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Reducing Urban Speed Limits Decreases Work-Related Traffic Injury Severity: Evidence from Santiago, Chile

Eduardo Graells-Garrido, Matías Toro, Gabriel Mansilla, Matías Nicolai, Santiago Mansilla, Jocelyn Dunstan

TL;DR

This study tackles the problem of work-related transportation injuries in Santiago, Chile, by leveraging a decade of insurance-reported incidents (2012–2021) and a natural experiment created by the 2018 urban speed-limit reduction (60 km/h to 50 km/h). Using a Negative Binomial regression that controls for mode, time of day, and demographics, the authors find that the urban speed-limit law is associated with a substantial reduction in injury severity, quantified as about 4.26 fewer days of prescribed medical leave. The analysis reveals higher severity among motorcycles, bicycles, and pedestrians, a protective effect for women, and increasing severity with age, alongside temporal and rural/highway patterns that inform targeted safety strategies. The work provides policy-relevant evidence for speed-management interventions in Latin American cities, while acknowledging data limitations such as exposure missingness and the absence of fatal cases. Overall, the findings support incorporating speed moderation into urban planning to reduce work-related injuries and maintain productivity.

Abstract

Work-related transportation incidents significantly impact urban mobility and productivity. These incidents include traffic crashes, collisions between vehicles, and falls that occurred during commuting or work-related transportation (e.g., falling while getting off a bus during the morning commute or while riding a bicycle for work). This study analyzes a decade of work-related transportation incident data (2012--2021) in Santiago, Chile, using records from a major worker's insurance company. Using negative binomial regression, we assess the impact of a 2018 urban speed limit reduction law on incident injury severity. We also explore broader temporal, spatial, and demographic patterns in these incidents in urban and rural areas. The urban speed limit reduction is associated with a decrease of 4.26 days in prescribed medical leave for incidents in urban areas, suggesting that lower speed limits contribute to reduced injury severity. Our broader analysis reveals distinct incident patterns across different groups. Workers traveling by motorcycle and bicycle experience more severe injuries when involved in traffic incidents, with marginal effects of 26.94 and 13.06 additional days of medical leave, respectively, compared to motorized vehicles. Women workers tend to have less severe injuries, with an average of 7.57 fewer days of medical leave. Age is also a significant factor, with older workers experiencing more severe injuries -- each additional year of age is associated with 0.57 more days of medical leave. Our results provide insights for urban planning, transportation policy, and workplace safety initiatives.

Reducing Urban Speed Limits Decreases Work-Related Traffic Injury Severity: Evidence from Santiago, Chile

TL;DR

This study tackles the problem of work-related transportation injuries in Santiago, Chile, by leveraging a decade of insurance-reported incidents (2012–2021) and a natural experiment created by the 2018 urban speed-limit reduction (60 km/h to 50 km/h). Using a Negative Binomial regression that controls for mode, time of day, and demographics, the authors find that the urban speed-limit law is associated with a substantial reduction in injury severity, quantified as about 4.26 fewer days of prescribed medical leave. The analysis reveals higher severity among motorcycles, bicycles, and pedestrians, a protective effect for women, and increasing severity with age, alongside temporal and rural/highway patterns that inform targeted safety strategies. The work provides policy-relevant evidence for speed-management interventions in Latin American cities, while acknowledging data limitations such as exposure missingness and the absence of fatal cases. Overall, the findings support incorporating speed moderation into urban planning to reduce work-related injuries and maintain productivity.

Abstract

Work-related transportation incidents significantly impact urban mobility and productivity. These incidents include traffic crashes, collisions between vehicles, and falls that occurred during commuting or work-related transportation (e.g., falling while getting off a bus during the morning commute or while riding a bicycle for work). This study analyzes a decade of work-related transportation incident data (2012--2021) in Santiago, Chile, using records from a major worker's insurance company. Using negative binomial regression, we assess the impact of a 2018 urban speed limit reduction law on incident injury severity. We also explore broader temporal, spatial, and demographic patterns in these incidents in urban and rural areas. The urban speed limit reduction is associated with a decrease of 4.26 days in prescribed medical leave for incidents in urban areas, suggesting that lower speed limits contribute to reduced injury severity. Our broader analysis reveals distinct incident patterns across different groups. Workers traveling by motorcycle and bicycle experience more severe injuries when involved in traffic incidents, with marginal effects of 26.94 and 13.06 additional days of medical leave, respectively, compared to motorized vehicles. Women workers tend to have less severe injuries, with an average of 7.57 fewer days of medical leave. Age is also a significant factor, with older workers experiencing more severe injuries -- each additional year of age is associated with 0.57 more days of medical leave. Our results provide insights for urban planning, transportation policy, and workplace safety initiatives.
Paper Structure (19 sections, 5 equations, 9 figures, 1 table)

This paper contains 19 sections, 5 equations, 9 figures, 1 table.

Table of Contents

  1. Related Work
  2. Urban Mobility and Safety
  3. Spatial Analysis of Traffic incidents
  4. Impact of Speed Limit Laws
  5. Gender and Age Dynamics in Traffic Incidents
  6. Work-Related Incidents in Urban Contexts
  7. Context and Data
  8. Methodology
  9. Data Representativeness
  10. Exploratory Analysis
  11. Speed Limit Law Effects on Prescribed Medical Leave
  12. Results
  13. Data Representativeness
  14. Mode of Transportation and Event Severity
  15. Temporal Patterns
  16. ...and 4 more sections

Figures (9)

  • Figure 3: a) Monthly distribution of the number of crashes, collisions or falls. b) Histogram of the number of incidents concerning the number of medical days of leave. c) Mean number of prescribed medical days of leave per month, with mean value annotations before and after Chile's latest speed regulation law (August 4th, 2018).
  • Figure 4: Mode of transportation patterns. a) A boxplot of prescribed medical days of leave in crashes, collisions, or falls with respect to mode of transportation. The midline in each box represents the median for that category. Outliers are not displayed. b) Relative distribution of mode of transportation in incidents per year.
  • Figure 5: Incident distribution per day of the week (panel (a)) and period of the day as defined by the last travel survey (panel (b)).
  • Figure 6: Fraction of incidents per gender and age ranges (column-normalized).
  • Figure 7: Age trends in the number of medical days of leave due to incidents, disaggregated by gender. The band surrounding each trend line encodes the 95% confidence interval.
  • ...and 4 more figures