| Summary |
I -JUNG Lu, 2006.07
Graduate Institute of Transportation Science, Tamkang University
After the operation of MRT system of Taipei city, the bus transit is still the major part of the public transit system, and plays a complementary role for feeder service in MRT corridor. At present there are 45 lines of feeder bus, which are planed by the Taipei city government to operate cooperatively with the MRT system. . Regarding to the setting of route length, the 8~10 kilometers of O-D trip are set as the principle for feeder bus. But this rule is only a experience judgment, and there is no theoretic base. In practice, some of the bus operators always try to lengthen the route or reduce the bus station in order to reduce the cost , that already lose the original meaning of providing feeder bus. Therefore, It is an importance common topic to build the reasonable principle of setting the length, and to considerate the carrier’s position to pursue the minimum cost for the government and the bus operator. .
In the position of regulation of government and the viewpoint of operator’s efficiency, the Translog cost function is employed to explore the cost efficiency of feeder bus under the minimum operation cost of route. In the building of cost function, the output is set the multiplier of the route length and frequency, where the frequency can be treated as a variable reflecting the level of demand. Moreover, in the cost model of route of bus, the attribute variable related to the characteristic of operation of route (i.e. length of route), and the related dummy variable (such as curve of length, the bus exclusive lane, and the number of bus stop) are utilized to explore the relationship among the cost and these variables. Finally, the economic concept of Minimum Efficient Scale (MES) is applied to estimate the ideal operation length of each route of MRT feeder bus in Taipei city. Beside, the changes in output and frequency are also further explored.
The 129 samples of route during the period of 2002~2004 years are used to establish the total cost function of MRT feeder bus. The empirical result shows that the bus exclusive lane has positive influence in operator’s cost, and the more number of stop will indeed increase the operation cost of route via the estimation result of the dummy variable of characteristics of route. In economics of scale, some of route of feeder bus posses the increasing or decrease return to scale, this means some of them can be adjusted to the optimal economics of scale by adjusting of frequency.
In the analysis of MES, this study adopts the Mean Absolute Percentage of Bias(MAPB) to measure the degree of difference between the original length of route and the ideal one(i.e. the estimated value of MES). The consequence of calculation indicate the average MAPB is about 21.?% in the total routes of feeder bus, and find there are average value of 2.16-3.97 kilometers of route lengths to be adjusted among each MRT line feeder bus. Beside, the optimal lengths of route of feeder bus are in the range of 14.5-18.99 kilometers for each MRT line, via the estimation of MES, under the average conditions of operation of MRT feeder bus of Taipei city. All of the above results can be referred as adjusting and regulating on length of route of MRT feeder bus for the bus operator and the government of Taipei city. |
