Research

 Publications

Hands on the wheel, eyes on the phone: the effect of smartphone usage on road safety 

with Devi Brands and Francis Ostermeijer - European Economic Review. https://doi.org/10.1016/j.euroecorev.2022.104130 

We provide novel evidence on the effect of smartphone use on road accidents. We exploit variation in phone usage fees in the Netherlands following a change in European Union roaming regulations implemented in 2017. The growth rate of mobile data roaming increased substantially after the change, which allows us to estimate a difference-in-differences model where non-Dutch drivers from the EU are treated, while Dutch drivers serve as control group. Our results suggest that around 10% of vehicles involved in accidents can be explained by the use of smartphones, and that these accidents mainly happen on urban roads.

Inclusive roads in NYC: Gender differences in responses to cycling infrastructure

with Laila AitBihiOuali  - Cities. https://doi.org/10.1016/j.cities.2022.103719 

This paper tests whether and to what extent the implementation of bike infrastructure increases the propensity to cycle overall and by gender. We use large-scale Citibike data recording customer behaviours for New York city for years going from 2013 to 2019. We find that dedicated cycling infrastructure increases women’s participation in cycling by 4% to 6%. This corroborates the hypothesis that both genders are more likely to take a transport mode when it is safer, with a larger response for the subgroup of women. 

Risk taking and air pollution: Evidence from chess

with Jos van Ommeren. Published in 2021 in Environmental and Resource Economics. doi.org/10.1007/s10640-021-00618-1

Medical research suggests that particulate matter (PM) increases stress hormones, therefore increasing the feeling of stress, which has been hypothesised to induce individuals to take less risk. To examine this, we study whether PM10 increases the probability of drawing in chess games using information from the Dutch club competition. We provide evidence of a reasonably strong effect: A 10μg increase in PM10 (33.6% of mean concentration) leads to a 5.6% increase in draws. We examine a range of explanations for these findings. Our preferred interpretation is that air pollution causes individuals to take less risk. 

Urban air pollution and time losses: Evidence from cyclists in London

with Jos van Ommeren. Published in 2020 in Regional Science and Urban Economics.  doi.org/10.1016/j.regsciurbeco.2019.103504

We provide novel evidence of the immediate impact of air pollution on time delays in urban outdoor activities. We focus on ambient ozone, which is known to reduce lung capacity. We estimate its effect on cycling speed in London using several estimation strategies, and find that ozone reduces speed for concentrations above 20 ppb, which is far below the minimum threshold suggested by other studies. A 10 ppb increase in ozone concentration leads to a 0.3–0.4% reduction in cycling speed, despite that most cycling trips are short, so that exposure to ozone tends to be short. It seems plausible that ozone induces time losses of similar magnitude of other outdoor activities, such as walking. 

Do metro interruptions increase the demand for public rental bicycles? Evidence from Paris

Published in 2019 in Transportation Research Part A: Policy and Practice. doi.org/10.1016/j.tra.2018.10.018

This paper studies demand for public rental bicycles following local and temporary metro interruptions in Paris. I construct a unique data set by linking metro interruptions announced in Twitter communication by the Parisian metro operator to usage data on the Vélib’ PBS. I find that, as a direct consequence of a metro interruption, the consumption of bicycles within 100m of metro stations increases by 0.72 bicycles per hour per docking station on average, and with 1.54 bicycles per hour per docking station during the first 20 min; an increase of approximately 11% and 22% respectively. Due to their effects on demand, metro interruptions increase the probability of empty stocks at docking stations with 15%. The findings highlight that cycling is a local net substitute for metro service, and that public rental bicycles can alleviate time losses stemming from interruptions in public transport.

Working papers

• Urban road capacity, congestion, and accidents: evidence from bike lane expansions in New York City  (with Dan Graham, Jos van Ommeren, and Erik Verhoef)

Governments increasingly invest in cycling infrastructure. We focus on New York City and estimate the causal effect of bike lanes on traffic congestion and road safety. We employ a fixed effects approach, where we address sorting by cyclists and cars. Installing fully-separated protected bike lanes reduces the number of accidents involving cyclists by about 20%, mainly because of a reduction in accidents away from junctions. At the same time, adding a bike lane in a certain area reduces car speed by about 1% in the whole area. We find no evidence of overall car traffic volumes to be affected by bike lanes.