Case Study:Rural Intelligent Transportation Systems & Mapped Collision Data

Safety in Rural Northern California

The rural portions of the greater Sacramento region are diverse. They include the Sierra Nevada, farming areas of the Sacramento Valley, ranchlands, parkland and recreation areas, and many small towns. This area’s highways and roads serve residents, visitors, and through traffic. The less urban areas of the region continue to face safety challenges on their major roads and highways. Nationwide, rural areas account for 55% of all traffic fatalities despite having only 23% of the population. State and local statistics largely reflect the national trends. See Figure 1 for more details.

In the six-county greater Sacramento planning area, 89% of the land is in non-urbanized zones. Historically, these areas lag behind the urban areas in resource investment despite having 48% of the road miles. Yet the economic and social fabrics of rural areas are inextricably linked to those of the nearby urban centers.

Rural-Urban Connections Strategy

SACOG is engaged in a new planning initiative, the Rural-Urban Connections Strategy (RUCS). RUCS is exploring the existing conditions and emergent issues of the less urbanized portions of the region, and is looking to build consensus around opportunities and innovations to address rural challenges. Safety is an important topic in this regional conversation. Intelligent transportation system (ITS) applications and the use of geographic information systems (GIS) offer promising, cost-effective solutions to rural road safety issues.

Collision Data

Accurate, spatially referenced collision data can help local governments better define the extent and nature of their roadway safety needs. Roadway collisions have been digitized into a GIS and mapped to assist regional strategies to reduce roadway injuries and fatalities. These data can assist local governments with the analysis of collision clusters and other geographic patterns by providing justification for state safety investigations or as ancillary data support for integrated safety studies.

The National Highway Traffic Safety Administration coordinates the collection of collision data throughout the nation, with the California Highway Patrol (CHP) leading this effort in the State of California. CHP gathers mandated collision reports from law enforcement agencies throughout the state and enters this information into a central database named the Statewide Integrated Traffic Records System (SWITRS). Information on the collisions includes severity, type of vehicle, estimated speed, number of vehicles and persons involved, location, and others. But the standard reports from SWITRS tend to be broad and aggregated, not always useful for facility-level analysis. Individual collision reports give no insights into trends or tendencies. Spatial analysis with GIS is an important complement to other analysis tools and methods for phenomena that are arrayed onto the landscape.

SACOG has populated a GIS database with SWITRS collision reports for five years (2002-2006) and across six counties. Raw data in SWITRS are provided as text files with many data attributes, including a location description for each record. Technicians used a combination of software algorithms and state milepost data to geo-code collision locations to the nearest road intersection. Almost 96% of all fatality or injury collisions were successfully geo-coded for El Dorado County. Figure 2 provides an example of collision data presented in a GIS. Collision data for all six counties in the SACOG planning area are being compiled into a GIS for further analysis.

Rural ITS

Intelligent transportation systems have many potentially valuable applications in rural transportation. Perhaps because of the emphasis on information technology or perceived cost, ITS are often overlooked as an option in the toolbox for rural safety solutions. But in fact, there are number of proven, effective applications:

• Emergency Services – Includes services provided by law enforcement, fire departments, emergency medical services, and related organizations. An example is the satellite positioning technology integrated into communications for a great number of rural first responders.
• Traveler Information – Provides information such as weather conditions, route advisories, and information on road closures. Examples include SAFE Passage in Bozeman, MT, and the 511 System in the SACOG region.
• Traffic Management – Improves operations on rural highways; technologies include traffic control, in-vehicle route guidance, variable message signs, and rural transit coordination/operations. An example is Oregon’s Trip Check travel information website.
• Crash Prevention – Help drivers avoid crashes and reduce their crash severity by implementing mayday systems, road weather information systems, highway advisories, emergency vehicle preemption, and animal detection/deterrence. Examples include Denver’s Dynamic Downhill Warning System, and the California Dynamic Speed Warning System.

Determining which ITS strategy is most appropriate for a given rural safety issue involves data collection, complex analysis, and careful planning. The following case study illustrates these principles in action.

Case Study: El Dorado County Employs Rural ITS Solution

El Dorado County is a fast growing, vibrant part of the Sierra Nevada which includes many miles of rural highways. Containing South Lake Tahoe, historic mining towns, and a thriving forestry, orchard and viniculture sector, El Dorado is an important destination for many Californians and out-of-state tourists. With visitors and commerce also come increased traffic and its associated safety issues.

In partnership with the State of California, El Dorado County has won a grant from the United States Department of Transportation’s (USDOT) Rural Safety Innovation Program entitled “Intersection Safety Using ITS Technology.” This exciting opportunity will allow the County to implement a new ITS application in a high risk rural location, where collision rates at the uncontrolled, un-signalized intersection are significantly higher than state averages. The application is called a Collision Countermeasure System (CCS). The implementation of the CCS will also serve as a Caltrans ITS demonstration project.

The project site is located in the Camino community area along U.S. Highway 50, at its intersection with Still Meadows Road. The local road provides access to about 25 residences, and a busy restaurant located at the intersection. This location has a history of side impact vehicle collisions, often resulting in injury and even death. Between 2002 and 2007, the collision rate was .44, twice the state average for intersections of similar characteristics. Over this period there were 11 injuries and one fatality. Average daily traffic in the project area was about 26,000 in 2006, and travel models forecast this to increase to 38,000 by 2019.

The CCS will be designed to reduce side impact accidents at U.S. 50 and Still Meadow Road by warning drivers of conflicting cross traffic. The project will install the following ITS infrastructure:

• Vehicle detection pavement loops on Still Meadows near the highway to detect the actual presence of approaching traffic.
• “Type 1” Active Signs on the U.S. 50 approaches from both directions, flashing a static message “cross traffic ahead”.
• “Type 2” Dynamic Message Signs that will advise drivers in both directions the real-time presence of approaching traffic on the cross street.

Based upon the 65 miles per hour speed limit on U.S. 50 and accident prevention analyses, the Type 1 signs will be located approximately 650 feet from the intersection. The Type 2 signs will be located 350 feet from the intersection. Sufficient infrastructure presently exists in the project area to support the power and communications requirements of the technology. Collision data will be collected for three years to analyze and measure the effectiveness of the CCS.

Opportunities and Innovations

Some additional programs that may provide opportunities for ITS and data driven innovations include:

• National ITS Program Plan – Under SAFETEA-LU, $110 million has been set aside for a broad range of research and development.
• ITS Deployment Funding – Mainstreamed throughout the Federal-aid programs; ITS projects are eligible for funding under NHS, STP, and CMAQ; ITS projects have a categorical NEPA exclusion.
• Sacramento Transportation Area Network (STARNET) – A regional ITS program with an established Regional Architecture, now in systems engineering prior to a major infrastructure investment; mainstreaming rural ITS plans and projects through STARNET may convey an advantage to independent grant applications and may allow these programs greater opportunities for regional funding.
• Rural Transit ITS – Providing critical transit services to rural residents has many resource challenges, but ITS can help design creative and cost-effective solutions for delivering services; an excellent source on this topic is “Rural Transit ITS Best Practices” by FHWA (March 2003).

Data and technology can work hand-in-hand to provide cost-effective safety solutions in rural areas and deliver the maximum benefits to the region’s citizens. Because the rural parts of the region are prone to higher accident rates and lag behind the urban centers in capital investment, creative approaches are required to adequately address roadway safety challenges. The RUCS planning efforts are dedicated to working with rural and small urban stakeholders in identifying the most promising opportunities and to focus efforts on acquiring additional resources.

References

“Post-mile Service”, Office of GIS, Transportation System Information, Department of Transportation, State of California.

“Statewide Integrated Traffic Records System”, Information Services Unit, Support Services Section, California Highway Patrol.

“California Strategic Highway Safety Plan”, CALTRANS; California Business, Transportation, and Housing Agency; 2006.

“2006 Traffic Safety Facts”, National Highway Traffic Safety Administration, National Center for Statistics and Analysis, U.S. Department of Transportation.

El Dorado County Transportation Commission, Rural Safety Innovation Program, Phase II Grant Application, “U.S. 50 – Still Meadows Road Intersection”, 2008.

“Intelligent Transportation Systems Strategic Deployment Plan for the Sacramento Region”, SACOG, September 2005.