Peer Reviewed Publications
Abstract ↓
The importance of substitution patterns between public transit and carsharing has been discussed in prior literature. This study provides empirical evidence of significant interaction between the two modes. On November 24, 2015 the public transit rail system in Vancouver, Canada experienced a significant service disruption due to an unforeseen mechanical failure. This study exploits this event as a natural experiment and investigates to what extent the city's largest carsharing service was utilized as a substitute. Extensive carsharing vehicle location data are used to examine how the carsharing network responded to the transit service disruption. Empirical results show a dramatic increase in the use of carsharing vehicles during the transit outage, particularly in areas close to affected transit stations. Through regression analysis, the quantity of vehicle trips accommodated by the carsharing system in response to the outage is estimated to be approximately 800. There is clear evidence of extemporaneous substitution between public transit and carsharing, suggesting the two modes act as parts of an integrated network.
Abstract ↓
The choice to use bus transit over a rival mode of transportation is a consequence of many variables. The importance of bus service quality on mode share is often considered but rarely measured explicitly. This study presents a novel temporal data set of geolocated buses from New York City. The merger of locational vehicle data with public schedule data allows for the estimation of bus dependability across neighbourhoods. This study uses plausibly exogenous spatial variation in the introduction New York City’s Select Bus Service program to explore the relationship between the policy intervention, bus service quality and changes in commuter mode share. A propensity score matching procedure compares bus reliability and mode share in tracts that received Select Bus Service to a control group. A sizeable treatment effect is found. The policy intervention significantly increased service frequency and improved bus arrival reliability. Additionally, bus mode share amongst commuters in treatment neighbourhoods increased substantially. Select Bus Service was responsible for an increase in local bus mode share of 1.9 percentage points, with bus mode share in the median tract rising from 9.6% to 11.5%. Female commuters are found to be more responsive to the service improvements than males.
Abstract ↓
Expanding employment opportunities for citizens has become an increasingly central goal of public policy in the United States. Prior work has considered that the inability of households to spatially access jobs may be a driver of unemployment. The provision of public transportation provides a viable policy lever to increase the number of job opportunities available to households. Previous research has yielded mixed results regarding whether household location is an important factor in determining employment status. Several papers have identified mobility as a limiting factor for obtaining a job, particularly in regards to private vehicle ownership. The location of economically developed neighbourhoods and the citing of public transportation are conceivably codetermined, presenting an endogenous relationship. It is therefore unclear if public transportation access is actually contributing to neighbourhood job market outcomes. This paper will use the incidence of Hurricane Sandy striking New York City on 29 October 2012 and the resulting exogenous reduction in public transit access to particular neighbourhoods as a natural experiment to test for the effect of public transportation on employment outcomes. This study identifies a significant causal effect linking public transportation access to neighbourhood unemployment rates, particularly amongst subgroups dependent on public transit.
Abstract ↓
Carsharing programs have demonstrated a potential to significantly shift incentives with regard to private vehicle ownership. The advent of free-floating vehicle fleets has enabled providers to offer ubiquitous vehicle access in designated urban areas. The ability of users to choose where to drop off vehicles presents the possibility that the density of available vehicles in particular areas will be insufficient to supply a reasonable level of service to local residents. The current paper will use exclusive data on vehicle location from a free-floating carshare service that operates in ten U.S. cities. Analysis will relate the availability of vehicles to census tract demographics. Results show vehicles cluster in tracts that are disproportionately populated by residents who are educated, young, employed, and white. Carshare systems have received significant in-kind incentives from government to operate. The mobility benefits of free-floating carshare systems appear to accrue disproportionately to advantaged populations.
Other Publications
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Mobility, Economic Opportunity and New York City Neighborhoods
(w. Kaufman, Moss and Hernandez) 2015, The Rudin Center. |
Working Papers
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The Local Labour Market Effects of Light Rail Transit
Awards: Best paper by a graduate student, 2018 Transportation Research Forum Runner-up for best overall paper, 2018 Canadian Transportation Research Forum |
Abstract ↓
US cities have made large investments in light rail transit in recent years. Arguments in favour of light rail construction typically focus on enhancing workers' access to job opportunities. I analyse the labour market effects of light rail construction in four US metropolitan areas between 2000 and 2013. I propose a new instrumental variable to overcome endogeneity in transit station location. An inclination among transportation planners to extend light rail to the airport introduces a source of quasi-random neighbourhood assignment, enabling causal identification of neighbourhood effects. I find that light rail improves local employment outcomes. Local amenities cause workers to sort within a city, meaning that neighbourhood effects could be the result of endogenous sorting. To estimate distributional consequences and welfare effects, I propose and estimate a structural model of neighbourhood choice. The model is estimated with novel Google navigation data. I find that light rail systems fail to raise aggregate metropolitan employment because induced rent increases repel low skilled workers, displacing them to inaccessible locations.
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Getting High and Low Prices: Marijuana Dispensaries and Home Values
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Abstract ↓
Laws concerning marijuana have recently undergone liberalization in many North American markets. The changing legal environment has enabled the establishment of retail marijuana dispensaries. Local externalities generated by dispensaries may impact home values, particularly by influencing demand for the surrounding neighbourhood. Recent empirical evidence has found a positive effect of dispensaries on home values. I use unique data on 84 dispensaries and 62,000 repeat home transactions from Vancouver, Canada to estimate the effect of dispensaries on home prices. Historical Google Street View images are used to construct a longitudinal record of dispensary activity. I find that homes within 100 meters of a dispensary sell at a 3.7% discount.
Abstract ↓
Econometric analysis commonly proceeds under the assumption that a particular interaction between two right hand side variables is the only second order term that affects the dependent variable. We evaluate this assumption by replicating 31 regression results across 13 recently published empirical papers from a top economics journal and then augment the regressions to include more second order terms. The majority of replicated results are significantly altered when additional second order terms are included. We reject the null hypothesis that the excluded second order terms are jointly insignificant in 29 of 31 cases. In 17 of 31 cases the introduction of second order terms alters the result so that it no longer lies within the published 95% confidence interval.
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Going Nowhere Fast: Urban Mobility, Job Access and Employment Outcomes
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Abstract ↓
Providing fast transportation within cities is often considered as a way to improve labour market connections. This paper will quantify metropolitan level mobility with respect to home-work commuting. Commuter mobility in the US is found to vary substantially across metros in both levels and trends during the 2005-2014 study period. The impact of mobility on access to jobs is theoretically ambiguous due to mobility inducing urban sprawl. An instrumental variable method will exploit random variation in the political process governing transportation infrastructure funding. Results provide causal evidence that increased commuter mobility led workers to experience reduced local job density. Estimates fail to find evidence that commuter mobility improved labour market outcomes. Findings are consistent with increased commuter mobility exacerbating spatial mismatch through employment dispersion.
Abstract ↓
Cycling rates vary substantially across US cities and across neighbourhoods. Differences in geographic endowments are often cited as the cause for this variation. I estimate the role of natural endowments, particularly topography and climate, in determining the share of a metro's workers who cycle to work and the probability a particular worker chooses to cycle. I combine a US wide data set of commute flows with detailed elevation and climate data. Across US metropolitan regions, differences in climate explain 21% of the variation in bicycle commuting. Rain and extreme temperatures are found to deter cycling. The hilliness of a metro is not found to predict cycling rates. Within metropolitan areas, commuters who face shorter and flatter commutes are more likely to choose cycling. I find that elevation changes are less of a deterrent to cycling when the workplace is located downhill relative to the home. Overall, geography plays a small role in explaining cycling choice.