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APPENDIX E Key Traffic Incident Definitions Traffic incidents are all too common in the transportation world. As stated in the 2010 Guide, these are the more frequent challenges to state transportation agencies and their public safety-- and other responder--colleagues. With the exception for minor traffic incidents, they are subject to National Incident Management System requirements. This appendix discusses two facets of traf- fic incidents, (1) the level of incident, and (2) the timeline of an incident. Incident Level The MUTCD defines three levels of incidents--minor, moderate, and major, sometimes referred to as levels 1, 2, and 3, respectively. Table E.1 summarizes the characteristics of these. To distinguish these from emergency-type incidents, the 2010 Guide refers to these as traffic inci- dents. It is important to understand that a major traffic incident could become a major incident in the EM manner, for example, the reduced-visibility major incident on I4 in Florida. Incident Timeline 27 Figure E.1 illustrates the timeline of a typical incident that might be a crash affecting one or more travel lanes. Not all of these steps might occur in a particular incident, and there may be other interwoven relationships, but this represents the typical sequence for most moderate to serious incidents. The steps are shown in a staggered fashion simply to illustrate that the inci- dent timeline is not uniform; however, the time increments are purely relative. In the discussions below, the duration of particular events will be noted as letter pairs. For example, the actual inci- dent duration would be AM, as shown in Figure E.1(a), while the total influence time of the incident is AN, as shown in Figure E.1(b). The durations of the common phases of an incident would thus be as follows: Detection that an incident has occurred: AB; Verification that the incident has occurred, determining its location, and having sufficient information to enable an appropriate response: BC; Response by dispatching appropriate assets to resolve the incident: CE; 27 This subsection was adapted using almost the same text from the TIM/Quick Clearance Toolkit, by the same principal author. (I-95CC, 2009) 150

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Key Traffic Incident Definitions 151 Table E.1. Traffic incident characteristics. Level MUTCD Duration Common Cause Frequency Minor (1) < hour Fender bender, Many per day disablement, debris Moderate (2) to 2 hours Single vehicle Many per week crash, minor spills Major (3) > 2 hours Collisions, injuries, Occasional fatalities, large spills Source: Adapted from NCHRP Report 525, Volume 6, 2005 Source: (I-95CC, 2009) Figure E.1. Typical traffic incident timeline.

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152 A Guide to Emergency Response Planning at State Transportation Agencies Clearance, or the removal of the vehicles, damaged property, and victims from the incident scene, and complete reopening of any blocked lanes: EM (with roadway clearance as a sub- set, EK); and Recovery to normal traffic flow: MN. The actual time of an incident is generally difficult to determine with certainty, so durations are generally started with initial notification, or point B. In terms of actual duration, the recovery time (the difference between the total incident influence time and the actual duration) can be 45 times longer than the incident duration itself. Note that at points D and E, the first responder has not been explicitly identified. This is often law enforcement; however, in areas with service patrols, it is often the latter, and law enforcement would be one of the secondary responders (in time, not importance). Further, this graphic presumes a sufficiently serious incident and that a full range of incident management services will be required, almost certainly law enforcement; possibly fire rescue, emer- gency medical, and hazardous material handling; and wrecker(s). Thus, it likely represents a mod- erate or major traffic incident. Minor traffic incidents generally do not require most of these responses and services.