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Article

The Freight of the West

 
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Publication: Thinking Cities
Volume: December 2017
Pages: 82-85
Publication Date: 2017
Summary:

More than 80 percent of Americans have purchased goods online and, in 2016, more than 8 percent of all retail sales in the U.S. took place online. The growth of ecommerce is putting increasing pressure on local governments to rethink how they manage street curb parking and alley operations for trucks and other delivery vehicles. It is also forcing building developers and managers to plan for the influx of online goods.

To develop practical solutions to these problems, in 2016 the University of Washington launched the Urban Freight Lab (UFL), a partnership between private and public industry stakeholders. The UFL provides a place for companies and public agencies to work together to develop and ground-test low-cost, promising solutions to deliver these goods while maintaining livability and economic vitality.

As part of this research effort, a three-year strategic research partnership with the City of Seattle Department of Transportation (SDOT) has been established to advance understanding of urban goods movement in support of the City’s goals for safe, predictable and efficient goods movement and economic vibrancy.

By entering into a long-term strategic partnership with the university and industry, SDOT demonstrated its interest in developing innovative solutions to achieve their policy goals. The city’s willingness to pilot test and potentially adopt solutions that provided both public and private good was essential in attracting private sector firms to engage fully in the work.

The Urban Freight Lab

In 2016, the Urban Freight Lab recruited founding industry members from Charlie’s Produce, Costco Wholesale, Nordstrom, UPS, and the United States Postal Service (USPS) to develop solutions to improve the way goods are delivered in the urban environment.

Private sector members of the Urban Freight Lab at the University of Washington, in partnership with SDOT, are using a systems engineering approach to solve delivery problems that overlap the spheres of control of the city and business sector.

The Lab has created a multi-year strategic research plan with principles and innovative approaches to produce evidence-based improvement strategies.

The role of the Urban Freight Lab is to be a living laboratory where potential solutions are generated, evaluated, and then pilot-tested on real city streets. Members provide clear and open input as to whether proposed solutions are sustainable in their and other firms’ business models.

The Final 50 Feet

The Urban Freight Lab and its members have defined and focused on the Final 50 Feet; the urban supply chain segment that begins where delivery vehicles park at the curb, alley or in a building’s freight parking space. It tracks the delivery process inside buildings and ends at the receipt of goods by the receiver. The Final 50 Feet concept represents the first time that the Lab have identified the importance of analyzing deliveries moving along the street grid and in cities’ vertical space (office, hotel, retail and residential towers) as a unified goods delivery system.

Development of the Final 50 Feet concept is the necessary first step in defining rigorous, goal-oriented improvement teams that can take coordinated action to reduce truck trips, delivery delays, cost, emissions, and improve delivery service to tenants and consumers. It provides them with the ability to analyze and improve the process flows meaningfully from the beginning-to-end of the last piece of the urban goods system.

The Urban Freight Lab members and SDOT have identified two priority goals, with both public and private benefits, for the 2017-2020 research partnership:

  1. Reduce the number of failed first delivery attempts. The failed first delivery can be as high as 15 percent. Benefits of reducing failed first deliveries include:
    • Improve urban online shoppers’ experiences and protect retailers’ brands;
    • Cut business costs for the retail sector and logistics firms;
    • Lower traffic congestion in cities, as delivery trucks could make up to 15 percent fewer trips while still completing the same number of deliveries.
  2. Reduce dwell time. The time a truck is parked in a load/ unload space. There are both public and private benefits to reaching this goal, including:
    • Lower costs for delivery firms, and therefore potentially lower costs for their customers;
    • Better utilization of public and private truck load/unload spaces;
    • Less congestion, as spaces turn over more quickly.

Overview of the Innovative Approaches Taken to Identify and Quantitatively Assess the Final 50 Feet of the Urban Goods Delivery System

Building the first comprehensive database of urban off-street infrastructure for delivery and pick-up operations

The urban goods delivery system includes both public and private facilities. While on-street parking facilities are well documented in Seattle’s databases, facilities out of the public right of way (i.e. privately held) are not. SCTL research assistants, developed a ground-truthed data collection method to build a comprehensive database inventory, capturing geospatial locations and documenting the visible features of all private freight parking infrastructure in five urban centers in the Seattle area.

For this task, the team collaborated with one of the private carrier members of the Urban Freight Lab to further improve the accuracy of the data collection method. Carrier drivers with deep knowledge of city routes and infrastructure, review the closed door locations.

This review allowed the Lab to rule out 98 percent (206) of the locations behind closed doors, reducing uncertainty in the final database from 38 percent to less than 1 percent.

Researchers found that 87 percent of buildings in the City’s dense urban centers are completely reliant on nearby public commercial vehicle load zones (CVLZs) and alley truck load/unload spaces to receive goods deliveries. These buildings do not have underground or adjacent freight bays on their property.

Building a delivery process flow for delivery inside the building environment

The Lab created detailed process flow maps of the Final 50’ in and around five prototype city buildings in Seattle, Washington.

The team collected original data by following delivery persons from the buildings’ freight bays or nearby commercial vehicle zones (CVLZs) into each of the buildings, until delivery was completed or the return to the truck when there was a failed delivery. The Lab designed and built an application for collectors to enter the precise time that the delivery people began and ended each process step. The team then collected data for up to a week in peak delivery periods for each building. They analyzed the range and average of delay in the process steps to understand where improvement strategies will have the most significant ability to achieve project goals (13). Based on this analysis, the Lab found that the greatest opportunities to reduce the number of failed first deliveries and dwell time in truck load/unload spaces are inside buildings when delivery persons:

  • Interact with security personnel; and
  • Attempt to locate tenants.

In the next phase of the Final 50 Feet project, the Urban Freight Lab and SDOT will pilot test promising improvement strategies in and on the streets around the Seattle Municipal Tower over four weeks.

Benefits

Final 50’ project findings will be used to provide decision support to city officials and private-sector firms managing scarce resources. By applying systems engineering and evidence-based planning, we can make receiving online goods as efficient as ordering them – without clogging city streets and curb space.

We have received requests from many other cities, including Washington, D.C., to share results and lessons learned during the Freight Master Plan development process and early actions coming out of this three-year program. Seattle is committed to being a leader in urban goods policy and problem-solving and keeping our economy thriving.

According to City of Seattle officials Mr. Christopher Eaves and Ms. Jude Willcher, “Seattle is one fastest growing cities in the country. The Seattle Department of Transportation is committed meeting the urban goods delivery challenges facing most big cities in the U.S. We know that issuing parking tickets to companies who are simply trying to meet the daily delivery needs of residents and businesses isn’t the right solution. So, our goal is to identify and implement scalable strategies that improve deliveries at existing building, as well as initiate strategic research to mine new data to improve and inform new construction designs that support freight and delivery in the city. And we are incredibly grateful to have found a strong and innovative partner in the UW Freight Lab and SCTL”.

Recommended Citation:
Urban Freight Lab. “The freight of the West” Thinking Cities Magazine, December 2017, 82-85
Article

More Online Shopping Means More Delivery Trucks. Are Cities Ready?

 
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Publication: The Conversation
Publication Date: 2016
Summary:

Two converging trends — the rise of e-commerce and urban population growth — are creating big challenges for cities. Online shoppers are learning to expect the urban freight delivery system to bring them whatever they want, wherever they want it, within one to two hours. That’s especially true during the holidays, as shipping companies hustle to deliver gift orders on time.

City managers and policymakers were already grappling with high demand and competing uses for scarce road, curb, and sidewalk space. If cities do not act quickly to revamp the way they manage increasing numbers of commercial vehicles unloading goods in streets and alleys and into buildings, they will drown in a sea of double-parked trucks.

The University of Washington has formed a new Urban Freight Lab to solve delivery system problems that cities and the business sector cannot handle on their own. Funders of this long-term strategic research partnership include the City of Seattle Department of Transportation (SDOT) and five founding corporate members: Costco, FedEx, Nordstrom, UPS, and the U.S. Postal Service.

The core problem facing cities is that they are trying to manage their part of a sophisticated data-powered 21st-century delivery system with tools designed for the 1800s — and they are often trying to do it alone. Consumers can order groceries, clothes, and electronics with a click, but most cities only have a stripe of colored paint to manage truck parking at the curb. The Urban Freight Lab brings building managers, retailers, logistics and tech firms, and city government together to do applied research and develop advanced solutions.

Moving more goods, more quickly

We have reached the point where millions of people who live and work in cities purchase more than half of their goods online. This trend is putting tremendous pressure on local governments to rethink how they manage street curb parking and alley operations for trucks and other delivery vehicles. It also forces building operators to plan for the influx of online goods. A few years ago, building concierges may have received a few flower bouquets. Now many are sorting and storing groceries and other goods for hundreds of residents every week.

In the first quarter of 2016, almost 8 percent of total U.S. retail sales took place online. Surging growth in U.S. online sales has averaged more than 15 percent year-over-year since 2010. Black Friday web sales soared by 22 percent from 2015 to 2016.

Online shoppers’ expectations for service are also rising. Two out of three shoppers expect to be able to place an order as late as 5:00 p.m. for next-day delivery. Three out of five believe orders placed by noon should be delivered the same day, and one out of four believe orders placed by 4:00 p.m. or later should still be delivered on the same day.

City living and shopping is still all about location, location, location. People are attracted to urban neighborhoods because they prefer to walk more and drive less. Respondents in the 2015 National Multifamily Housing Council-Kingsley Apartment Resident Preferences Survey preferred walking to grocery stores and restaurants rather than driving by seven points. But this lifestyle requires merchants to deliver goods to customers’ homes, office buildings or stores close to where they live.

Smarter delivery systems

SDOT recently published Seattle’s first draft Freight Master Plan, which includes high-level strategies to improve the urban goods delivery system. But before city managers act, they need evidence to prove which concepts will deliver results.

To lay the groundwork for our research, an SCTL team led by Dr. Ed McCormack and graduate students Jose Machado Leon and Gabriela Giron surveyed 523 blocks of Seattle’s downtown (including Belltown, the commercial core, Pioneer Square and International District), South Lake Union and Uptown urban centers in the fall of 2016. They compiled GIS coordinates and infrastructure characteristics for all observable freight loading bays within buildings. Our next step is to combine this information with existing GIS layers of the city’s curbside commercial vehicle load zones and alleys to produce a complete map of Seattle’s urban delivery infrastructure.

In our first research project, the Urban Freight Lab is using data-based process improvement tools to purposefully manage both public and private operations of the Final-50-Feet space. The final 50 feet of the urban delivery system begins when a truck stops at a city-owned curb, commercial vehicle load zone or alley. It extends along sidewalks and through privately owned building freight bays, and may end in common areas within a building, such as the lobby.

One key issue is failed deliveries: Some city residents don’t receive their parcels due to theft or because they weren’t home to accept them. Could there be secure, common drop-off points for multiple carriers to use, attached to bus stops or on the sidewalk?

The most pressing issue is the lack of space for trucks to park and deliver goods downtown. It may be possible to use technology to get more use out of existing commercial vehicle load zones. For example, trucks might be able to use spaces now reserved exclusively for other uses during off-peak hours or seasons.

To analyze the fundamental problems in the urban logistics system, our research team will create process flow maps of each step in the goods delivery process for five buildings in Seattle. We will collect data and build a model to analyze “what if” scenarios for one location. Then we will pilot test several promising low-cost, high-value actions on Seattle streets in the fall of 2017. The pilots may involve actively managing city load zones and alleys to maximize truck use, or changing the way people use freight elevators.

By using information technologies and creative planning, we can make receiving online goods as efficient as ordering them — without clogging our streets or losing our packages.

Recommended Citation:
Goodchild, A., & Ivanov, B. (2016, December 20). More online shopping means more delivery trucks. Are cities ready? The Conversation. https://theconversation.com/more-online-shopping-means-more-delivery-trucks-are-cities-ready-67686.
Article

Where’s My Package? Common Carrier Freight Lockers Can Ease City Traffic and Prevent Failed Deliveries

Publication: The Conversation
Publication Date: 2018
Summary:

Online shopping is a big convenience for many Americans, but porch piracy can ruin the experience. For example, Mikaela Gilbert lived in a row house in West Philadelphia while she studied systems engineering at the University of Pennsylvania. By her junior year, Gilbert had lost enough packages to thieves that she devised an elaborate three-pronged security strategy.

Her first line of defense was having online purchases shipped to a friend who lived in a high-rise apartment where a doorman secured incoming packages. She also sent orders to her parents’ house in New Jersey when she had a visit home planned. But both of those options were hugely inconvenient, so sometimes she routed deliveries to her place after texting her seven housemates to be on the lookout.

When Amazon installed branded delivery lockers near the center of campus, Gilbert began receiving packages there, which was less stressful than managing a small army of collaborators. But it limited her shopping to just one retailer. When Amazon didn’t have something she wanted, she had to fall back on her circle of friends.

Retailers delivering to a customers’ homes also want to avoid these situations. Research at our lab has identified a promising alternative: publicly accessible common carrier freight lockers where all retailers can leave packages for pickup.

So many stops, so little time
Like Amazon’s branded lockers, common carrier lockers are automated, self-service storage units that provide a secure location for customers to receive online purchases. However, any retailer or delivery firm can access them. Some private buildings have such lockers now, but those are only open to residents. Our study examined the effectiveness of locating them in public spaces in dense urban areas, where they can be available to everyone.

The University of Washington’s Urban Freight Lab is a structured research work group composed of leading retail, logistics and delivery firms. We partner with the Seattle Department of Transportation, collect and analyze data, and run pilot tests of promising solutions in Seattle’s Center City area. Our focus is on solving urban delivery issues in an age when e-commerce is exploding, city populations are expanding, and gridlock is reaching epic levels.

In its first report, published in early 2018, the Lab analyzed the “Final 50 Feet” of the urban goods delivery system – the last leg of the supply chain. It begins when trucks pull into a parking space and stop moving, whether at the curb, in an alley, or at a building’s loading dock or internal freight bay. From there, it follows delivery people inside urban towers, ending where customers receive their packages.

Researchers discovered two especially thorny challenges in this segment of the chain: extended “dwell time,” when trucks are parked in load/unload spaces too long, and failed first delivery attempts due to causes that include porch piracy. Solving these puzzles could reduce delivery costs, traffic congestion and crime rates, and improve online shoppers’ experiences.

Delivering packages one at a time to individual homes or offices is time-consuming and requires driving to multiple locations and parking in multiple spaces. It also results in failed first delivery rates of up to 15 percent in parts of some cities, according to some of our lab’s member companies. Instead, we decided to try creating delivery density in a single location right where the trucks unloaded.

Centralized lockers where people live and work
Accordingly, the Urban Freight Lab’s second research project pilot-tested placing a common carrier locker system in the 62-floor Seattle Municipal Tower in downtown Seattle’s financial district. This step cut the time required to make deliveries in the tower by 78 percent. The next question was where to locate more of these delivery density points, or “mini-distribution nodes,” as the study called them.

Amazon, which is headquartered in Seattle, had already approached regional transportation agency Sound Transit about locating its branded lockers at the agency’s Link light rail stations. But public stewards of the property – the Seattle Department of Transportation, Sound Transit and King County Metro – did not want to advantage one carrier or retailer over others. Instead, we suggested locating common carrier lockers.

The transit agencies saw that this could reduce delivery truck traffic in neighborhoods they served, easing congestion and reducing vehicle emissions. And their mobility hub policies aimed to create lively public spaces that offered not only multiple transportation modes but lots of convenient amenities.

In a survey of 185 riders at three transit stations, our lab’s third research study found strong interest in the lockers, with up to 67 percent of respondents at each station willing to use them and the vast majority willing to carry a package three to six blocks to do so. These responses, plus the fact that some 137,000 people lived within a 30-minute walk of the three stations, suggested that tens of thousands of Seattle residents would be willing to use common carrier lockers at those stations.

For retailers like Nordstrom, the lockers represent a potential solution to porch piracy and other glitches associated with online shopping. “Rather than leaving the package at a door, some carriers want customers to come to their location to collect the package, while others might redeliver,” Loren VandenBerghe, director of transportation for Nordstrom, told us. “Whatever the process, the customer has to track down the package. Instead, we’d prefer to get the package in our customer’s hands when they expect it.”

Researchers have developed criteria for selecting locker locations and chosen five possible sites at or near the transit stations for pilot testing. We have received funding from the U.S. Department of Energy to expand use of common carriers lockers in public spaces to a larger area in Seattle’s dense urban core and start actively managing the load/unload space network with new technology. Delivery drivers will be able to pull right up to lockers and unload goods, and riders can pick up their packages when they hop on or off a bus – making it much more convenient than waiting for a truck and scanning the street for porch pirates.

Recommended Citation:
Goodchild, A. (2018, December 18). Where’s my package? Common carrier freight lockers can ease city traffic and prevent failed deliveries. The Conversation. https://theconversation.com/wheres-my-package-common-carrier-freight-lockers-can-ease-city-traffic-and-prevent-failed-deliveries-108455
Article

How Many Amazon Packages Get Delivered Each Year?

Publication: The Conversation
Publication Date: 2022
Summary:

How many Amazon packages get delivered each year? – Aya K., age 9, Illinois

It’s incredibly convenient to buy something online, right from your computer or phone. Whether it’s a high-end telescope or a resupply of toothpaste, the goods appear right at your doorstep. This kind of shopping is called “e-commerce” and it’s becoming more popular each year. In the U.S., it has grown from a mere 7% of retail purchases in 2012 to 19.6% of retail and $791.7 billion in sales in 2020.

Amazon’s growing reach
For Amazon, the biggest player in e-commerce, this means delivering lots of packages.

In 2021 Amazon shipped an estimated 7.7 billion packages globally, based on its nearly $470 billion in sales.

In 2021 Amazon shipped an estimated 7.7 billion packages globally.

If each of these packages were a 1-foot square box and they were stacked on top of one another, the pile would be six times higher than the distance from the Earth to the Moon. Laid end to end, they would wrap around the Earth 62 times.

Back in the early 2010s, most things bought from Amazon.com were shipped using a third-party carrier like FedEx or UPS. In 2014, however, Amazon began delivering packages itself with a service called “Fulfilled by Amazon.” That’s when those signature blue delivery vans started appearing on local streets.

Since then, Amazon’s logistics arm has grown from relying entirely on other carriers to shipping 22% of all packages in the U.S. in 2021. This is greater than FedEx’s 19% market share and within striking distance of UPS’s 24%. Amazon’s multichannel fulfillment service allows other websites to use its warehousing and shipping services. So your order from Etsy or eBay could also be packed and shipped by Amazon.

The supply chain
To handle that many packages, shipping companies need an extensive network of manufacturers, vehicles and warehouses that can coordinate together. This is called the supply chain. If you’ve ever used a tracking number to follow a package, you’ve seen it in action.

People who make decisions about where to send vehicles and how to route packages are constantly trying to keep costs down while still getting packages to customers on time. The supply chain can do this very effectively, but it also has downsides.

More delivery vehicles on the road produce more greenhouse gas emissions that contribute to climate change, along with pollutants like nitrogen oxides and particulate matter that are hazardous to breathe. Traffic congestion is also a major concern in cities as delivery drivers try to find parking on busy streets.

Urban freight solutions
Are there ways to balance the increasing number of deliveries while making freight safe, sustainable and fast? At the University of Washington’s Urban Freight Lab, we work with companies like Amazon and UPS and others in the shipping, transportation and real estate sectors to answer questions like this. Here are some solutions for what we and our colleagues call the “last mile” – the last leg of a package’s long journey to your doorstep.

  • Electrification: Transitioning from gasoline and diesel vehicles to fleets of electric or other zero-emission vehicles reduces pollution from delivery trucks. Tax credits and local policies, such as creating so-called green loading zones and zero-emission zones for clean vehicles, create incentives for companies to make the switch.
  • Common carrier lockers: Buildings can install lockers at central locations, such as busy transit stops, so that drivers can drop off packages without going all the way to your doorstep. When you’re ready to pick up your items, you just stop by at a time that’s convenient for you. This reduces both delivery truck mileage and the risk of packages being stolen off of porches.
  • Cargo bicycles: Companies can take the delivery truck out of the equation and use electric cargo bicycles to drop off smaller packages. In addition to being zero-emission, cargo bicycles are relatively inexpensive and easy to park, and they provide a healthier alternative for delivery workers.

To learn more about supply chains and delivery logistics, check with your town or city’s transportation department to see if they are testing or already have goods delivery programs or policies, like those in New York and Seattle. And the next time you order something for delivery, consider your options for receiving it, such as walking or biking to a package locker or pickup point, or consolidating your items into a single delivery.

Package delivery can be both convenient and sustainable if companies keep evolving their supply chains, and everyone thinks about how they want delivery to work in their neighborhoods.

Recommended Citation:
Goodchild, A. How many Amazon packages get delivered each year? The Conversation. https://theconversation.com/how-many-amazon-packages-get-delivered-each-year-187587
Article, Special Issue

Urban Logistics: From Research to Implementation

 
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Publication: Research in Transportation Business & Management (RTBM)
Volume: 45 (A)
Publication Date: 2022
Summary:

To address the accessibility and sustainability challenges of urban logistics it is important to consider urban logistics from a number of perspectives.

This includes considering:

  • spatial context i.e. not focusing solely on the urban center or core but also in terms of actions taken in broader logistics and supply chain management.
  • stakeholders i.e. including all key decision makers and constituents.
  • complexity and heterogeneity of activities (range of vehicles used, the products carried, location of distribution centers, and the variety found in city size, form, and governance).

This diversity of perspectives, and their influence on the urban freight system, makes it challenging to identify simple solutions to problems.

A number of forces are also at work impacting change in the urban logistics system. Technological innovation affecting urban logistics includes digitalization, e.g. the Internet of Things (important in terms of connected objects) and big data. These developments are already established and beginning to have an impact or at least implications in the field of urban logistics and freight transport. However, problems will not be solved by technology alone and it is essential to understand how behavior (at the individual and corporate level) influences outcomes and needs to change. Research needs to address interactions between stakeholders and the role of city authorities in promoting innovation and change.

Cities are complex environments and urban logistics has to adapt to these demands. The complexity of cities also gives rise to a debate about the extent to which problems (and their possible solutions) may be considered context-specific. This leads to questions relating to how initiatives should be scaled up to gain greater traction in dealing with challenges now and in the future. It is important to learn as much as possible from the high number of projects and new services that have been implemented in cities over the past ten years. These range from initiatives related to electric vehicles, through locker box systems and the role of the receiver in making change happen. How to learn and then apply the lessons from projects is an important question. In many cases it has been argued that the underlying business model has not been addressed successfully leading to the problem of projects lasting only as long as some form of project funding is available.

Authors: Dr. Anne Goodchild, Michael Browne (University of Gothenburg)
Recommended Citation:
Michael Browne, Anne Goodchild. Urban Logistics: From Research to Implementation, Research in Transportation Business & Management, Volume 45 (A) 2022, 100913, ISSN 2210-5395, https://doi.org/10.1016/j.rtbm.2022.100913.
Article

A Framework to Assess Pedestrian Exposure Using Personal Device Data

 
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Publication: Human Factors and Ergonomics Society
Volume: 66 (1)
Pages: 320 - 324
Publication Date: 2022
Summary:

Capturing pedestrian exposure is important to assess the likelihood of a pedestrian-vehicle crash. In this study, we show how data collected on pedestrians using personal electronic devices can provide insights on exposure. This paper presents a framework for capturing exposure using spatial pedestrian movements based on GPS coordinates collected from accelerometers, defined as walking bouts. The process includes extracting and cleaning the walking bouts and then merging other environmental factors. A zero-inflated negative binomial model is used to show how the data can be used to predict the likelihood of walking bouts at the intersection level. This information can be used by engineers, designers, and planners in roadway designs to enhance pedestrian safety.

Authors: Haena Kim, Grace Douglas, Linda Ng Boyle, Anne Moudon, Steve Mooney, Brian Saelens, Beth Ebel
Recommended Citation:
Douglas, G., Boyle, L. N., Kim, H., Moudon, A., Mooney, S., Saelens, B., & Ebel, B. (2022). A Framework to Assess Pedestrian Exposure Using Personal Device Data. Proceedings of the Human Factors and Ergonomics Society Annual Meeting. https://doi.org/10.1177/1071181322661319
Article

Local Area Routes for Vehicle Routing Problems

 
Download PDF  (1.44 MB)
Publication: arXiv
Publication Date: 2022
Summary:
In this research we consider an approach for improving the efficiency and tightness of column generation (CG) methods for solving vehicle routing problems. This work builds upon recent work on Local Area (LA) routes. LA routes rely on pre-computing (prior to any call to pricing during CG) the lowest cost elementary sub-route (called an LA arc) for each tuple consisting of the following: (1) a customer to begin the LA arc, (2) a customer to end the LA arc, which is far from the first customer, (3) a small set of intermediate customers nearby the first customer. LA routes are constructed by concatenating LA arcs where the final customer in a given LA arc is the first customer in the subsequent LA arc. A Decremental State Space Relaxation (DSSR) method is used to construct the lowest reduced cost elementary route during the pricing step of CG. We demonstrate that LA route based solvers can be used to efficiently tighten the standard set cover vehicle routing relaxation using a variant of subset row inequalities (SRI). However, SRI are difficult to use in practice as they alter the structure of the pricing problem in a manner that makes pricing difficult. SRI in their simplest form state that the number of routes servicing two or three members of a given set of three customers cannot exceed one. We introduce LA-SRI, which in their simplest form state that the number of LA arcs (in routes in the solution) including two or more members of a set of three customers (excluding the final customer of the arc) cannot exceed one. We exploit the structure of LA arcs inside a Graph Generation based formulation to accelerate convergence of CG. We apply our LA-SRI to CVRP and demonstrate that we tighten the LP relaxation, often making it equal to the optimal integer solution, and solve the LP efficiently without altering the structure of the pricing problem.

 

Authors: Amelia Regan, Udayan Mandal, Julian Yarkony
Recommended Citation:
Mandal, U., Regan, A., & Yarkony, J. (2022). Local Area Subset Row Inequalities for Efficient Exact Vehicle Routing. arXiv preprint arXiv:2209.12963.
Article

Local Area Subset Row Inequalities for Efficient Exact Vehicle Routing

 
Download PDF  (1.44 MB)
Publication:  arXiv e-prints (2022): arXiv-2209
Publication Date: 2022
Summary:
In this research we consider an approach for improving the efficiency and tightness of column generation (CG) methods for solving vehicle routing problems. This work builds upon recent work on Local Area (LA) routes. LA routes rely on pre-computing (prior to any call to pricing during CG) the lowest cost elementary sub-route (called an LA arc) for each tuple consisting of the following: (1) a customer to begin the LA arc, (2) a customer to end the LA arc, which is far from the first customer, (3) a small set of intermediate customers nearby the first customer. LA routes are constructed by concatenating LA arcs where the final customer in a given LA arc is the first customer in the subsequent LA arc. A Decremental State Space Relaxation (DSSR) method is used to construct the lowest reduced cost elementary route during the pricing step of CG. We demonstrate that LA route based solvers can be used to efficiently tighten the standard set cover vehicle routing relaxation using a variant of subset row inequalities (SRI). However, SRI are difficult to use in practice as they alter the structure of the pricing problem in a manner that makes pricing difficult. SRI in their simplest form state that the number of routes servicing two or three members of a given set of three customers cannot exceed one. We introduce LA-SRI, which in their simplest form state that the number of LA arcs (in routes in the solution) including two or more members of a set of three customers (excluding the final customer of the arc) cannot exceed one. We exploit the structure of LA arcs inside a Graph Generation based formulation to accelerate convergence of CG. We apply our LA-SRI to CVRP and demonstrate that we tighten the LP relaxation, often making it equal to the optimal integer solution, and solve the LP efficiently without altering the structure of the pricing problem.

 

Authors: Amelia Regan, Udayan Mandal, Julian Yarkony
Recommended Citation:
Mandal, U., Regan, A., & Yarkony, J. (2022). Local Area Subset Row Inequalities for Efficient Exact Vehicle Routing. arXiv preprint arXiv:2209.12963.
Article

Giving Curb Visibility to Delivery Drivers

 
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Publication: American Planning Association | 2022 State of Transportation Planning
Pages: 134-143
Publication Date: 2022
Summary:
At the time we are writing this article, hundreds of thousands of delivery vehicles are getting ready to hit the road and travel across U.S. cities to meet the highest peak of demand for ecommerce deliveries during Thanksgiving, Black Friday, and the Christmas holiday season. This mammoth fleet will not only add vehicle miles traveled through urban centers but also increase parking congestion, battling with other vehicles for available curb space.
While the integration of road traffic data with modern navigation systems has seen huge developments in the past decade, drastically changing the way we, and delivery vehicles, navigate through cities, not as much can be said when it comes to parking. The task of finding and securing parking is still left to drivers, and largely unsupported by real-time information or app-based solutions.
Delivery vehicle drivers are affected by curb parking congestion even more than any other driver because delivery drivers have to re-park their vehicles not once or twice, but 10, 20, or even more times during a delivery route.
Our work, discussed in this article, focuses on improving delivery drivers’ lives when it comes to finding available curb space, improving the delivery system, and reducing some of the externalities generated in the process. We first describe what types of parking behaviors delivery drivers adopt when facing a lack of available curb parking, then we will quantify the cost of lack of available parking, estimating how much time delivery drivers spend circling the block and searching for parking. We then discuss how we can improve on that by creating the first curb availability information system – OpenPark.

 

Recommended Citation:
Dalla Chiara, Giacomo and Anne Goodchild. Giving Curb Visibility to Delivery Drivers. Intersections + Identities: State of Transportation Planning 2022, 134-143.
Article

Physics-Informed Machine Learning of Parameterized Fundamental Diagrams

 
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Publication: arXiv
Volume: 2208.0088
Publication Date: 2022
Summary:

Fundamental diagrams describe the relationship between speed, flow, and density for some roadway (or set of roadway) configuration(s). These diagrams typically do not reflect, however, information on how speed-flow relationships change as a function of exogenous variables such as curb configuration, weather or other exogenous, contextual information. In this paper we present a machine learning methodology that respects known engineering constraints and physical laws of roadway flux–those that are captured in fundamental diagrams– and show how this can be used to introduce contextual information into the generation of these diagrams. The modeling task is formulated as a probe vehicle trajectory reconstruction problem with Neural Ordinary Differential Equations (Neural ODEs). With the presented methodology, we extend the fundamental diagram to non-idealized roadway segments with potentially obstructed traffic data. For simulated data, we generalize this relationship by introducing contextual information at the learning stage, i.e. vehicle composition, driver behavior, curb zoning configuration, etc, and show how the speed-flow relationship changes as a function of these exogenous factors independent of roadway design.

Authors: Thomas MaxnerDr. Andisheh Ranjbari, James Koch, Vinay Amatya, Chase Dowling
Recommended Citation:
Koch, J., Maxner, T., Amatya, V.C., Ranjbari, A., & Dowling, C.P. (2022). Physics-informed Machine Learning of Parameterized Fundamental Diagrams.