Efficiency and Reliability in Freight Transportation
This report focuses on improving the methodology for analyzing efficiency and reliability for freight transportation, dealing primarily with trucking though the tools can be applied to other modes. The freight industry has a continuing concern with reliability in order to be competitive. Late and early shipments are included in the problem-causing inefficiencies that freight companies must face. The emphasis on just-in-time manufacturing has squeezed buffer stock out of the logistics supply chain and has also raised the risk of stock-outs. Because storage space is also reduced as, early arrival becomes a problem. When reliability suffers, all participants in the supply chain have to make extra efforts to buffer the process to ensure that delivery schedules are met. The costs of producing goods and services increase and more resources must be devoted to freight activities to make the economic system work. The authors’ research produced several insights that will affect the way in which freight reliability analyses are performed. Freight reliability is not about travel times, but whether a shipment arrives or departs on time; reliability is the probability of arriving or departing during the on-time window. Minimizing variances in travel times remains important, but there may be no value in doing so once the desired on-time performance has been achieved. The arrival time and often the departure time are what matter, the goal being on-time delivery or pickup. Estimates of future travel times, based on past performance, become extremely important. Path search algorithms need assumptions about what the network operating conditions will be in the future and work backwards to determine what path should be used and when to depart. On-time performance is measured in terms of both departure and arrival, separately and in combination. The objective is to find routes that maximize on-time performance. Timestamps collected at network nodes (intersections or interchanges) tend to be ambiguous, but collecting timestamps at the midpoints of the links is better. While the focus is on on-time performance, there is still a critical need to compute travel times of network segments and paths. Section 2 of the report presents three methods for doing this. Section 4 presents two methods for considering reliability in developing solutions to vehicle routing and scheduling problems. Section 5 presents a method for considering the reliability of different sites for distribution centers, using Monte Carlo simulation to assess the reliability of the delivery service provided by distribution center sites.
- Record URL:
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- Summary URL:
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Supplemental Notes:
- This document was sponsored by the U.S. Department of Transportation, University Transportation Centers Program.
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Corporate Authors:
National Transportation Center at Maryland
1124 Glenn Martin Hall
University of Maryland
College Park, MD United States 20742Office of the Assistant Secretary for Research and Technology
University Transportation Centers Program
Department of Transportation
Washington, DC United States 20590North Carolina State University, Raleigh
Department of Civil, Construction, and Environmental Engineering
2501 Stinson Drive, Campus Box 7908
Raleigh, NC United States 27695-7908 -
Authors:
- List, George
- Williams, Elizabeth
- Addison, Jeremy
- Morsali, Atefeh
- Publication Date: 2017-7
Language
- English
Media Info
- Media Type: Digital/other
- Edition: Final Report
- Features: Figures; References; Tables;
- Pagination: 133p
Subject/Index Terms
- TRT Terms: Arrivals and departures; Economic efficiency; Methodology; On time performance; Reliability; Routes and routing; Travel time; Trucking
- Uncontrolled Terms: Time stamps
- Subject Areas: Freight Transportation; Operations and Traffic Management; Planning and Forecasting;
Filing Info
- Accession Number: 01667564
- Record Type: Publication
- Report/Paper Numbers: NTC2014-SU-R-06
- Files: UTC, TRIS, ATRI, USDOT
- Created Date: Apr 27 2018 12:23PM