Guide for Identifying, Classifying, Evaluating, and Mitigating Truck Freight Bottlenecks (2017) / Chapter Skim
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Pages 43-56
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From page 43... ...
43 C h a p t e r 5 This chapter describes how to conduct analyses to identify and quantify truck bottlenecks. The first three subsections describe how to conduct this analysis for travel speed-based delay with the final subsection describing how to conduct this analysis for process-based delay.
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From page 44... ...
44 Guide for Identifying, Classifying, evaluating, and Mitigating truck Freight Bottlenecks • Whether delays occur only during some times of the year (e.g., only during the summer) or throughout the year; and • How these delays differ for trucks in comparison with all vehicles.
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From page 45... ...
Identify and Quantify truck Freight Bottlenecks 45 approaches to mitigating those bottlenecks. These detailed analyses can take into account key details about each study location (e.g., current local transportation improvement plans)
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From page 46... ...
46 Guide for Identifying, Classifying, evaluating, and Mitigating truck Freight Bottlenecks • Actual Truck Travel Time is the travel time experienced by trucks using that road segment for that time period. Delay only occurs when formula [1]
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Identify and Quantify truck Freight Bottlenecks 47 Delay occurs whenever speed drops below a set threshold. A significant issue in identifying bottlenecks is defining the threshold at which delay occurs.
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48 Guide for Identifying, Classifying, evaluating, and Mitigating truck Freight Bottlenecks demand is very high to maximize use of the facility. This measure reports only that delay which represents a loss of roadway throughput efficiency.
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Delay Threshold Description Typical/Specific Examples Delay from Free-Flow (Uncongested) Speeds Free-flow (uncongested)
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50 Guide for Identifying, Classifying, evaluating, and Mitigating truck Freight Bottlenecks separate month in the year. The delay is shown to peak in four urban areas labeled from "a" to "d" where "a" represents delay in the Indiana portion of the Chicago (IL)
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From page 51... ...
Identify and Quantify truck Freight Bottlenecks 51 The combined abilities to identify congestion locations on the basis of actual vehicle speeds and to compute and compare truck delays differently from passenger vehicle delays is one of the advantages of using the NPMRDS (or other datasets that provide truck-specific data) for congestion-related bottleneck identification.
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From page 52... ...
52 Guide for Identifying, Classifying, evaluating, and Mitigating truck Freight Bottlenecks Each of these statistics can be computed from the basic cube data structure. Reporting and examining these different measures is part of evaluating the relative importance of a bottleneck, as well as determining what approaches should be applied to help mitigate that delay.
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From page 53... ...
Identify and Quantify truck Freight Bottlenecks 53 than passenger cars would take if making that same trip, or they require trucks to carry less cargo than they would otherwise carry if not legally restricted from doing so. Both situations force trucks to travel additional miles, increasing the cost of freight delivery as a result of both additional labor hours and additional mileage driven.
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From page 54... ...
54 Guide for Identifying, Classifying, evaluating, and Mitigating truck Freight Bottlenecks timeframes) , nothing in the cube analysis structure describes the nontravel-time costs associated with moving trips to late-night hours.
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From page 55... ...
Identify and Quantify truck Freight Bottlenecks 55 The discussion of desktop bottleneck analysis suggested that the state DOT identify key truck trips occurring in the state. For example, these can be from major manufacturing areas of the state to major ports, intermodal yards, or the state border on the Interstate connecting with major cities in neighboring states.
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From page 56... ...
56 Guide for Identifying, Classifying, evaluating, and Mitigating truck Freight Bottlenecks road segment) , the GIS must be used to determine the best alternative travel path from the origin to the destination that does not include the restricted roadway segment.
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