Engineering
When a traffic safety issue is identified, changing the roadway—including traffic signals, signage, or the like—may appear to be the most direct solution. However, a close look at crash data and driver behavior often reveals that engineering is just one component of a complete traffic safety solution—a solution that includes education, enforcement, and emergency services.
Local and State Traffic Engineers
Building a relationship with your county or city engineering staff is the most important step in resolving questions about engineering and roadway safety. Ensuring safety is one of the primary responsibilities of public works engineers, and their training gives them the tools to evaluate safety issues and recommend effective solutions.
In addition to county and city engineers, your Minnesota Department of Transportation (Mn/DOT) district office is also an excellent resource. Mn/DOT works with county and city engineers on many road construction projects and oversees large projects on major state and federal highways (see Road Safety Audit, below).
Examples of Engineering Efforts
Engineering changes to improve safety and mobility can range from simple road striping improvements to the complete reconstruction of entire highway corridors. Some examples include:
- Improving intersection signs
- Upgrading pavement markings for better visibility in all weather conditions
- Installating street lights at intersections
- Changing the vertical alignment (grade) of intersections
- Upgrading guard rails to accommodate higher vehicle speeds
Road Safety Audit
The Minnesota Departments of Transportation and Public Safety have developed a road safety audit (RSA) procedure to evaluate safety issues on major road corridors. The goal of an RSA is to reduce crashes using methods that can be implemented quickly, in accordance with overall plans for a traffic corridor.
An RSA is carried out by a multi-disciplinary team of engineers and public safety specialists who meet with community representatives and local engineering staff before starting their investigation.
Following is an excerpt from a road safety audit of Highway 52 in Minnesota:
"Based on a review of crash data and a field review of the corridor, it appears that the biggest issues contributing to crashes are minor street crossing maneuvers combined with the lack of gaps in the traffic stream on Highway 52 and high vehicle speeds (especially during adverse weather conditions). However, multiple causes of crashes were noted – suggesting that a coordinated Engineering/ Enforcement/Education/Emergency Services approach is required to address safety along Highway 52."
Traffic Calming
The term "traffic calming" is often applied to any physical changes to the roadway intended to reduce speeds or promote safety for pedestrians and other nonmotorized road users. However, traffic calming can also include a variety of strategies for educating drivers and making people aware of unsafe driving behavior.
Traffic calming solutions must be tailored to the situation in order to be effective. Matching engineering changes with appropriate public education and enforcement efforts will make a traffic calming project much more likely to succeed.
Traffic calming is often associated with context sensitive design – a set of principles that helps engineers reach the most appropriate design decision for a specific location or set of circumstances.
Rural Road Safety Solutions
Minnesota's Local Road Research Board (LRRB) and Mn/DOT's Division of State Aid for Local Transportation developed Rural Road Safety Solutions for local agencies. A key message of the training was about the safety "revolution" afoot in Minnesota, whereby those responsible for roadways are asked to focus on low-cost prevention strategies that address traffic fatalities and serious injuries, rather than simply looking at overall crash rates.
Eight workshops were presented throughout the state by a team that included the FHWA safety engineer for Minnesota, the Mn/DOT state traffic safety engineer, three county engineers, and the consultant who developed the curricula. Attendees left with an understanding of the many tools and technologies available for the assessment and improvement of rural roads. The workshops also provided information about highway safety trends at the national, state, and local levels; specific engineering strategies to improve safety; and funding and how to garner support for safety-related projects.
Resources and Links
Minnesota Department of Transportation – Office of Traffic, Safety and Technology
Rural Highway Safety Clearinghouse - Engineering section
Minnesota Department of Transportation Traffic Safety Fundamentals Handbook 2008 (PDF)
Summarizes key facts and characteristics of traffic safety on Minnesota's roads and highways.
Traffic Calming in Minnesota is a Web site developed for the Minnesota Local Road Research Board (LRRB) containing a searchable database of traffic calming projects implemented in Minnesota and traffic calming data collection guidelines.
Federal Highway Administration: Traffic Calming contains a collection of techniques for reducing the negative effects of motor vehicle use.
Context Sensitive Design (CSD) is a U of M Center for Transportation Studies page on Mn/DOT's CSD initiative.
Minnesota Crash Mapping Analysis Tool is a graphical application that enables users to analyze crash data based on a number of attributes, including county, city and accident case number.
Roundabouts in Minnesota
Minnesota Department of Transportation