Monte Carlo simulation was used to examine the mobility
differences between automobiles and multimodal transport with increasing
trip lengths (Fig. 2). The trip length in Euclidean distance
started at 0.4 km because it is the maximum acceptable walking
distance in general (Atash 1994). The difference between automobiles
and multimodal transport in short trips is so large that commuters
hardly consider multimodal transport until lengths of
2.5 km. Therefore, increasing multimodal transport utilization
for green transportation for trips less than 2.5 km is infeasible.
In addition, the mobility difference decreasing rate became insignificant
after 12.5 km. Therefore, the Euclidean distances of OD
pairs were categorized into three ranges: short (0.4–2.5 km),
medium (2.5–12.5 km), and long (12.5–20 km). The trip lengths
of important OD pairs in Taipei mostly pertain to short and medium
distances. The variation of MRT accessibility at origins and different
detour ratios of trips lead to the fluctuation of multimodal
mobility in the same trip length.