Experimental Investigation into Driver Behavior along Curved and Parallel Diverging Terminals of Exit Interchange Ramps

Abstract

Current design manuals provide guidance on how to design exit ramps to facilitate driving operations and minimize the incidence of crashes. They also suggest that interchanges should be built along straight roadway sections. These criteria may prove ineffective in situations where there is no alternative to terminals being located along curved motorway segments. The paper investigates driving behavior along parallel deceleration curved terminals, with attention paid to the difference in impact between terminals having a curvature which is the same sign as the motorway segment (i.e., continue design), and those having an opposite curvature (i.e., reverse design). A driving simulation study was set up to collect longitudinal and transversal driver behavioral data in response to experimental factor variations. Forty-eight drivers were stratified on the basis of age and gender, and asked to drive along three randomly assigned circuits with off-ramps obtained by combining experimental factors such as motorway mainline curve radius (2 values), terminal length (3), curve direction (2), and traffic conditions (2). The motorway radius was found to be significant for drivers’ preferred speed when approaching the terminal. Terminal length and traffic volume do not have a significant impact on either longitudinal or transversal driver outputs. However, the effect of curve direction was found to be significant, notably for reverse terminals which do not compel drivers to select appropriate speeds and lane change positions. This terminal type can give rise to critical driving situations that should be considered at the design stage to facilitate the adoption of appropriate safety countermeasures.

Alternative Horizontal Markings along Curved Exit Ramp Terminals to Improve Driver-Safety-Related Performance

“…While traffic volume did have a slight impact on the lateral behavior of drivers, it was only at the beginning of the ramp curve (SC) as evidenced in Table 2 ( LP SC,3000 − LP SC,1000 = 0.075 m, p = .042). The results are in line with those obtained by Portera and Bassani: traffic volume on the motorway has no impact on the LP of the vehicle at the end of the terminal (TS) ( 24 ).…”

“…Figure 5 shows that female (F) drivers drove at lower speeds (S) than males (M) (S TT,F 2 S TT,M = 211.58 km/h, p = .003; S TS,F 2 S TS,M = 210.43 km/h, p = .009; S SC,F 2 S SC,M = 28.63 km/h, p = .009). This result is in line with the findings of Portera and Bassani, and Oltedal and Rundmo, who stated that male drivers are more willing to take risks than female drivers (24,54).…”

“…LMM in Table 2 also revealed significant differences in speed along the two ramp terminal connection types (i.e., continuous versus reverse). The geometric difference between the two CTs influenced driver longitudinal behaviors as confirmed by Portera and Bassani ( 24 ). This factor significantly affects speed at the TS (terminal end) section with the revese design where drivers arrived at a higher speed than they did on a continuous one ( S TS,R − S TS,C = 5.72 km/h, p < .001).…”

“…Recently, Portera and Bassani investigated driver behavior along the curved diverging terminals of exit ramps ( 24 ). They found that the direction of the exit ramp curve with respect to the curvature of the motorway has a strong impact on longitudinal and transversal driver behavior.…”

Adapting V ISA Technology: Driver Behaviour along Interchange Ramp and Merging/Diverging Terminals

“…The road elements were design as per Italian geometric design standards for highways and streets (MIT, 2001;MIT, 2006). The motorway cross-section offered two lanes per direction, having lane width of 3.75 m and a right shoulder width of 3.00 m (for more details, please see Portera and Bassani, 2021). Safety barriers were placed along both edges of the road section throughout the alignment (i.e., interchange ramps, motorway, and two-lane highway) which provides the specific ASD values while negotiating curves (Lioi et al, 2022).…”