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Crash Data Collection and Use

Introduction  What is Crash Data  Additional Information 

What is Crash Data?

Crash data is traffic accident information recorded by various police agencies throughout the State. The collected data is used as a tool by highway safety professionals to determine why specific accident patterns are occurring and how highway safety needs can be addressed.

Are all vehicle crashes that occur reported?

No! Crashes resulting in a personal injury or fatality are reported by law enforcement agencies. Crashes that result in property damage typically are only reported if one of the vehicles involved must be towed away, or if a driver committed a serious offense, such as drunk driving.

How is crash data collected and processed?

Crash data is recorded by the state, county, local or federal law enforcement officer at the scene of the reportable accident. Later, the data may be reviewed and edited. Typically, within 10 days of the accident occurrence, the report is submitted to the Maryland State Police Central Records Division for transfer into the Maryland Automated Accident Reporting System (MAARS) database file; within 30 days, the data is uploaded to the Maryland State Highway Administration's database.

State and local traffic safety officials strive to minimize the number and severity of crashes by applying the Three E’s - Engineering, Education, and Enforcement. The Traffic Safety Analysis Division (TSAD) in the SHA Office of Traffic and Safety is the lead organization for these efforts, combining its engineering expertise with the public education resources of the Maryland Highway Safety Office, and the enforcement powers of the State Police and other law enforcement agencies.

Does a high number of crashes mean that a location is hazardous?

No! The number of crashes alone does not necessarily indicate a hazardous condition. It is important to compute accident rates, which take into account traffic exposure. Rates are based on the number of vehicles entering an intersection or the vehicle-miles of travel along a specific section of a highway. The accident rates for a particular location then can be compared to statewide average rates for similar locations. SHA's brochure Crash Data Analysis explains how accident rates are calculated, evaluated and used.

Why is it important to collect and analyze crash data?

Millions of dollars are annually spent to make our highways safe and efficient. Most safety improvements result from analyzing accident information at specific locations. It is essential, therefore, that crash information is accurate; otherwise, measures could be implemented that would be ineffective or even could make the situation worse.

Based on the crash patterns, SHA and local jurisdictions are able to determine the nature of the problem and develop the proper solution to reduce crashes. After improvements are complete, crash data is again analyzed to determine their effectiveness. The modern roundabout, shown in the photograph at right, is an example of a relatively new type of safety improvement proven effective in reducing angle, left-turn and opposite-direction crashes.

Modern Roundabout
Intersection Safety Improvement Modern Roundabout

What types of crash data reports does SHA produce and how are they used?

SHA produces a wide variety of accident summaries and reports, such as collision diagrams (see sample below), statistical reports, program reports (e.g., an annual Highway Safety Improvement Program report), and historical crash trend reports. Crash data also is used to guide and direct federally and state funded safety programs, such as SHA's Traffic Control Devices Program, and Safety and Spot Improvement Program (report cover shown inside this brochure). The Traffic Safety Analysis Division also conducts crash data analyses for other state and local agencies for their independent safety studies.


Sample Collision Diagram
How are other agencies using crash data?
The Maryland Motor Vehicle Administration (MVA) has created a graduated licensing program to help reduce crashes involving inexperienced drivers. Statistically, these drivers had been found to be involved in more crashes than the rest of the driving population.

SHA's Office of Planning and Preliminary Engineering considers accident patterns during project planning studies and environmental evaluations.

SHA's Office of Highway Development uses crash data to guide the design of highway improvements.

SHA’s District Offices use crash data for traffic safety and operations studies and improvements.

The Maryland State Police and local enforcement agencies select sites for sobriety checkpoints based on the locations of alcohol-involved crashes.
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