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2. ChatGPT for GTFS: Benchmarking LLMs on GTFS Understanding and Retrieval

Author

Devunuri, Saipraneeth, Qiam, Shirin, and Lehe, Lewis

Subjects
Computer Science - Information Retrieval, Computer Science - Artificial Intelligence, Computer Science - Computation and Language, Computer Science - Machine Learning
Abstract

The General Transit Feed Specification (GTFS) standard for publishing transit data is ubiquitous. GTFS being tabular data, with information spread across different files, necessitates specialized tools or packages to retrieve information. Concurrently, the use of Large Language Models(LLMs) for text and information retrieval is growing. The idea of this research is to see if the current widely adopted LLMs (ChatGPT) are able to understand GTFS and retrieve information from GTFS using natural language instructions without explicitly providing information. In this research, we benchmark OpenAI's GPT-3.5-Turbo and GPT-4 LLMs which are the backbone of ChatGPT. ChatGPT demonstrates a reasonable understanding of GTFS by answering 59.7% (GPT-3.5-Turbo) and 73.3% (GPT-4) of our multiple-choice questions (MCQ) correctly. Furthermore, we evaluated the LLMs on information extraction tasks using a filtered GTFS feed containing four routes. We found that program synthesis techniques outperformed zero-shot approaches, achieving up to 93% (90%) accuracy for simple queries and 61% (41%) for complex ones using GPT-4 (GPT-3.5-Turbo)., Comment: 22 pages, 8 figures, 1 table, Public Transport

Published
2023

3. Scale Effects in Ridesplitting: A Case Study of the City of Chicago

Author

Liu, Hao, Devunuri, Saipraneeth, Lehe, Lewis, and Gayah, Vikash V.

Subjects
Statistics - Applications
Abstract

Ridesplitting -- a type of ride-hailing in which riders share vehicles with other riders -- has become a common travel mode in some major cities. This type of shared ride option is currently provided by transportation network companies (TNCs) such as Uber, Lyft, and Via and has attracted increasing numbers of users, particularly before the COVID-19 pandemic. Previous findings have suggested ridesplitting can lower travel costs and even lessen congestion by reducing the number of vehicles needed to move people. Recent studies have also posited that ridesplitting should experience positive feedback mechanisms in which the quality of the service would improve with the number of users. Specifically, these systems should benefit from economies of scale and increasing returns to scale. This paper demonstrates evidence of their existence using trip data reported by TNCs to the City of Chicago between January and September 2019. Specifically, it shows that increases in the number of riders requesting or authorizing shared trips during a given time period is associated with shorter trip detours, higher rates of riders being matched together, lower costs relative to non-shared trips, and higher willingness for riders to share trips., Comment: This paper has been accepted for publication in Transportation Research Part A: Policy and Practice

Published
2023
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4. Bus Stop Spacings Statistics: Theory and Evidence

Author

Devunuri, Saipraneeth, Qiam, Shirin, Lehe, Lewis, Pandey, Ayush, and Monzer, Dana

Subjects
Statistics - Methodology, Physics - Physics and Society
Abstract

Transit agencies have been removing a large number of bus stops, but discussions around the bus stop spacings exhibit a lack of clarity and data for comparison. This paper proposes new terminology and concepts for statistical consideration of stop spacings, and introduces a python package and open-source database which uses General Transit Feed Specification data to derive real-world stop spacing distributions, Comment: 18 pages, 5 tables, 7 figures

Published
2022

17. Zone Pricing in Theory and Practice 

Author

Daganzo, Carlos F and Lehe, Lewis

Subjects
congestion, pricing, zone pricing, tolls, economics
Abstract

Amid growing recognition of the costs of downtown congestion and scarcity of revenues for new roads, congestion pricing for downtown areas -- a practice we call “zone pricing” -- has begun to receive wide attention. From 1975-2003, zone pricing failed to spread beyond Singapore, but by the 2000’s technological advances had made the practice more widely practical. Now London, Stockholm, Milan and Gothenburg have schemes of their own, and zone pricing is on the agenda in many world cities. The research summarized in this report has sought to advance practical knowledge of zone pricing in several ways. First, we have created a very detailed, scholarly history of zone pricing, covering the circumstances under which cities have implemented zone pricing, what technologies have been used and what results these cities have obtained. Second, we investigated the theory of “usage tolls.” A drawback of all tradition zone pricing systems is that, for practical reasons, they fail to charge different tolls to drivers who use the network to different degrees: someone who enters the downtown and immediately parks pays the same toll as someone who circles for an hour. But with new technology it will be possible to charge drivers for some index of road use, such as how far or how long they travel inside the network. Our research highlights two major advantages of usage tolling: (i) it can reschedule trips in optimal ways; (ii) it can discourage long trips -- such as those traveling across the downtown between points outside -- from happening by car in the first place. In both cases, an interesting result is the added precision of usage tolls means congestion reduction can be accomplished while charging drivers relatively little. We cite this as a political advantage that will help make zone pricing more palatable.

Published
2016

19. Inclusionary Zoning in a Monocentric City

Author

Lehe, Lewis

Subjects
Zoning, Regulation, Housing costs, Price controls, Affordability
Abstract

To show how inclusionary zoning alters development, the author finds the most profitable housing design to build on vacant lots at each location in a monocentric city under different regulatory regimes. Section 1 sets up the model by specifying renter's preferences, geography and building parameters. Section 2 solves the developer's profit-maximization problem at each location under each regime. Finally, in Section 3, a numerical simulation confirms the effects predicted by theory and gives a picture of their magnitude.

Published
2014

30. Aspatial models of zone pricing and parking

Author

Lehe, Lewis

Subjects
Civil engineering, Transportation
Abstract

It is often practical to collapse spatial information about a transportation system into aggregate variables related by an aspatial model---that is, a model in which individual interactions and directions of travel are not explicitly accounted for. This dissertation brings aspatial modelling to bear on two topics: downtown congestion pricing, referred to as ``zone pricing,'' and parking policy. Regarding zone pricing, a survey of the history of zone pricing shows that all existing systems fail to toll vehicles according to their use of the downtown network. To explore whether it would be advantageous to charge higher tolls to travelers who travel farther within the network, a static traffic model with probabalistic choice and variable trip lengths is proposed. Distance-based tolling turns out to be more socially efficient than charging all travelers the same price, but it leaves drivers themselves worse off since most of the welfare gains are converted to toll revenues for the government.Regarding parking, the thesis considers the idea of a ``feedback loop'' among landowners' uncoordinated decisions about how much off-street parking to provide on their parcels, when parking competes with floorspace as a use of land. One landowners' decision affects others' via two opposing channels. First, crowding: when there is too little off-street parking, on-street parking becomes crowded, making off-street parking relatively more valuable. Second, accessibility: when floorspace takes the place of off-street parking, the neighborhood becomes walkable through its higher density, making floorspace more valuable. A stylized model of development decision-making shows that each force leads to positive or negative feedback, resulting in multiple equilibria and counterintuitive results from policy.

Published
2016

39. The Seen and the Unseen En Scene: Visual Representations of Economics

Author

Lehe, Lewis James and Lehe, Lewis James

Abstract

Recent developments in economic theories of voter behavior have questioned the assumption that voters are rational. This paper analyzes how visual representation—in media and in thought—can engender misconceptions about political economy and preclude remedies to these misconceptions. I review Michael Moore's 1989 comedy-documentary Roger and Me, which treats layoffs at General Motors plants in Flint, Michigan, as well as "The Broken Window" from Frederic Bastiat's essay "The Seen and the Unseen." I argue linear narrative and the use of images as evidence undermine the consideration of the opportunity costs and widely-distributed effects of economic phenomena and thereby enhance the case for make-work.

Published
2010

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