Working Papers

Working Papers:

Hoggin’ the Road: Slaughter Trucks Increase Crashes, Road Damage, and Vehicle Repair Employment (with Ben Blemings and Alex Scarcioffolo)

(Presented at NARSC 2021, AAEA 2022)

Read the paper here. 

While it has long been recognized that agricultural production comes with costs and benefits, its effects on transportation have remained under-studied. This paper estimates the effect of pork slaughterhouses on truck traffic and the subsequent consequences such as traffic crashes, road roughness, and auto repair employment. To recover causal estimates using two stage least squares, we exploit historic hog population as quasi-random variation in current pork slaughterhouse locations. We document historic hog data using a combination of historical data sources - recorded Census numbers from 1945 and maps which we process to produce data as far back as 1840. Using two-stage least squares, we find a one unit increase in slaughter volume increases truck traffic by 17.6%, fatal traffic crashes by 20.9%, and auto repair employment by 77%. Furthermore, estimates suggest that 95% of slaughterhouse volume on crashes is mediated by truck traffic and 100% of the effect on auto repair is due to trucks. These estimates are important for quantitatively assessing the optimal tax to address negative truck externalities resulting from slaughter and other industries.

Adaptive Traffic Control Systems and Urban Congestion: Evidence from Los Angeles (with Brad Humphreys and Dinushka Paranavitana)

(Presented at EEA 2022, SEA 2022)

Read the paper here. 

Traffic congestion represents a ubiquitous and serious urban problem around the world.  Policymakers frequently enact expensive policies like highway lane expansion, expansion of public transportation, and driving restrictions based on license plates to combat traffic congestion.  Adaptive Traffic Control Systems (ATCS) that dynamically alter the red/green cycle timing based on real-time traffic conditions represent an increasingly popular, low-cost approach to reducing congestion.  We analyze the impact of the installation of 4,700 ATCS signals in Los Angeles City in 2013 on local traffic congestion using the synthetic control method.  Results based on panel data from 96 California cities over the period 2010-2017 show that the ATCS signals did not reduce congestion in Los Angeles, but they did slow the increase in congestion relative to the increase in the synthetic unit, suggesting that ATCS signals impact traffic congestion but cannot effectively reduce it.

The Causal Effect of High Occupancy Vehicle Lanes on Commuting Times in California 

(Presented at Mid-Continent Regional Science Association (MCRSA) Meeting 2019; Scaled-Up Seminar at Susquehanna University 2019; North American Meetings of the Regional Science Association (NARSC) 2019; Eastern Economic Association (EEA) Meeting 2021)

Read the paper here. 

The effects of high occupancy vehicle (HOV) lanes studied from a causal perspective have been minimal in the economics literature. Knowing the impacts of these types of infrastructure projects is beneficial in terms of public policy and resource allocation. Using an instrumental variable (IV) approach to overcome the endogeneity problems associated with HOV lane location selection, this study aims to uncover the impacts of HOV lanes on commuters' time spent going to and coming home from work in California.  This paper finds that both having HOV lanes in workplace counties and living closer to HOV lanes cause increased commute times to and from work for commuters, lending credence to earlier works on road construction and traffic outcomes citing induced demand from increased road construction (Duranton and Turner, 2011)

Rough yet Smooth: Understanding the Importance of Mean Profile Depth for Highway Externalities (with Alex Cardazzi)

(Presented at SEA 2022)

Smoother roads improve ride quality and reduce negative traffic externalities.  Road quality is typically defined by a measure of smoothness, the International Roughness Index (IRI), though other road characteristics influence outcomes.  One factor that has been typically ignored by both academic literature and transportation departments is the relationship between a road segment's macrotexture and tire friction - how well a vehicle is able to "grip" to a road.  This study examines the role of Mean Profile Depth (MPD), a measure of a road's macrotexture, on traffic outcomes such as speed and crashes on California's Federal-Aid Highway System. Compared to previously estimated effects of IRI on traffic outcomes, estimates from an Instrumental Variable approach suggest that changes in MPD also result in economically significant magnitudes. Given these results, MPD plays an important, although currently reduced, role in cost-benefit analyses for selecting surface type.  Including MPD in the decision-making process could tip the scale towards using asphalt, relative to concrete, pavement.


Under Review:

Where the Rubber Meets the Road: Pavement Damage Reduces Traffic Safety and Speed (with Alex Cardazzi and Brad Humphreys)

(NBER-NSF Research Grant: Economics of Transportation in the 21st Century)

(Presented at NBER Virtual Conference 2020; Eastern Economic Association (EEA) Meeting 2021)

Read the NBER working paper here. 

Revisions requested at the Journal of Urban Economics

Road maintenance constitutes a significant component of public transportation spending at all levels of government. Formulation of efficient transportation infrastructure policy requires information about factors affecting road and traffic conditions. We generate the first causal evidence that decreasing pavement quality impacts vehicle crash rates and decreases average speed. Results from Instrumental Variable models using spatially and temporally disaggregated data from Federal-Aid Highway System (FAHS) roads in California show statistically and economically significant increases in vehicle crash rates and decreases in average vehicle speed caused by road damage. These impacts imply significant increases in social costs attributable to road damage. 

Media: Governing 

Unintended Consequences of the Appalachian Development Highway System on Mortality 

Read the paper here. 

(Presented at Southern Regional Science Association (SRSA) Virtual Conference Session 2020; Western Economic Association (WEA) Virtual Meeting 2020; Urban Economics Association (UEA) Virtual Meeting 2020; University of North Texas Economics Research Group (ERG) Virtual Seminar; North American Regional Science Council (NARSC) Virtual Meeting 2020; Southern Economic Association (SEA) Virtual Meeting 2020)

A growing literature aims to uncover the causal link between highways and economic activity. However, specific attention to federally funded rural roads and highways is sparse given implicit endogeneity concerns about road placement decisions for the sake of rural development and market exposure. This study examines the impact of the Appalachian Development Highway System (ADHS), one of the largest and most expensive federal infrastructure projects in the United States, on mortality outcomes in the region. Instrumental variable (IV) results suggest ADHS construction significantly reduced travel-time-sensitive mortality rates, such as heart disease and hypertension, in earlier decades of the sample. IV results also suggest the ADHS may be associated with increased mortality rates, notably accidents, in later decades of the sample. The additional cost caused by the ADHS in terms of mortality is estimated to be $24.2 billion dollars over the length of the sample. However, benefits such as improved travel times, employment, and income increases outweigh these costs.

Other Works in Progress:

Digitizing using QGIS: Active Learning in Urban Economics

Bars to Handlebars: Evaluating the Impact of Micromobility on DUIs (with Alex Cardazzi)

The Impact of Pavement Quality on Air Quality (with Alex Cardazzi and Brad Humphreys)

Using GIMP and QGIS to Digitize More Efficiently 

See the preliminary guide here.