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Urban Freight Lab

Research Keyword: Bottleneck

A bottleneck is a section of a highway or rail network that experiences operational problems such as congestion. Bottlenecks may result from factors such as reduced roadway width or steep freeway grades that can slow trucks.

West Seattle Bridge Case Study (Phase I)

Background
West Seattle is an area of the city of Seattle located on a peninsula west of the Duwamish waterway and east of the Puget Sound. In March 2020, the West Seattle High Bridge (WSHB), the main bridge connecting West Seattle to the rest of the city, was closed indefinitely to traffic due to its increasing rate of structural deterioration. Moreover, access to the Spokane Street Lower Bridge, a smaller bridge connecting West Seattle with Harbor Island and the rest of the city, was also restricted; prioritizing heavy freight, public transit, and emergency vehicles. After the bridge closure and restrictions, the total number of vehicle travel lanes crossing the Duwamish River was reduced from 21 to 12.

The unexpected closure of WSHB disrupted passenger and freight mobility to and from West Seattle, increasing travel times and generating bottlenecks on the remaining bridges, which can potentially negatively impact the livability of the peninsula as well as its economy and the environment. The situation might further deteriorate as traffic demand to and from West Seattle increases during recovery from the COVID-19 pandemic.

The Seattle Department of Transportation (SDOT) is taking actions to monitor changes in travel behavior to/from West Seattle and identify and implement strategies that could mitigate the negative impacts caused by the WSHB closure.

Goals
SDOT has engaged the Urban Freight Lab to conduct research to explore strategies to alleviate congestion impacts and minimize the disruption of goods and service delivery to West Seattle.

The purpose of this study is to support SDOT to:

  1. understand current freight movements and freight demand in West Seattle;
  2. identify a data-driven mitigation strategy for freight and service flow to and from West Seattle;
  3. assess ex-ante the effectiveness of an implemented strategy.

The freight operations considered and analyzed within the scope of the project are consumer goods and services destined for West Seattle residents and businesses. Intermediate goods and raw materials destined for construction of production and other goods transiting through West Seattle but not destined for local residents or businesses will not be studied.

Continuation
This project continues with the West Seattle Bridge Case Study Phase II.

Paper

A Mobile Application for Collecting Task Time Data for Value Stream Mapping of the Final 50 Feet of Urban Goods Delivery Processes

 
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URL: https://doi.org/10.1177%2F1541931218621410
Publication: Proceedings of the Human Factors and Ergonomics Society Annual Meeting
Volume: 62
Pages: 1808-1812
Publication Date: 2018
Summary:

Delivery options have become very diverse with online shoppers demanding faster delivery options (e.g, 2-day delivery, same day delivery options) and more personalized services. For this reason, transportation planners, retailers, and delivery companies are seeking ways to better understand how best to deliver goods and services in urban areas while minimizing disruption to traffic, parking, and building operations. This includes understanding vertical and horizontal goods movements within urban areas.

The goal of this project is to capture the delivery processes within urban buildings in order to minimize these disruptions. This is achieved using a systems approach to understanding the flow of activities and workers as they deliver goods within urban buildings. A mobile application was designed to collect the start and stop times for each task within the delivery process for 31 carriers as they deliver goods within a 62-story office building.

The process flow map helped identify bottlenecks and areas for improvements in the final segment of the delivery operations: the final 50 feet. It also highlighted consistent tasks conducted by all carriers as well as differences with given carrier type. This information is useful to help decision-makers plan appropriately for the design of future cities that encompass a variety of delivery processes.

Authors: Haena KimDr. Anne Goodchild, Linda Ng Boyle
Recommended Citation:
Kim, Haena, Linda Ng Boyle, and Anne Goodchild. (2018) "A Mobile Application for Collecting Task Time Data for Value Stream Mapping of the Final 50 Feet of Urban Goods Delivery Processes." In Proceedings of the Human Factors and Ergonomics Society Annual Meeting, 62(1), 1808–1812. https://doi.org/10.1177/1541931218621410
Presentation

Development and Application of a Framework to Classify and Mitigate Truck Bottlenecks to Improve Freight Mobility

 
Download PDF  (1.14 MB)
 
Download Slides PDF  (1.14 MB)
URL: https://trid.trb.org/view/1494739
Publication: Transportation Research Record: Journal of the Transportation Research Board
Volume: TRN Annual Meeting
Publication Date: 2018
Summary:

This paper presents a framework to classify and mitigate roadway bottlenecks and that is designed to improve freight mobility. This is in recognition that roadway operations for trucks are under studied, truck-only bottlenecks are often not identified and freight-specific problem areas are therefore often overlooked. The framework uses four-steps:

Step 1: identifies and locates the roadway sections where vehicle travel time is in excess of what would normally occur.

Step 2: made possible by increasingly available truck probe data, identifies bottlenecks for all vehicles or for trucks only. This is necessary to identify bottlenecks that notably impact freight mobility and might not be identified by car-based approaches.

Step 3: classifies bottlenecks as travel speed-based or process-based. This selects the mitigation treatments as mainly due to operational or roadway limitations.

Step 4: which is the core of the paper, supports the mitigation process by determining the cause of the bottleneck. The bottlenecks are identified as due to congestion, limitations where roadway design slows all vehicles, or where a truck’s size or weight can slow vehicles (such as tight curves or bridge restrictions).

The paper present a review of specific roadway attributes that limit a truck’s mobility and is used to suggest mitigation. The framework is demonstrated using a case study. The framework is designed to be applied by planning and infrastructure agencies who want to locate and address freight bottlenecks in a systematic manner using available resources as well as by researchers interested in linking roadway attributes to truck mobility.

Authors: Dr. Ed McCormackDr. Anne Goodchild, William Eisele, Mark Hallenbeck
Recommended Citation:
McCormack, Edward, Anne Goodchild, W. Eisele, and Mark Hallenbeck. "Development and Application of a Framework to Classify and Mitigate Truck Bottlenecks to Improve Freight Mobility." TRN Annual Meeting, Washington D.C. 2018.