A simulation based large bus side slip and rollover threshold study in slope-curve section under adverse weathers

Area of Science:

• Vehicle Dynamics and Safety Engineering
• Road Safety and Transportation Engineering

Background:

• Adverse weather conditions (rain, snow, cross-winds) and road geometry significantly impact large bus safety on slope-curve sections.
• Understanding the combined effects of these factors is crucial for preventing sideslip and rollover incidents.

Purpose of the Study:

• To investigate the sideslip and rollover thresholds of large buses operating in slope-curve sections under adverse weather conditions.
• To determine critical operating speed thresholds for large buses based on varying road friction coefficients and environmental factors.

Main Methods:

• Field measurements were used to obtain road surface friction coefficients under different rainfall and snowfall intensities.
• Wind tunnel tests determined the six-component force coefficients of wind acting on large buses.
• TruckSim simulation platform modeled a three-dimensional road and large bus, simulating wind-rain/snow coupling effects.

Main Results:

• Sideslip was identified by a sudden change in lateral acceleration (0.15m/s² to 0.52m/s²).
• Rollover was critically determined by zero vertical reaction force on the inner tire (at road friction coefficient 0.8).
• Operating speed thresholds were established for various road friction coefficients under combined adverse weather conditions.

Conclusions:

• The study provides critical insights into the dynamic behavior of large buses under combined adverse weather stresses.
• Established speed thresholds offer theoretical support for implementing effective speed limits on slope-curve sections to enhance bus safety.