4DA method of evaluating ride comfort during braking operation
  • Clarification of the relationship between ride comfort, deceleration and jerk on brake application
  • Proposal of a ride comfort evaluation method to optimize the ride comfort index
  •    In the areas of high-speed train operation and mass transit, it is important to increase transport efficiency by improving deceleration when trains stop at stations. To study brake patterns that do not impair ride comfort in operating trains with high deceleration, the RTRI performed tests to clarify the relationship between deceleration, jerk (i.e. the differential of deceleration) and ride comfort, and proposed a ride comfort evaluation method based on the findings.
       Through the above tests (implemented on the Yamanashi Maglev test line and other commercial service lines), the RTRI was able to clarify the above relationships in an area of unprecedented high speed (Fig. 1), and found that a difference of 0.1m/s3 in jerk significantly affected ride comfort. In tests simulating congestion rates of 100%, 150% and 250% as well as in fields tests on narrow-gauge lines, the RTRI obtained basic data related to the effects of congestion on ride comfort in braking operation. Higher congestion rates were found to increase the pressure working on passengers and cause a deterioration in ride comfort.
       In consideration of these findings, the RTRI proposed an index to evaluate ride comfort on braking based on deceleration and jerk (Fig. 2), with higher values representing a lower level of ride comfort. In regard to the trapezoidal brake pattern in Fig. 2, the RTRI analytically determined the values of deceleration and jerk that minimize the index for different combinations of brake starting speed and brake distance, and proposed this as a brake pattern to optimize the ride comfort on braking.

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