essential and popular community destinations for all users, regardless of whether they are traveling as pedestrians, bicyclists, public transportation riders, or drivers.

Concept LOS – The minimum acceptable LOS over the next 20-25 years

Conceptual – A conceptual improvement or action is a project that is needed to maintain mobility or serve multimodal users, but is not currently included in a financially constrained plan and is not currently programmed.

Corridor – A linear geographic area with one or more modes of transportation that facilitates the movement of people and goods, supports the economy, and connects communities.

Facility Type – The facility type describes the state highway level of access control. This could be freeway (full access control/grade separation), expressway (partial access control/limited at-grade intersections), or conventional highway.

Freight Generator – Any facility, business, manufacturing plant, distribution center, industrial development, or other location (convergence of commodity and transportation system) that produces significant commodity flow, measured in tonnage, weight, carload, or truck volume.

Functional Classification – A method used by the Federal Highway Administration for determining the roll of a highway in the overall system. Functional Classification is used in determining eligibility for Federal funding programs.  

Headway – The time between two successive transit vehicles as they pass a point on the roadway, measured from the same common feature of both vehicles.

ITS – Intelligent Transportation System improves transportation safety and mobility and enhances productivity through the integration of advanced communications technologies into the transportation infrastructure and in vehicles. Intelligent transportation systems encompass a broad range of wireless and wire line communications-based information and electronics technologies to collect information, process it, and take appropriate actions. This includes features such as coordinated traffic signal hardware, changeable message signs, CCTV Cameras, data collection technology, etc.

LOS – Level of Service is a qualitative measure describing operational conditions within a traffic stream and their perception by motorists. A LOS definition generally describes these conditions in terms of speed, travel time, freedom to maneuver, traffic interruption, comfort, and convenience. Six levels of LOS can generally be categorized as follows:

• LOS A describes free flowing conditions. The operation of vehicles is virtually unaffected by the presence of other vehicles, and operations are constrained only by the geometric features of the highway.
• LOS B is also indicative of free-flow conditions. Average travel speeds are the same as in LOS A, but drivers have slightly less freedom to maneuver.
• LOS C represents a range in which the influence of traffic density on operations becomes marked. The ability to maneuver with the traffic stream is now clearly affected by the presence of other vehicles.
• LOS D demonstrates a range in which the ability to maneuver is severely restricted because of the traffic congestion. Travel speed begins to be reduced as traffic volume increases.
• LOS E reflects operations at or near capacity and is quite unstable. Because the limits of the level of service are approached, service disruptions cannot be damped or readily dissipated.
• LOS F a stop and go, low speed conditions with little or poor maneuverability. Speed and traffic flow may drop to zero and considerable delays occur. For intersections, LOS F describes operations with delay in excess of 60 seconds per vehicle. This level, considered by most drivers unacceptable often occurs with oversaturation, that is, when arrival flow rates exceed the capacity of the intersection.

Multi-modal – The availability of transportation options using different modes within a system or corridor, such as automobile, subway, bus, rail, or air.

Peak Hour – The hour of the day in which the maximum volume occurs across a point on the highway.

Peak Hour Volume – The hourly volume during the highest hour traffic volume of the day traversing a point on a highway segment. It is generally between 6 percent and 10 percent of the ADT. The lower values are generally found on roadways with low volumes.

Peak Period – is a part of the day during which traffic congestion on the road is at its highest. Normally, this happens twice a day, once in the morning and once in the evening; the time periods when the most people commute. Peak Period is defined for individual routes, not a District or Statewide standard.

Planned– A planned improvement or action is a project in a long-term financially constrained plan, such as an approved Regional Transportation Plan (RTP or MTP) or Capital Improvement Plan.

Post Mile – A post mile is an identified point on the State Highway System. The post mile values increase from the beginning of a route within a county to the next county line. The post mile values start over again at each county line. Post mile values usually increase from south to north or west to east depending upon the general direction the route follows within the State. The post mile at a given location will remain the same year after year. When a section of road is realigned, new post mile (usually noted by an alphabetical prefix such as "R" or "M") are established for it. If relocation results in a change in length, "post mile equations" are introduced at the end of each relocated portion so that post miles on the remainder of the route within the county will remain unchanged.

Programmed – A programmed improvement or action is a project in a near-term programming document identifying funding amounts by year, such as the State Transportation Improvement Program or the State Highway Operations and Protection Program

Route Designation –A route’s designation is adopted through legislation and identifies what system the route is associated with on the State Highway System. A designation denotes what design standards should apply during project development and design. Typical designations include but not limited to National Highway System (NHS), Interregional Route System (IRRS), Scenic Highway System, etc.

Rural – Fewer than 5,000 in population designates a rural area. Limits are based upon population density.

System Operations and Management Concept – Describe the system operations and management elements that may be needed within 20-25 years. This can include Non-capacity increasing operational improvements (Auxillary lanes, channelization's, turnouts, etc.), conversion of existing managed lanes to another managed lane type or characteristic. These can include High Occupancy Vehicle (HOV) lanes High Occupancy Tolling (HOT) lanes, Traffic Management Systems (TMS) Field Elements, Transportation Demand Management, and Incident Management.

Traffic Management Systems (TMS) – Processes and associated tools, field elements and communications systems used to manage traffic. Can include closed circuit televisions, changeable message signs, traffic monitoring detection stations, highway advisory radios, freeway ramp meters, roadway weather information systems, traffic signals, traffic census stations, and extinguishable message signs.

Urban – According to definitions in 23 U.S.C. 101(a), areas of population greater than 5,000 qualify as urban for transportation purposes. Urban areas include FHWA defined small urban areas (population of 5,000 – 49,999) and urbanized areas (population of 50,000 +).

1.  Corridor Planning Guidebook 
2. TASAS
3. Caltrans District 1 Internal Data Collection
4. 2017 State Route 255 Transportation Concept Report
5. 2002 California State Highway Log, District 1
6.  About Caltrans | Caltrans 
7. 2021 Caltrans District 1 Active Transportation Plan
8. Design Information Bulletin - 94
9.  Section 3. Criteria - Highway Functional Classifications - Related - Statewide Transportation Planning - Processes - Planning - FHWA (dot.gov) 
10. United States American Community Survey (ACS)
11. Humboldt County GIS Based Zoning Map
12. Caltrans Traffic Census
13. Highway Capacity Manual
14. Caltrans Peak Hour Data
15. Caltrans Truck Traffic Census
16.  What Is a Safe System Approach? | US Department of Transportation 
17.  The Safe System | Office of Traffic Safety (ca.gov) 
18.  CalFIRE FRAP 
19. 2019 Caltrans Climate Change Vulnerability Assessment
20. Caltrans District 1 Division of Right-of-Way
21. California Manual for Setting Speed Limits
22. California Streets and Highways Code
23. FHWA Vulnerability Assessment and Adaptation Framework
24. 2023 Truck Networks on California State Highways
25.  Quick Guide: Truck Lengths & Routes | Caltrans 
26. CRS Functional Classification GIS (  https://dot.ca.gov/programs/research-innovation-system-information/office-of-highway-system-information-performance/functional-classification) 
27.  https://dot.ca.gov/programs/research-innovation-system-information/caltrans-facts 
28.  Hazard Map – Our Coast, Our Future 

California Streets and Highways Code Section 890.4 defines “bikeway” to mean all facilities that provide primarily for, and promote, bicycle travel. These facilities are divided into four categories.

• (a) Bike paths or shared use paths also referred to as “Class I bikeways,” which provide a completely separated right-of-way designated for the exclusive use of bicycles and pedestrians with crossflows by motorists minimized.
• (b) Bike lanes, also referred to as “Class II bikeways,” which provide a restricted right-of-way designated for the exclusive or semi exclusive use of bicycles with through travel by motor vehicles or pedestrians prohibited, but with vehicle parking and crossflows by pedestrians and motorists permitted.
• (c) Bike routes, also referred to as “Class III bikeways,” which provide a right-of-way on-street or off-street, designated by signs or permanent markings and shared with pedestrians and motorists.
• (d) Cycle tracks or separated bikeways, also referred to as “Class IV bikeways,” which promote active transportation and provide a right-of-way designated exclusively for bicycle traffic.

• STAA - Surface Transportation Assistance Act of 1982, federal funding authorization that declared, among other things;
  • Semitrailers up to and including 48 feet in length are exempt from state kingpin to rear axle (KPRA) and overall combination length limits,
  • Semitrailers over 48 feet long and up to and including 53 feet in length are exempt from state overall length limits. (These semitrailers are subject to state KPRA limits in California.),
  • Double trailers in combination where each does not exceed 28.5 feet in length are exempt from any state overall length limits.
  • Federal length rules apply to these combination vehicles only when operating on a federally declared system of highways called the National Network and the state and local determined terminal access and service access highways.
  • Note: Tour buses up to 45 feet long (motorcoaches) were added to the federal regulations under the Intermodal Surface Transportation Efficiency Act of 1991 (ISTEA). Motorhomes (housecars) up to 45 feet in length were legalized in California in October 2001. Although highway restrictions apply to both these vehicle types, they may operate beyond the STAA Network. However, the Motorcoach and Motorhome Network map defines highway access restrictions imposed at the limits of turning performance (i.e., the 45 feet vehicles would need to cross centerlines).
• National Network – federally designated state highways for STAA vehicles as defined and listed in the Federal Code of Regulations, Title 23, Part 658 (23CFR658) and 658.23 Appendix A.
• Terminal Access – state and local agency highways designated for “reasonable access” to/from the National Network by STAA vehicles as provided for in the CVC 35401.5(c) and (d). All transitions (egress) from National Network to Terminal Access highways, critical decision points (all turns) and Terminal Access end points should be so designated with a G66-56(CA) sign.
• STAA Network – the California network of Terminal Access and National Network highways. A map and Truck Route List identifying the STAA Network (includes State highway system only, does not include local streets and roads) are available from Office of Traffic Engineering in Caltrans’ Division of Traffic Operations.
• Service Access (SA) – state and local agency highways identified for service use by STAA vehicles. Service access is limited to 1 mile off the STAA network and must be “identified.” Identification may include a map indicating service access for STAA vehicles, an approved list, or by G66-55(CA) signs.
• STAA trucks – are truck tractor-semitrailer combinations, or doubles with a long length configuration such that the vehicles may operate legally only on the STAA Network and SA routes.

The STAA Truck Service (G66-55(CA)) Sign may be placed on the STAA Network to identify locations where STAA trucks may exit the network to obtain services as provided for by CVC 35401.5, and STAA trucks shall not exit the STAA Network to obtain services unless the G66-55(CA) sign indicates egress.

STAA Truck Service (G66-55(CA)) signs shall be provided as follows:

1. Access – All the following requirements shall be met:
   1. Fuel, food, lodging and/or repair facilities shall be located within 1 mile of the point of ingress and egress from the designated system.
   2. Ramps, intersections and streets shall have adequate turning radii and lane widths to safely accommodate STAA trucks.
   3. The service being made accessible shall have parking provisions for STAA trucks, or alternative parking within 1 mile shall be identified.
2. Facilities – Two of the four services - fuel, food, lodging & repair - shall be provided:
   1. Fuel (Diesel) - Fuel is available at least 12 hours during the working day.
   2. Food - Conforms to requirements for Food (D9-8) signs in this section.
   3. Lodging - Conforms to requirements for Lodging (D9-9) signs in this section.
   4. Repair Services - Oil, tire repair, engine and brake services are available.
3. Concurrence:
   1. The proposal for G66-55(CA) signing has written concurrence by the local jurisdiction(s) having responsibility for maintenance of the roadways within 1 mile of ingress/egress.
4. Sign Placement:
   1. The G66-55(CA) sign on the STAA Network shall be displayed in advance of the ramp or intersection.
   2. Although no follow-up signing is required, trailblazer signs may be used where applicable.

STAA Truck Terminal Access (G66-56(CA)) signs may be placed to identify Terminal Access routes leading from the National Network as trailblazers and to indicate the end of a Terminal Access route. State routes may be designated Terminal Access only if the curves, ramps, and intersections meet the geometric criteria for STAA trucks, including adequate turning radii and lane width. The Truck Terminal Access designation requirements for a State Route are as follows:

1. State route segments under consideration for Terminal Access shall meet all geometric criteria (see Paragraph 60) for STAA trucks.
2. The end of any Terminal Access route segment shall be signed as such.
3. Trail-blazing signs shall be placed at decision points indicating direction(s) a STAA truck may proceed.
4. The G66-56(CA) sign shall be placed in advance of the ramp or intersection where a STAA truck may exit the National Network or the designated Terminal Access routes.

The geometric criteria for using the STAA design vehicle to design or analyze the intersection, ramp, or curve are described in Topic 404 in the Caltrans Highway Design Manual. If the Terminal Access route ends without connecting to another STAA route, then the geometric criteria also include ensuring that an adequate turn-around location is available for all STAA vehicles 24 hours per day, 7 days per week.

Stakeholder coordination meetings were held throughout the plan development process. 

Manila Moves (Meeting Date: 5/30/2024) is a community-based organization which advocates for community connectivity in Manila. This organization was primarily concerned with installing roundabouts at the intersections at Dean/Pacific Avenue and Lupin Avenue, however they were also interested in traffic calming, trail extensions and other short term steps such as enhanced crosswalks and pedestrian hybrid beacons that can be taken by residents to improve the livability of residents on the corridor. 

The Humboldt Transit Authority (Meeting Date: 6/7/2024) has indicated that ridership on the Samoa Peninsula is low due to its low population. To provide transit access to communities on the peninsula the HTA is beta-testing on-demand, paratransit or dial-a-ride service as well as microtransit/micromobility options to expand service on the Peninsula. This would be an on-demand model operating daily from 7AM-6PM and would feed into the Redwood Transit System through either Arcata or Eureka. 

City of Arcata 6/4/2024 is the land use authority for all of segment 4. City plans for this segment involve the South Gateway Project/South Arcata Multimodal Project which includes a crossing with the Northern terminus with US 101, and a Gateway Electronic Bulletin on SR 255 in Phase III. City staff anticipates a 2026 completion date for S. Gateway Project Plan. Concerns included the variable speed limits on SR 255 with limits posted at 55 mph which transition to 25 mph. 

City of Eureka (Meeting Date: 6/3/2024) noted that Myrtle Avenue bike improvements are planned from the city limits to 6th Street and that the Eureka Bike Plan is in the works. A few occasions, City Council has expressed a desire to prohibit truck traffic on 6th & 7th Streets. Preventing left turns from Myrtle onto 4th Street. City staff also noted collision concerns on the corner of 3rd and SR 255. In response District 1 developed a collision analysis report for the intersections of SR 255 with US 101. 

The Humboldt Bay Harbor District (Meeting Date: 6/6/2024) has asked to review a draft copy of the Freight Section of this plan prior to publication. A major topic of discussion was the Humboldt Bay Wind Terminal. The agency does not anticipate that the site will exceed historic employment. This follows from a DEIR published in March 2024 which indicated that a maximum of 200 people will be on site at any given time. Additionally, there is potential to use dredge materials produced by the project for sea level rise protection projects. 

The Humboldt County Association of Governments (HCAOG) (Meeting Date: 5/17/2024) is a joint powers agency composed of the seven incorporated cities (Arcata, Blue Lake, Eureka, Ferndale, Fortuna, Rio Dell, Trinidad), and the County of Humboldt. This agency in response to low transit ridership on the Samoa Peninsula is coordinating with the Humboldt Transit Authority to test mobility to fill gaps in service on the Samoa Peninsula. After the Danco Apartments were built there was an agreement to provide transit access, but this was underutilized. However traditional transit service sometime in the future will still be considered as feasible. 

The Humboldt County Department of Planning & Public Works (Meeting Date: 6/11/2024) introduced the idea of splitting Segment 2, for the purpose of providing greater flexibility in planning for Manila. This agency in light of Caltrans’ limited resources prioritized safe crossings at Lupin Avenue and that a roundabout would provide significant traffic calming.  

The Humboldt County Department of Health & Human Services (Meeting Date: 7/23/2024) was consulted in order to develop our understanding of equity concerns and disadvantaged communities on the Samoa Peninsula. Outreach is generally conducted on an “as-needed” basis through direct interviews with residents and houseless people. The data the county gathers and maintains includes homeless population size, drug use and demographic information. However not much transportation-based data is maintained by this office. They noted that in regard to the houseless population, most do not have cell phones and cannot take advantage of dial-a-ride systems, many have pets and/or carts which limits transit options, and that most need to make trips to Eureka where the majority of services are located. Further coordination with Caltrans was welcomed, and if such coordination is desired then Caltrans will need to contact the county on a plan-by-plan basis. 

The Great Redwood Trail Agency (Meeting Date: 6/12/2024) sees opportunity in coordinating on projects. GRT right of way runs adjacent to and parallel with 255 within segments 2, 3, & 4 255 for miles and construction in this space can supplement the state route. In particular the organization is interested in connectivity on Dean/Pacific and Lupin as well as a Bike/ped access through Vance Ave. The GRTA also requested that this document call out opportunities for mitigation projects. 

The Timber Heritage Association (Meeting Date: 6/13/2024) would like to engage in coordination with the Great Redwood Trail Agency and Caltrans on developing a “Rails With Trails” program. In this case the North Coast Railroad Authority right-of-way would be utilized for train trips while the Great Redwood Trail is relocated to the highway shoulder where bikes/peds and speeder cars will not mix. 

State Coastal Comission (Meeting Date: 6/7/2024) is a state agency that manages control of land and public access along the state's coastline. Issues noted included sea level rise and saltwater inundation of land surrounding SR 255. These issues will be brought to the forefront if the GRT concept is developed, as this trail will run directly adjacent to Arcata Bay west of the Mad River Slough. The agency also informed the district of a few opportunities for developing a strong plan for coastal features, these being the Local Coastal Development Grant, as well as updated environmentally sensitive areas mapping and aerial imagery. 

To gather the feedback of our Tribal Government partners, District 1 attended the Wiyot Quarterly Cultural Meeting (Meeting Date: 6/21/2024). They requested that they be provided an opportunity to review this document in draft form prior to final publication. 

Citizens for Responsible Transportation Priorities (Meeting Date: 7/25/2024)