title: Driver performance approaching and departing curves: driving simulator study.
abstract: OBJECTIVE
  This article reports the outcomes of a driving simulator study on the driver performance approaching and departing curves. The study aimed to analyze driver performance in the tangent-curve-tangent transition and verify the assumption of constant speed in a curve that is commonly used in the operating speed profiles; test whether the 85th percentile of acceleration and deceleration rates experienced by drivers and the acceleration and acceleration rates obtained from the operating speeds are equivalent; find the explanatory variables associated with the 85th percentile of deceleration and acceleration rates experienced by drivers when approaching and departing horizontal curves and provide predicting models of these rates.
  
  
  METHODS
  A driving simulator study was carried out. Drivers' speeds were recorded on 26 configurations of the tangent-curve-tangent transition of 3 2-lane rural roads implemented in the CRISS (Inter-University Research Center for Road Safety) driving simulator; 856 speed profiles were analyzed.
  
  
  RESULTS
  The main results were the following: The simplified assumption of the current operating speed profiles that the speed on the circular curve is constant and equal to that at midpoint can be considered admissible; The 85th percentile of deceleration and acceleration rates exhibited by each driver best reflect the actual driving performance in the tangent-curve-tangent transition; Two models that predict the expected 85th percentile of the deceleration and acceleration rates experienced by drivers were developed.
  
  
  CONCLUSIONS
  The findings of the study can be used in drawing operating speed profiles that best reflect the actual driving performance and allow a more effective safety evaluation of 2-lane rural roads.
authors.affiliation: a Roma TRE University , Department of Civil Engineering , Rome , Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Bella
mesh_terms: D000054:Acceleration; D000328:Adult; D001334:Automobile Driving / Q000523:psychology*; D003198:Computer Simulation; D003654:Deceleration; D004779:Environment Design / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012449:Safety; D013647:Task Performance and Analysis; D055815:Young Adult