6 minute read
Roadway safety data and public works: it’s fundamental
Stephen W. Read, P.Eng., Highway Safety Improvement Programs Manager, Virginia Department of Transportation, Richmond, Virginia; Michael B. Sawyer, P.E., Senior Highway Safety Engineer, Vanasse Hangen Brustlin, Inc., Richmond, Virginia
ccording to a recent American Automobile Association (AAA) study, the cost of motor vehicle crashes in urbanized areas was close to $300 billion in 2009. For the same year, a Texas Transportation Institute (TTI) congestion study for those same urban areas pegged the cost of congestion at nearly $100 billion. Practicing professional engineers go to work every day to assist planners, city managers and other public works professionals in their local communities to stay focused on safety and to deliver crucial countermeasures to address severe crashes.
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Innovative solutions and unique approaches are used to save lives and prevent serious injuries from motor vehicle crashes. Public works agencies and professionals are also tasked with any variety of roles related to roadways safety—from planning to operation and maintenance. Using roadway safety data can help inform local decision-making processes and make policy and program decisions for roadway safety improvements.
In the past, an engineer would start with a traffic crash database to find concentrations of severe crashes. Now, with the use of roadway inventory data, engineers are pushing to expand how they determine where their low cost, systemic safety countermeasures would be most effective within the jurisdiction for which they are responsible. This more robust approach reflects a renewed emphasis on improving and combining roadway inventory data with crash data. These combinations include looking at dangerous horizontal curves, as well as critical intersection or facility types. Recent research demonstrates that a small subset of the roadway inventory can be extremely effective when combined with related crash data.
Having an extensive understanding of the existing conditions is preferred, but starting with some basic roadway inventory data can provide a better focus to save lives. Increasingly, the Fundamental Data Elements (FDE) shown below are being used to save lives in communities across the country, yet some engineers and public works professionals may not have heard about how powerful a “small” amount of information can be.
So how can transportation agencies use these FDE with the Highway Safety Manual (HSM) or SafetyAnalyst to save lives?
The Virginia Experience
Like other transportation agencies, the Commonwealth of Virginia is on a journey towards zero deaths. Over the past five years, Virginia has
Segment ID* Intersection ID Route Name* Location Alternate Route Name* Intersection Type Route Type* Date Opened to Traffic Area Type* Traffic Control Type Date Opened to Traffic Major Road AADT Start Location* Major Road AADT Year End Location* Minor Road AADT Segment Length* Minor Road AADT Year Segment Direction Intersection Leg ID Roadway Class* Leg Type Median Type Leg Segment ID Access Control* Ramp/Interchange Two-Way vs. One-Way Operation* RampID* Number of Through Lanes* Date Opened to Traffic Start Location
Interchange Influence Area on Mainline Freeway Ramp Type
AADT* Ramp/Interchange Configuration Ramp Length AADT Year* Ramp AADT* Ramp AADT Year
*Highway Performance Monitoring System full extent elements are required on all Federal-aid highways and ramps located within the grade-separated interchanges, i.e., National Highway System (NHS) and all functional systems excluding rural minor collectors and locals.
Twelve of the 38 Fundamental Data Elements (FDE) recommended for collection are intersection data.
made significant strides in becoming a leader in safety performance by reducing annual deaths and injuries.
Just seven years ago, Virginia was safety data rich, but information poor. In 2005, the National Highway Traffic Safety Administration (NHTSA) provided a less than favorable assessment of Virginia’s data systems, highlighting the need to update the current crash system and related processes. Many of the safety data streams existed; however, they were not connected and only a few talented data analysts could shape safety data into a picture that could drive and engage the involved safety partners in Virginia.
The Virginia Department of Transportation (VDOT) initially became involved in SafetyAnalyst software development in 2003, and is now one of its biggest supporters. SafetyAnalyst, an AASHTOWare product, incorporates the HSM safety management process into a computerized analytical tool for better decision-making for identifying safety challenges and developing a set of improvement projects. The transportation agency created a Strategic Highway Safety Plan (SHSP) in 2005 to upgrade the roadway inventory through its asset management practice to match its noteworthy traffic volume count program.
In 2009, VDOT made the decision to take a step forward in crash data analysis by becoming one of the lead states to adopt SafetyAnalyst. However, Virginia’s data system was not set up to use this tool to its fullest. Notably, Virginia was in the middle of transforming its roadway inventory system to improve the interoperability of crash data with roadway inventory data in a geographic information system (GIS) platform.
While the new GIS-based system was under development to address the SHSP emphasis areas, VDOT safety engineers used the known elements for segments and intersections to develop ranked listings for each jurisdiction of roadway departure and intersection-related crashes and people-injured locations. The listing and generated maps have helped focus on safety improvements. Additionally, VDOT collected additional roadside highway and traffic control data to improve asset management and budgeting. Using the same geospatial data, VDOT recently obtained the highway horizontal and vertical alignment on the major statemaintained roads. Alignment data will be helpful for planning safety improvements and scoping design projects.
Virginia has now substantially upgraded its roadway inventory and is launching the implementation of the HSM into its safety programs and project designs. The initial outcomes of linking the FDE to crash data have been very positive.
The HSM introduces a science-based technical approach that takes the guesswork out of safety analysis. More than 140 VDOT planners, engineers and technicians received training with a comprehensive HSM overview. The HSM provides the methods to conduct quantitative safety analyses, allowing safety to be quantitatively evaluated alongside other transportation performance measures such as traffic operations, environmental impacts and construction costs.
Eight of the 38 Fundamental Data Elements (FDE) recommended for collection are ramp and interchange data.
Project engineers are starting to use the methods during the design phase. For project planning, several science-based safety performance functions for SafetyAnalyst were calibrated for Virginia’s roadways during the systems development period. With the ongoing translation of the improved data elements into SafetyAnalyst, Virginia will have another tool to leverage with existing safety programs to assist its engineers to find the best sites to deploy countermeasures.
Although Virginia is now one of the states at the forefront of safety analysis with the deployment of SafetyAnalyst, there are still improvements needed on collecting and maintaining data for Virginia to leverage advanced capabilities. In Virginia, SafetyAnalyst will become fully functional and integrated into the Highway Safety Improvement Program (HSIP) process. However, this is not a capstone for Virginia or any other state working to improve its safety data capability. Using new methods and tools are milestones on a journey for people who are using FDE and improving relationships between the highway network and crashes to save lives.
This is just one example of how a state is using roadway safety data to inform their safety decisions, and how that investment is saving lives. Do you know what roadway safety data are being collected in your community? Remember, “small” can indeed be powerful. For more information on Virginia’s experience, please contact Stephen Read at Stephen.Read@vdot.virginia.gov. Additional SafetyAnalyst information is available at www.safetyanalyst.org.
For clarifications or verifications, Mike Sawyer can be reached at (804) 343-7100. Stephen Read can be contacted at (804) 786-9094.
