Standard freeway merge designs support safer driver behaviour compared to taper designs: a driving simulator study

Area of Science:

• Transportation Engineering
• Human Factors in Driving

Background:

• Road geometric design standards offer options for freeway lane reduction merges.
• Taper designs are less common and require justification, with limited research comparing them to standard designs.

Purpose of the Study:

• To compare the driving performance and safety of standard versus taper freeway merging designs.
• To evaluate the impact of varying heavy vehicle compositions on driver behavior during merges.

Main Methods:

• Utilized a driving simulator to assess driver performance.
• Analyzed behavioral parameters including mean speed, acceleration, standard deviation of acceleration/deceleration, and lane changes.
• Employed multivariate analysis of variance (MANOVA) and repeated measures ANOVA for statistical comparison.

Main Results:

• The standard design was perceived as safer than the taper design.
• Drivers exhibited greater discomfort and behavioral disturbances with the taper design, particularly at moderate heavy vehicle percentages (15%).
• Significant differences in driver behavior were observed between the two designs and across different heavy vehicle compositions.

Conclusions:

• The standard freeway merging design is generally more favorable and safer than the taper design.
• The presence of moderate heavy vehicles significantly impacts driver behavior and discomfort during merging maneuvers, especially with taper designs.