Guidelines for Quantifying Benefits of Traffic Incident Management Strategies (2022) / Chapter Skim
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Pages 54-65
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From page 54... ...
54 Application and Assessment of FHWA TIM Benefit-Cost Tool The final publishing of the FHWA TIM Benefit-Cost Tool presented an opportunity for comparison with other TIM methods. This tool has six independent modules that allow users to prepare a BCA for eight TIM activities: 1.
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Application and Assessment of FHWA TIM Bene t-Cost Tool 55 D.2.1 Roadway Geometry Inputs are the same across all eight TIM activities: roadway geometry, including the number of lanes, general terrain, horizontal curvature, and the number of ramps (Figure D2)
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56 Guidelines for Quantifying Bene ts of Traf c Incident Management Strategies are requested for each operation time selected in the "Program Information" input, which is presented in Part D.2.4. Tra c volume input ranges from 500 to 2,200 vehicles per hour per lane.
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Application and Assessment of FHWA TIM Bene t-Cost Tool 57 facility closures are considered, nor when more than four lanes are blocked on a six-lane or greater facility. e speci cation of incident duration and the count is based on the presence of the TIM strategy to be assessed.
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58 Guidelines for Quantifying Bene ts of Traf c Incident Management Strategies Figure D5. TIM-BC SSP program information: two incident duration savings options.
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Application and Assessment of FHWA TIM Bene t-Cost Tool 59 D.3 Applying FHWA TIM-BC Tool, SSP Module to Maryland Data As a part of the analyses of multiple methods in this research to estimate the delay, emissions, and secondary incident bene ts from TIM, data from Maryland, Seattle, and Texas were explored. e Maryland data, which included 1,130 incidents over 3 months, were processed and subsequently applied within the SSP module of the TIM-BC tool.
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60 Guidelines for Quantifying Bene ts of Traf c Incident Management Strategies screenshot of the project details, including name, segment, study duration, and annual costs. An estimate of $12 million in annual operating cost is input as the total Maryland CHART's TIM costs.
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Application and Assessment of FHWA TIM Bene t-Cost Tool 61 Based on the above three, a 25% incident duration savings is applied for all incidents. e data include incidents managed by CHART, including each incident duration.
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62 Guidelines for Quantifying Bene ts of Traf c Incident Management Strategies Figure D11. MD CHART I-495 traf c volume and incident count by operation time.
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Application and Assessment of FHWA TIM Benefit-Cost Tool 63 D.3.4 SSP Incident Information Incident count and duration by operational time and number of lanes blocked are the requisite inputs for this section. The final input is the percentage of estimated secondary incidents.
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64 Guidelines for Quantifying Bene ts of Traf c Incident Management Strategies Figure D14. SSP output from online interface.
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Application and Assessment of FHWA TIM Benefit-Cost Tool 65 D.4.2 Use of Tool by Others The developers of the FHWA TIM-BC tool applied it to a 10-mile stretch of I-287 in New York and observed a SSP BC ratio of 18.4. The tool for this application advised adverse fuel consumption and emissions outcomes, but the developers explained that some incidents may have the effect of slowing down fast-moving traffic to more fuel-efficient speeds.
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