Predicting cellphone manipulation based on magnitude of speeding

OBJECTIVE: The current study was conducted to assess the relationship between speeding behavior and handheld cellphone manipulation on different roadway classes. METHODS: = 593,454 trips). We used negative binomial regression models to predict the cellphone manipulation rate based on the speed limit and an indicator for how fast the vehicle was traveling relative to that limit during free-flow travel. An interaction term between speed limit and speeding behavior was included with covariates for time of day, day type, and area type. Models for limited-access and primary/collector roads were estimated separately due to little overlap in speed limits. RESULTS: A 5 mph increase in speed relative to the limit was associated with an increase in cellphone manipulation, although the magnitude of this increase was nearly 4 times as great on limited-access roads as on primary/collector roads. Statistically significant interactions between speeding and speed limit showed that the relationship between speeding magnitude and cellphone manipulation rates was exacerbated on both road types when the speed limit was higher. CONCLUSIONS: Both the reduced complexity of higher speed roads and the tendency for some drivers to take multiple risks likely help explain why speeding and cellphone manipulation occur together. These findings could aid traffic law enforcement in identifying locations where enforcing speeding and handheld cellphone laws together would be most effective. Countermeasures that raise perceived roadway complexity may also reduce the likelihood of both phone manipulation and speeding.