Guide for Identifying, Classifying, Evaluating, and Mitigating Truck Freight Bottlenecks (2017) / Chapter Skim
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71 C h a p t e r 7 The bottleneck identification and mitigation process involves sorting truck bottleneck causes and matching them to mitigation strategies. Typically, state and local jurisdictions focus on truck bottlenecks on the National Highway Freight Network, the State Highway Freight Network, and local (e.g., MPO, county, city)
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72 Guide for Identifying, Classifying, evaluating, and Mitigating truck Freight Bottlenecks providing incentives to have more trucks operate during nighttime periods where congestion is minimal. Truck emissions factors will need to be applied to various mitigation strategies to determine which one(s)
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Options for Mitigating truck Bottlenecks 73 Cause Of Bottleneck Mitigation Measure Options to Consider Recurring Congestion Add capacity Reversible/convertible two-way left-turn lanes ITS solutions: ramp metering, real-time traveler info (e.g., sharing peak demand data) , appointment systems, load-matching, etc.
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74 Guide for Identifying, Classifying, evaluating, and Mitigating truck Freight Bottlenecks Cause Of Bottleneck Mitigation Measure Options to Consider Poor Signal Timing Signal synchronization Signal prioritization for trucks Right-/left-turn lane additions Appropriate truck turning radii Improve site distance (remove obstructions, improve lighting, etc.) Improve geometry at signalized intersections, including continuous flow intersections, diverging diamond interchange, etc.
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Options for Mitigating truck Bottlenecks 75 Cause Of Bottleneck Mitigation Measure Options to Consider Geometric -- Merge/Diverge Congestion Add auxiliary lane Interchange consolidation via collector-distributor system Restriping merge/diverge areas to provide additional lanes Ramp metering Syncing arterial signals to moderate flow of traffic merging onto and exiting the mainline Separate truck/auto traffic Geometric -- Narrow Bridges Widen travel lanes on bridges Widen shoulders on bridges Geometric -- Tunnels Reconstruct to add necessary height and/or adequate travel lane widths and shoulder widths Geometric -- Narrow Travel Lanes Restripe to widen travel lanes Consider use of shoulder or widening Process Delays -- Gate/Weigh Station Gate/border crossing technology improvements, appointment systems, radio frequency identification (RFID) readers, congestion-based tolls Processing (CBT)
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76 Guide for Identifying, Classifying, evaluating, and Mitigating truck Freight Bottlenecks Cause Of Bottleneck Mitigation Measure Options to Consider Process Delays -- Permit Acquisition Increase processing time for permit acquisition Allow for broader application of current permit categories Reduce number of trip types for which a permit is required Automate permit acquisition process Process Delays (Other) -- Truck Prohibitions/Route Restrictions: Size/ Weight, Hazardous Materials, And Oversized Loads Investigate reason for prohibitions/restrictions Match truck routes with appropriate infrastructure considering height and weight limits Table 7-1.
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From page 77... ...
Options for Mitigating truck Bottlenecks 77 • Active traffic management, and • Lane restriping. On arterials, operational improvements designed to increase throughput can include: • Signal retiming; • Improved channelization; and • Adding or changing traffic controls (e.g., replacing a signal with a roundabout, or removing stop signs that do not meet warrants)
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78 Guide for Identifying, Classifying, evaluating, and Mitigating truck Freight Bottlenecks corridor. The operational controls on those roads are then optimized to accept increased travel demand as travelers shift their route to take advantage of the parallel facilities.
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Options for Mitigating truck Bottlenecks 79 7.4 Mitigation Options for Operational Deficiencies Operational deficiencies occur when the existing operational control system is not working as well as it could be or when substandard roadway geometrics or a lack of adequate loading and unloading facilities force trucks to slow. This results in reduced roadway capacity, and therefore, many of these situations also are identified as recurring congestion, as noted above.
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80 Guide for Identifying, Classifying, evaluating, and Mitigating truck Freight Bottlenecks pass slower moving vehicles. Similarly, deceleration lanes on steep downhill grades allow trucks to maintain lower speeds and control.
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Options for Mitigating truck Bottlenecks 81 design vehicles [for example, a wheel base 40 truck (WB-40)
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82 Guide for Identifying, Classifying, evaluating, and Mitigating truck Freight Bottlenecks changing the road slope, adding truck climbing lanes, or using tunnels to bypass the grades. Emergency runaway truck ramps also improve truck safety on steep downhill grades.
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Options for Mitigating truck Bottlenecks 83 MPO CMP plans were found to be a common place for truck bottleneck mitigation efforts due in part to their responsibility for air quality conformity, but also due to their role in retaining and creating jobs and promoting economic sustainability. In these instances, improving goods movement is typically a part of the larger long-range plan, and the project screening and prioritization process often considers goods movement benefits.
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84 Guide for Identifying, Classifying, evaluating, and Mitigating truck Freight Bottlenecks linking segments identified as a bottleneck to different geometric characteristics of that roadway segment. 7.7.2 Washington State DOT Example of Mitigating Truck Bottlenecks Specific roadway attribute data can be used to indirectly or directly identify possible bottleneck causation.
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From page 85... ...
Options for Mitigating truck Bottlenecks 85 Bottleneck Characteristic Roadway Feature Measured Supporting Variables Available in WSDOT's GeoData Catalog Truck swept path width (turn area) Tight curves at intersections cause trucks to track off the roadway Horizontal alignment Intersection information Vertical curves Alignment of rolling roads with sight distance and headlight distance limitations Roadway Vertical Alignment Design Speed Vertical Curves Horizontal curves Radius of tight curves that can contribute to running off the road or rollovers and a need for trucks to slow down Roadway Horizontal Alignment Design Speed Horizontal Curve Where Design Speed Is Greater Than or Equal to 20 Roadway Design Speed Horizontal Curve Where Design Speed Is Less Than 20 Lane width Roads with narrow lanes slow trucks Lane Width Roadway Special Use Lanes (Truck Climbing Lanes, Acceleration Lanes)
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86 Guide for Identifying, Classifying, evaluating, and Mitigating truck Freight Bottlenecks Bottleneck Characteristic Roadway Feature Measured Supporting Variables Available in WSDOT's GeoData Catalog Other Information Truck relevant route and other travel factors that might support a field analysis Freight and Goods Transportation Systems Routes (Truck Relevant Routes) Truck AADT Divided Highways Urban-Rural Bridges Mileposts Intersections and ramps (curb return radii at intersection and ramps)
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