By Richard J. Ashton, Chief of Police (Retired), Frederick, Maryland; and Grant/Technical Management Manager, IACP
n a perfect world, we could drive from here to there in the actual time required to do so at lawful speeds and in obedience to traffic control signals. However, every commuter knows that we do not live in a perfect world. Drivers and passengers who typically traveled during peak periods in 439 U.S. urban areas spent 34 additional hours in 2010—20 more than in 1982—traveling at congested speeds rather than at free-flow speeds. Further, they wasted 14 gallons of fuel in 2010—8 gallons more than in 1982. The time lost equated to four vacation days and, when coupled with wasted fuel, translated for the average commuter into an expense of $713 in 2010 compared to an inflation-adjusted $301 in 1982.1
Aside from the obvious frustration that traffic incidents evoke in highway users, traffic incidents cause about one-quarter of the congestion on U.S. roadways, and, for every minute a freeway lane is blocked by an incident, four minutes’ travel delay time results.2
An incident is defined in the Traffic Management Data Dictionary, published by the Institute of Transportation Engineers and the American Association of State Highway and Transportation Officials, as “an unplanned randomly occurring traffic event that adversely effects normal traffic operations.”3 It is the nucleus of congestion by which law enforcement and other public safety disciplines are challenged across the United States myriad times every day. To the degree that law enforcement and other disciplines effectively, efficiently, and safely prepare for—and respond to—the primary incident, congestion, as well as the frequency and seriousness of secondary crashes, will be reduced.
A secondary crash is an unplanned event—beginning at the time the primary incident is detected—where a collision that results from the original incident occurs either within the incident scene or within the queue, including in the opposite direction. The likelihood of a secondary crash increases by 2.8 percent for every minute that the primary incident remains a hazard, and secondary crashes alone are responsible for an estimated 18 percent of all freeway fatalities and 20 percent of all collisions.4
Traffic incidents are classified, by virtue of their anticipated duration, into three categories:
- major—those incidents that are expected to last in excess of two hours;
- intermediate—those that are projected to last between 30 minutes and 2 hours; and
- minor—those incidents that are expected to last fewer than 30 minutes.5
Realistically, the bulk of the incidents with which law enforcement deals are the minor ones, such as debris in the roadway, disabled vehicles, fender-bender crashes, and traffic stops. They generally are resolved by a police officer, a tow truck, or a public works vehicle and primarily are of interest only to those directly involved.
However, the traffic incidents that cause the greatest consternation are the major ones, such as crashes involving multiple fatalities or hazmat spills. They often result in lengthy road closures or detours. While they tend to be few and far between, they never are forgotten when they are mishandled—that is, when those delayed by such incidents are late for business meetings, medical appointments, picking up their children from day care providers, long-awaited flights to vacation destinations, or cheering on their children at soccer matches.
Traffic incident management (TIM) is “a planned and coordinated multidisciplinary process to detect, respond to, and clear traffic incidents so that traffic flow may be restored as safely and quickly as possible.”6 Consequently, it is the key to reducing the incidence and the severity of crashes and the congestion and the frustration they create. The three fundamental principles upon which TIM is based—responder safety; safe, quick incident clearance; and prompt, reliable, interoperable communications—are embodied in the National Unified Goal (NUG),7 which the IACP has supported since 20078 a