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California Roadway Departure 

Noteworthy Practices

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California Roadway Departure Safety Implementation Plan (RwDSIP)

Background 

California’s State Highway System (SHS) has approximately 15,100 center line miles. The California Department of Transportation 

(Caltrans) manages more than 50,000 lane miles of highways and freeways and is comprised of 12 districts. In 2012, the Federal 

Highway Administration (FHWA) developed the California Roadway Departure Safety Implementation Plan (RwDSIP) for Caltrans. 

The RwDSIP identified a total of 7,198 candidate locations for countermeasures using two different approaches: 1) a systematic 

approach and 2) a comprehensive approach. The systematic approach identified crash types that specific countermeasures were

designed to impact and selected clusters of locations where the targeted crashes exceeded the designated threshold, which varied

for each countermeasure. Roadway characteristics and traffic volumes also were considered in candidate location selection.

The comprehensive approach combined low-cost countermeasures with education and enforcement and was targeted to reduce 

severe roadway departure crashes on corridors and within municipalities that had a severe roadway departure crash history. These 

locations were on corridors with high concentrations of roadway departure crashes involving speeding or alcohol use. The 

designated thresholds varied based on the facility type (i.e., rural vs. urban, interstate vs. non-interstate). 

Figure 1: Implementation Summary of Identified Candidate Locations in the California RwDSIP

District staff field investigated 

each of the 7,198 candidate 

locations and determined the 

next steps for each location: 
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Challenges

It should be noted that the RwDSIP analysis did not include local roadway departure crashes since Caltrans only manages the SHS. 

Given that 61% of roadway departure crashes in California occur on local roadways outside of the SHS, the local agencies responsible 

would need to complete a separate analysis in order to address their local roadway departure crashes. A certain portion of 

California’s Highway Safety Improvement Program (HSIP) funds are used for projects on locally owned roads per Chapter 639, 

Section 182.85 of the California Streets and Highways Code. In addition, it should be noted that curve data was limited, so it was 

difficult to identify curve crashes and countermeasures specific to those types of crashes.

Caltrans noted several challenges with some of the recommended countermeasures. Utility pole relocation and tree removal were 

the two treatments with the greatest challenges. These countermeasure treatments were problematic for many Districts due to 

resistance from the public and the extra time needed to negotiate with the utility companies and to coordinate with other external 

agencies while managing other logistics such as right of way issues. In many cases, the Districts chose to shield the fixed object with 

guardrail. Tree removal was also problematic due to both removal challenges and the volume of trees.

Behavioral treatments (such as enforcement) were another challenge to implement due to the amount of interagency collaboration 

that was necessary. Therefore, Caltrans did not directly track this strategy as part of the RwDSIP and left it as an option to the 

Districts. The Districts became part of a task force to seek grant funding to implement speed and alcohol enforcement. However, this

has been handled as a separate process, which limits the direct control of enforcement or education outreach activities. 

High friction surface treatments (HFST) were already in use throughout California on roadway segments other than freeways. At the 

time, however, the countermeasure was still relatively new, so a lack of institutional knowledge became a challenge for site 

selection. Some candidate locations on freeway segments received pushback because the Division of Maintenance did not feel it was 

necessary across all travel lanes. Instead, Caltrans considered HFST for the outside lane where lane change maneuvers were more 

frequent. Additionally on freeways, the Districts did not want to implement HFST for short (i.e., one-half mile) sections and 

considered alternative treatments.

A procedural challenge was the ability to track countermeasure deployments. The large number of locations made it very difficult to 

utilize existing Caltrans tracking tools. Many Districts mitigated this obstacle by using standalone spreadsheets. 

Lessons Learned

There were several lessons learned through the RwDSIP process that should be considered in developing noteworthy practices.

There was an initial challenge of getting the Districts to “accept” the RwDSIP findings and recommendations and not feel the need to 

reevaluate or validate the findings. To combat this challenge, Caltrans directed the Districts to confirm whether the 

countermeasures could be implemented rather than spend time reviewing/validating the RwDSIP findings. 

In addition, many Districts were initially concerned about the limited staff resources available to perform mandatory field 

investigations. The Districts indicated that they relied on institutional knowledge to more effectively address the number of 

candidate locations in a timely manner. The Districts logged every candidate location from the RwDSIP into a database or 

spreadsheet tool, treated the investigation as a workload assignment, and tracked it as a status item at least every six months.

After the District investigations, Caltrans deemed more than 60% of the candidate locations from the RwDSIP as “No Action.” A 

candidate location was deemed as “No Action” if the treatment had already been installed or implemented, if the countermeasure 

was not considered cost effective (e.g., fixed object removal), or due to other site conditions such as traversing through a town or 

noise-sensitive area (e.g., for rumble strips). It should be noted that only observed crashes were used as the basis for the RwDSIP 

development. This analytical approach reflected the widely accepted “hot spot” methodology that was common at that time. 

In general, the Districts did not apply rumble strips on corridors with heavy bicycle traffic unless there was sufficiently wide 

shoulder. The Districts received some pushback from the bicycle communities, further emphasizing the need to be sensitive to the 

community when recommending and implementing countermeasures.
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Success Stories

Caltrans noted several overall success stories directly or indirectly from the RwDSIP process. Overall, center line and edge line 

rumble strips were the most applied countermeasure across the state. There were already several center line and shoulder rumble 

strip deployments in place/ programmed prior to the RwDSIP, 

but the RwDSIP further increased deployment. Caltrans also 

noted that its existing monitoring list for cross-center line 

crashes has been getting smaller, indicating that these types 

of crashes are trending with a drop in overall frequency.

District 3 had the most available before/after data for comparison purposes. Prior 

to the field investigations, District 3 had 886 candidate locations from the RwDSIP. 

The majority of these were rumble strips, while others included tree removal, 

alignment delineation and lighting, HFST, and alcohol/speed enforcement. As a 

result of the field investigations, District 3 designated 105 new project locations 

consisting of a single site and 52 new project locations consisting of multiple sites

and deemed approximately 50% of the candidate locations as “No Action.” After 

implementation of these projects, District 3 saw a reduction in crashes. As a result 

of the RwDSIP, District 3 has been viewing treatments in a more systemic/

proactive fashion as opposed to being reactive at isolated locations.

Shaping of Standards, Policies, and Practices

The RwDSIP has influenced Caltrans to augment several existing or developing standards, policies, and practices as follows:

• Caltrans has recently established a policy/standard requiring 6-inch wide striped edge lines and center lines.

• Caltrans has incorporated rumble strips as a standard treatment with new projects, in addition to proactive efforts based 

on traffic volume.

• Standard plans and guidance already existed for guardrail, but the RwDSIP provided a thorough, systematic approach to 

implementing treatments.

• Caltrans initiated a policy 4-5 years ago to improve sign retroreflectivity. With all “major” projects, every sign panel within 

the study area will be replaced and upgraded to current standards.

• Caltrans has been working with the Division of Maintenance to improve pavement marking retro-reflectivity and potentially 

advance to a future policy or guidance.

In addition, the RwDSIP delivered by FHWA for Caltrans has influenced how Districts approach new sites and locations with low-cost 

treatments, both systemically and at isolated locations.

For Additional Information

For additional information about the FHWA Roadway Departure Focus State Initiative, contact Joseph Cheung, FHWA Office of 

Safety, at joseph.cheung@dot.gov.

For additional information about the California Department of Transportation, contact Robert Peterson, California Department of 

Transportation, at robert.peterson@dot.ca.gov.

Publication Number FHWA-SA-20-024

Figure 2: Caltrans District 3

Caltrans District 3 is responsible 

for maintaining and operating 

1,491 center-line miles and 4,385 

lane miles in 11 Sacramento Valley 

and Northern Sierra counties.