TY - JOUR
T1 - Safety in Numbers for Bicyclists at Urban Intersections
AU - Carlson, Kristin
AU - Ermagun, Alireza
AU - Murphy, Brendan
AU - Owen, Andrew
AU - Levinson, David
N1 - Publisher Copyright:
© National Academy of Sciences: Transportation Research Board 2019.
PY - 2019/6/1
Y1 - 2019/6/1
N2 - This study assesses the estimated crashes per bicyclist and per vehicle as a function of bicyclist and vehicle traffic and tests whether greater traffic reduces the per-vehicle crash rate, a phenomenon referred to as “safety in numbers” (SIN). We present a framework for comprehensive bicyclist risk assessment modeling, using estimated bicyclist flow per intersection, observed vehicle flow, and crash records. Testing a two-part model of crashes, we reveal that both the average of annual average daily traffic (AADT) over a 14-year period and the estimated daily bicyclist traffic (DBT) have a diminishing return to scale in crashes. This accentuates the positive role of SIN. Higher volumes of vehicles and cyclists lowers not only the probability of crashes, but the number of crashes as well. Measuring the elasticity of the variables, it is found that a 1% increase in the average of AADT across the time window increases the probability of crashes by 0.14% and the number of crashes by 0.80%. However, a 1% increase in the estimated DBT increases the probability of crashes by 0.09% and the number of crashes by 0.50%.
AB - This study assesses the estimated crashes per bicyclist and per vehicle as a function of bicyclist and vehicle traffic and tests whether greater traffic reduces the per-vehicle crash rate, a phenomenon referred to as “safety in numbers” (SIN). We present a framework for comprehensive bicyclist risk assessment modeling, using estimated bicyclist flow per intersection, observed vehicle flow, and crash records. Testing a two-part model of crashes, we reveal that both the average of annual average daily traffic (AADT) over a 14-year period and the estimated daily bicyclist traffic (DBT) have a diminishing return to scale in crashes. This accentuates the positive role of SIN. Higher volumes of vehicles and cyclists lowers not only the probability of crashes, but the number of crashes as well. Measuring the elasticity of the variables, it is found that a 1% increase in the average of AADT across the time window increases the probability of crashes by 0.14% and the number of crashes by 0.80%. However, a 1% increase in the estimated DBT increases the probability of crashes by 0.09% and the number of crashes by 0.50%.
UR - http://www.scopus.com/inward/record.url?scp=85067794621&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85067794621&partnerID=8YFLogxK
U2 - 10.1177/0361198119846480
DO - 10.1177/0361198119846480
M3 - Article
AN - SCOPUS:85067794621
SN - 0361-1981
VL - 2673
SP - 677
EP - 684
JO - Transportation Research Record
JF - Transportation Research Record
IS - 6
ER -