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Pages 6-24

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From page 6...
... 6 The Language of Traffic Incident Management Using common terminology and definitions when describing TIM­related activities is the first step toward uniform and consistent evaluation of TIM programs within and between agencies. This chapter presents considerations to encourage uniform use of terminology that is foundational to TIM and the evaluation of TIM programs.
From page 7...
... The Language of Trafc Incident Management 7   involved vehicles, number of lanes blocked, and whether primary or secondary. Other information oen collected includes: • Weather, light, and other environmental conditions.
From page 8...
... 8 Guidelines for Quantifying Benefits of Traffic Incident Management Strategies system because it is simple to apply and because time correlates with incident severity and number of secondary incidents (Karlaftis et al., 1999; Hirunyanitiwattana and Mattingly, 2006; Khattak et al., 2011)
From page 9...
... The Language of Traffic Incident Management 9   entry processes. The routine, organized recording of incident timestamps is necessary to compute TIM performance measures.
From page 10...
... 10 Guidelines for Quantifying Benefits of Traffic Incident Management Strategies Roadway Clearance Time RCT is one of the three TIM program performance measures identified by FHWA and is the period between the first recordable awareness of the incident by a responsible agency and the first confirmation that all lanes are available for traffic flow (Conklin et al., 2013)
From page 11...
... The Language of Traffic Incident Management 11   miles upstream of the incident and may include multiple facilities. Consequently, the time duration to return to normal flow requires estimation.
From page 12...
... 12 Guidelines for Quantifying Benefits of Traffic Incident Management Strategies According to analyses of incidents conducted across three regions in the development of this guide, the percentage of incidents that were prevented by implementing TIM programs ranged from 2.6% to 7.2%. This range reflects the application of three different methods for estimating the reduction in secondary incidents across three regions (North Dallas, Texas; Capital Beltway, Maryland; Seattle, Washington)
From page 13...
... The Language of Traffic Incident Management 13   Significant literature highlights best practices for TIM activities, including the TIM Handbook (Owens et al., 2010) , Best Practices in TIM (Carson, 2010)
From page 14...
... 14 Guidelines for Quantifying Benefits of Traffic Incident Management Strategies resource utilization, and performance measurement. More on cost recovery can be found in Rensel et al., 2012.
From page 15...
... The Language of Traffic Incident Management 15   The common thread in evaluating the different types of outcomes is the need for data. All outcomes can be quantified, and some outcomes can be monetized.
From page 16...
... 16 Guidelines for Quantifying Benefits of Traffic Incident Management Strategies incidents less than 57 minutes, resulting in 662,000 gallons of fuel savings. This fuel savings translates to 270.4 tons of CO, 5.2 tons of HC, and 14.7 tons of NOx (Minnesota DOT, 2004)
From page 17...
... The Language of Traffic Incident Management 17   • Existing Tools -- Some tools are available to quantify one or multiple outcomes. These tools offer an effective means to derive more precise estimates than spreadsheet or rule of thumb tools without requiring advanced mathematical, statistical, or simulation expertise.
From page 18...
... 18 Guidelines for Quantifying Benefits of Traffic Incident Management Strategies PARAMICS, VISSIM, and CORSIM are three commercially available simulation tools that have been applied to quantify delay and emissions outcomes from TIM activities. Many TIM programs have invested in the conduct of simulation models to derive measures of delay and other metrics.
From page 19...
... The Language of Traffic Incident Management 19   (NC DOT)
From page 20...
... 20 Guidelines for Quantifying Benefits of Traffic Incident Management Strategies The other commonly assessed environmental measure that is included in TIM benefits analysis is fuel consumption. Recognizing the environmental and economic impact of fuel consumption, many researchers and government agencies have developed complex models for high­resolution estimates of fuel consumption in the transportation sector.
From page 21...
... The Language of Traffic Incident Management 21   The second item is defining a relationship between reduction in incident duration and the reduction in the number of secondary incidents from TIM activities. The simplest method is to apply the same reduction in the percentage of ICT to the reduction in secondary incidents, that is, a reduction in incident duration of 25% equates to a 25% reduction in secondary inci­ dents.
From page 22...
... 22 Guidelines for Quantifying Benefits of Traffic Incident Management Strategies analysis is not feasible for identifying secondary incidents. This percentage is likely even lower for regions that do not experience heavy congestion.
From page 23...
... The Language of Traffic Incident Management 23   • By reducing the number of incidents and the duration of exposure, the probability will decrease accordingly. This is computed as 0.00096 × (1 – % reduction in incidents)
From page 24...
... 24 Guidelines for Quantifying Benefits of Traffic Incident Management Strategies How to Monetize TIM Outcomes? Monetization is applying financial values to quantified outcomes.

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