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State Highway Types
State Highway Types

Highways vs. Freeways

The California State Highway code defines a number of different types of highways:

"State highway"
Any highway which is acquired, laid out, constructed, improved or maintained as a State highway pursuant to constitutional or legislative authorization. [SHC Sect 24]. Elsewhere, this is defined as a way or place of whatever nature, publicly maintained and open to the use of the public for purposes of vehicular travel. Highway includes street.
A highway in respect to which the owners of abutting lands have no right or easement of access to or from their abutting lands or in respect to which such owners have only limited or restricted right or easement of access. If, in the judgment of the commission or the director, the public interest would be advanced thereby, a freeway, as defined herein, may be denominated a "controlled access highway". In all other respects, the "controlled access highway" shall be subject to all provisions of this code pertaining to freeways. [SHC Sect. 23.5]

California Freeway and Expressway System

A statewide system of freeways and expressways and connections thereto, creating a comprehensive system of access-controlled freeways and expressways throughout the State. Within this system a "freeway" is defined as a divided arterial highway for through traffic with full control of access and with grade separations at intersections, while the "expressway" is defined as an arterial highway for through traffic which may have partial control of access, but which may or may not be divided or have grade separations at intersections.[SHC Sect 250-252, 257]

Designation as a freeway does not mean the route is constructed to freeway standards; rather, it was planned to be a freeway.

Expressways are a unique beast. Most formal expressways are County Routes, usually in the San Francisco Bay Area (specifically, Santa Clara county). The Santa Clara County Expressway Network is a 377-mile network of extra-wide streets that haul commuters from the Almaden Valley to Milpitas to Palo Alto. They carry nearly 498,000 vehicles a day. More than four of five valley residents use the expressways at least several days a week, and 37 percent of commuters take an expressway to work. County leaders turned to the expressway system when building high-speed highways took too long. In the early 1950s as the Cold War heated up and defense industries blossomed throughout Santa Clara County, thousands moved here for high-paying jobs. But traffic lights still dotted US 101 and Route 237, and I-280 wouldn't be completed until 1965. Route 85 wouldn't get off the drawing board until 1994. County leaders decided to build their own roads, passing a property tax increase in 1960 to begin construction of the first phase of expressways. A second phase—upgrading the current roads into freeways—was to have been paid by a second bond measure in 1974, but it was defeated.

California Scenic Highway System

Those portions of the state highway system which, together with the adjacent scenic corridors, require special scenic conservation treatment. [SHC Section 260].

To protect and enhance the natural beauty of California highway corridors, the state Legislature created the State Scenic Highway Program in 1963. The first Scenic Highway designation was awarded in 1965 for a 72.3-mile segment of Route 1 in Monterey County. Note that many highway corridors are eligible for Scenic Highway status, but receiving an official designation requires the local government to apply to Caltrans for approval and adopt a Corridor Protection Program. The local governing body must develop and implement measures that strictly limit development and control outdoor advertising along the scenic corridor. As of 2017, In California, 70 segments of 42 state highways have official recognition as a State Scenic Highway. In addition, following the same program requirements that apply to state routes, eight segments of seven county roads in California have obtained state recognition as an officially designated County Scenic Highway.

According to data released by Caltrans in 2019, only 28 percent of the roadways that have been listed as eligible have ended up becoming Scenic Highways. None of them span multiple counties.

The Scenic Highway designation reflects strong support by area residents and local government, including a written proposal and a detailed visual assessment of the route. The city and the county must formally endorse the application to Caltrans. A Scenic Highway must “traverse an area of outstanding scenic beauty” and is defined by the breadth of the natural landscape that can be seen by its travelers, the quality of that landscape, and the extent to which land development fetters that enjoyment. Only legislators can make that decision by enacting their opinion into law. And only transportation authorities can ensure it, looking for policies put in practice to limit visual intrusions to a max of 25 percent across the scenic driving landscape.
(Partial source: Davis Enterprise, "Almost Scenic 128", Sept 2020)

Being eligible isn’t enough. A local government such as Napa County must prepare a scenic highway proposal that includes a survey of the visual highlights. The proposals must be discussed at a public meeting. Then the paperwork goes to Caltrans. Once Caltrans accepts the proposal, the local government creates a corridor protection program that details how the scenic views will be protected. Then Caltrans decides whether to designate or not.

The legislative definition is just the start of the process, just like the legislative definition of something as part of the Freeway and Expressway system doesn't mean it is actually a freeway. A route can become part of the signed state scenic highway system provided it qualifies visually and five standards have been put in place. These standards are ensured by the Department of Transportation (Caltrans) through an iterative approval process with local authorities that focuses on a “corridor protection program” to shape land use. This starts when local officials — either as a group or county-by-county — conduct an assessment of which stretches of roadway are eligible for official designation according to that max 25 percent visual intrusion rule. They must then submit a “Resolution of Intent package” — which includes a letter from the local governing body, maps of the corridor and existing zoning, an overlay of development within that corridor, a narrative of the routes scenic elements and a videotape — all sent to Caltrans via the local district office.
(Partial source: Davis Enterprise, "Almost Scenic 128", Sept 2020)

If a Caltrans committee approves the package, in part or, perhaps less likely, in its entirety, a recommendation to designate the highway as scenic will be forwarded to the Caltrans Director who makes the final call. Sometimes the director will request additional information or clarification, but typically the director will officially designate the route per committee request. Once designated, Caltrans monitors the corridor at least every five years and may pull the designation if the corridor enforcement program has become ineffectual. If the package is ultimately not approved, Caltrans says “it is not advisable to continue seeking official designation.”
(Partial source: Davis Enterprise, "Almost Scenic 128", Sept 2020)

Threre is a collection of Scenic Highway Guidelines at (link currently broken in Caltran's accessibiliy update -- it should be available on this page after the update). After being defined in the SHC as eligible, cities and/or counties (hereafter referred to as local governing bodies) must develop and implement a Corridor Protection Program containing five legislatively required elements, generally accepted as land use planning standards. That then has to be reviewed and approved before there is signage.

As for the Corridor Protection Program:

The five legislatively required elements of corridor protection are:

  1. Regulation of land use and density of development (i.e., density classifications and types of allowable land uses),
  2. Detailed land and site planning (i.e., permit or design review authority and regulations for the review of proposed developments),
  3. Control of outdoor advertising (i.e., prohibition of off-premise advertising signs and control of on-premise advertising signs),
  4. Careful attention to and control of earthmoving and landscaping (i.e., grading ordinances, grading permit requirements, design review authority, landscaping and vegetation requirements), and
  5. The design and appearance of structures and equipment (i.e., design review authority and regulations for the placement of utility structures, microwave receptors, wireless communication towers, etc.).

Designation of highways signed as Scenic Highways requires a partnership between local landowners and their local government, and in turn that local government with the state government, is exactly what lawmakers say they envisioned with the spirit of the Scenic Highway law: to encourage buy-in at the local level in order to protect California’s diminishing natural resources while at the same time increasing the value of those natural resources to Californians. The establishing legislation recognized then that a growing California would mean a growing number of highways and that scenic roadway may be developed into freeways where it should not be. By regulating site planning, such as what’s permitted to be built on hillsides, the state legislation says “giving the utmost attention to scenic values” is the only way to “with the co-operative efforts of local government agencies” to together “not only add to the pleasure of the residents of this State” but also “play an important role in encouraging the growth of the recreation and tourist industries upon which the economy of many areas of this State depend.”
(Partial source: Davis Enterprise, "Almost Scenic 128", Sept 2020)

There's a lot more information on scenic highways at

Note that there’s no special funding, immediate tourism windfall, or accolade that comes with a “scenic highway” becoming a “Scenic Highway.” The only benefit is the sign, emblazoned with a poppy.
(Partial source: Davis Enterprise, "Almost Scenic 128", Sept 2020)

California Historic Parkway System

Those portions of the state highway system that (1) were constructed prior to 1945; (2) have been recognized by CalTrans or the Office of Historic Preservation in the Department of Parks and Recreation as having historical significance, including notable landmarks, historical sites, or natural or human achievements that exist or that occurred during the original construction of the parkway or in the immediately adjacent land area through which the parkway currently passes; (3) are bounded on one or both sides by federal, state, or local parkland, Native American lands or monuments, or other open space, greenbelt areas, natural habitat or wildlife preserves, or similar acreage used for or dedicated to historical or recreational uses; and (4) are traversed, at the time of designation and by the department's best count or estimate using existing information, by not less than 40,000 vehicles per day on an annual daily average basis. [SHC Section 280]

Classified Landscaped Freeway

A classified landscaped freeway is a section of freeway with planting that meets the criteria of the State Outdoor Advertising Regulations, Section 2500-2513, and assists in the control of Outdoor Advertising Displays. This is more than just having vegetation around the freeway. Plantings that consist of native vegetation and revegetation that are considered “functional” are not "classified landscaping". The designation affects off-premise displays. Off-premise displays advertise offsite products and businesses. Caltrans has no control over on-premise displays, which advertise the on-site business. Signs that are adjacent to a section of landscaped freeway can only be for on-premise displays. Next to a landscaped freeway, off-premise displays are not allowed per the Outdoor Advertising Regulations and Caltrans would not approve a permit for the off-premise panel.

To qualify for landscape status, plantings must be (a) within the state right of way; (b) continuous (no gaps ≥ 200’); (c) ornamental (not functional); (d) at least 1000' long; (e) on at least one side of the freway; and (f) require reasonable maintenance. Ornamental plants are lawns, trees, shrubs, flowers, or other plantings designed primarily to improve the aesthetic appearance of the highway. Inert material specifically placed to highlight the ornamental vegetation is considered part of the ornamental vegetation. In contrast, functional plantings are vegetation planted primarily for soil erosion control, traffic safety, reduction of fire hazards, covering soundwalls or fences; and traffic noise abatement or other non-ornamental purposes. A single row of plantings in the median is considered a functional planting. Reasonable maintenance means that a plant when planted requires maintenance on a regular basis to maintain it in a healthy and attractive condition. The fact that as a plant matures, it may require less maintenance than when first planted is not interpreted to mean it does not require reasonable maintenance. Maintenance means any of the following: watering, fertilizing, spraying, cultivating, pruning, cutting, mowing, replacing, weed control, washing, pest control, disease control, litter removal, or other similar plant care procedures.

Outdoor advertising displays require a permit from Caltrans if they are within 660 feet from the edge of the right-of-way and viewed primarily by persons traveling on the main-traveled way of the freeway. Permit Requirements are available on the Internet at Some of the requirements include: the location must be zoned commercial or industrial; the applicant must have property owner consent; the applicant must have building permit from local agency; there must be a business activity within 1,000 feet of proposed display; and the display may not be located adjacent to a landscaped freeway or scenic highway. In addition the display must be 500 feet from any other permitted display and not exceed 1,200 square feet in size. More details can be found in the briefing at

However, there are some special rules when relocating displays. Independent of the definition of a Landscaped Freeway, if an agreement to relocate advertising displays from within one area of a city or county to an area adjacent to a freeway right-of-way has been entered into between a city or county and the owner of an advertising display, then a “landscaped freeway” does not include the median of a freeway right-of-way. Digital billboards (message centers) may also be allowed: A relocated advertising display may be converted to a message center pursuant to a relocation agreement. The department shall issue a permit, without any additional consideration, for any display that is being placed pursuant to a relocation agreement with another governmental entity if the relocated display conforms with the provisions of this section.

Interregional Road System Plan

A system of roads or projects on which construction can be started not later than June 30, 2000, that will provide the most adequate interregional road system to all economic centers in the state. The projects shall be on eligible routes identified and be located outside the boundaries of urbanized areas of over 50,000 population as designated by the most recent census of the Bureau of the Census, except as necessary to provide connections for continuation of the routes within those urban areas. [SHC Section 164.3]

According to the 2015 Interregional Transportation Strategic Plan, the Interregional Road System (IRRS) was first identified by statute in 1989 as part of the Blueprint Legislation (a ten-year transportation funding package that created by AB 471, SB 300, and AB 973). The IRRS, a subset of the 265 State Highway System (SHS) routes, provides connectivity between California’s major regions. There are currently 93 statutory IRRS routes, with many interstates among them. The IRRS was conceived as part of the larger effort to address the State’s critical transportation system funding and development needs. The implementation of IRRS improvements is dependent on prioritization of State transportation revenues. In addition, SB 45 requires that the Interregional Transportation Improvement Plan (ITIP) include a specific allocation of funds to be programmed on IRRS routes in non-urbanized areas.

Interregonal Road System

Blue Star Highways

After World War II, a nationwide movement was started to pay tribute to the nation's armed forces, by designatng various state and national routes as "Blue Star Memorial Highways". In 1945, the National Council of State Garden Clubs, Inc., approved the Blue Star Memorial Highway Marker program. California Garden Clubs, Inc. accepted the program in 1947, when the California Legislature designed US 40 (now I-80) and US 99.

For more information, see the Caltrans page on Blue Star Memorial Highways. Before July 1, 1964, there was a disconnect between the route numbers as signed on the highways, and the legislative route numbers. Thus, although a freeway might be signed as Interstate 5, it was LRN 238.

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