Lewis Lehe

University of Illinois, Urbana-Champaign | UIUC · Department of Civil and Environmental Engineering

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 Spe...

This paper incorporates two novelties into steady-state, macroscopic models of street-hail taxi service: (i) heterogeneous drivers; (ii) explicit treatment of a competitive rental market for medallions (the rights to cruise for passengers). When drivers vary only by reservation wage, issuing medallions raises every driver’s take-home pay, and the s...

This paper incorporates two novelties into steady-state, macroscopic models of street-hail taxi service: (i) heterogeneous drivers; (ii) explicit treatment of a competitive market for medallions (the rights to cruise for passengers). When drivers vary only by reservation wage, the social optimum requires subsidy, the second-best does not require me...

This paper considers static models of traffic in downtowns which can produce multiple equilibria. Models with one mode of travel can have one equilibrium in the light congestion regime, and multiple in hypercongestion. Models with two modes, which differ by occupancy, can have multiple in hypercongestion and in light congestion due to mode-switchin...

The dynamic spatiotemporal characteristics of queues at urban intersections are crucial to traffic operation tasks such as signal performance measure and signal optimization. This paper addresses the high time-resolution estimation of queue profile at urban signalized intersection using Extended Kalman Filtering (EKF) with data of connected vehicle...

This article introduces a database of bus stop spacings for 43 cities in the United States derived from GTFS files published in late 2019. Weighting each spacing by the number of times a bus traverses it, we produce distributions and summary statistics. The overall mean spacing is 313 meters. Las Vegas’ RTC has the widest mean spacing (482 m) and P...

For tolling in urban areas, the measured elasticity of demand with respect to money cost is much larger when tolls are introduced than when tolls are raised. This paper names this phenomenon “Large Elasticity at Introduction” (LEI). It has been observed in four of five cities with urban tolls: London, Singapore, Stockholm and Gothenburg. After desc...

Systems that depend on matching often exhibit scale economies, whereby increased participation leads to improved performance for all users. This paper examines the presence of such increasing returns to scale in carpool matching. Data from Scoop, a carpooling app, is used to demonstrate this phenomenon across various markets using regression. As th...

This paper considers the monetary and time costs of producing Findings (formerly Transport Findings ). After enumerating the journal’s expenses, we find the marginal monetary cost of an article is, on average, about $65, and that the journal incurs $1966 in fixed costs per year. Also, using data from a survey of Findings ’ reviewers and estimate of...

Static traffic models, in the tradition of Walters (1961), typically feature a "demand curve" giving the vehicle flow demanded for each unit travel time (inverse speed). Traditionally, the demand curve declines because people want to drive more as travel times fall. This paper proposes that the vehicle flow demanded can, instead, plausibly rise wit...

Studies of road pricing in which the Value of Time (VOT) varies among travelers suggest that road pricing benefits travelers with high VOT and hurts travelers with low VOT. This happens because, when a toll reduces congestion, only high-VOT travelers value the time saved more than the money cost. This paper uses a static traffic model with elastic...

Static traffic models, in the tradition of Walters (1961), typically feature a "demand curve" giving the vehicle flow demanded for each unit travel time (inverse speed). Typically, the demand curve declines because people want to drive more as travel times fall. This paper proposes that the vehicle flow demanded can plausibly rise with unit travel...

“Downtown congestion pricing” (DCP) is what this paper calls the practice of relieving congestion by charging tolls, or requiring the purchase of supplementary licenses, to drive in a city’s central areas. Five major cities have implemented DCP: Singapore, London, Stockholm, Milan and Gothenburg. This paper reviews the history of DCP, reporting on...

A growing consensus argues that minimum parking requirements (MPRs) make housing more expensive. This paper examines two claims from this discussion: (1) that MPRs discourage the construction of small units; (2) that the costs of building required parking are "passed on" to buyers and renters in the form of higher prices and rents. However, the mec...

This paper shows that severe congestion on streets controlled by traffic signals can be reduced by dynamically adapting the signal offsets to the prevailing density with a simple rule that keeps the signals’ green-red ratios invariant. Invariant ratios reduce a control policy’s impact on the crossing streets, so a policy can be optimized and evalua...

Currently, all downtown tolls are “access tolls,” meaning they charge for gross access to a zone, but tolls levied on distance-traveled are on the horizon. This paper shows how such tolls affect the distribution of trip lengths. A static model is presented in which travelers with potentially different trip lengths decide whether to drive into a dow...

This paper shows that severe congestion on streets controlled by traffic signals can be reduced by dynamically adapting the signal offsets to the prevailing density with a simple rule that keeps the signals’ green-red ratios invariant. Invariant ratios reduce a control policy’s impact on the crossing streets, so a policy can be optimized and evalua...

Land-use patterns are often the result of feedback effects in which one agent's decision both influences and is influenced by urban form. This paper argues that such feedback---of a positive or negative kind---could plausibly arise in the provision of off-street parking. A stylized model is used to illustrate feedback in the case of bundled parking...

This paper considers a signalized street of uniform width and blocks of various lengths. Its signals are pretimed in an arbitrary pattern, and traffic on it behaves as per the kinematic-wave/variational theory with a triangular fundamental diagram. It is shown that the long run average flow on the street when the number of cars on the street (i.e....

A growing literature exploits macroscopic theories of traffic to model congestion pricing policies in downtown zones. This study introduces trip length heterogeneity into this analysis and proposes a usage-based, time-varying congestion toll that alleviates congestion while prioritizing shorter trips. Unlike conventional trip-based tolls the scheme...