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OD Estimation and Application Using Taxi DTG Data

Sun-Gwan KimㆍHyeon-Gyun Ki

Seoul has completed the installation of Digital Tacho Graph (DTG) onto all taxis in 2015. Although the DTG data is highly reliable data that reflects the use of taxis realistically, its use has been limited to checking traffic volume at the destination of passenger plane due to missing and erroneous spatial information and the fact that it is not installed in other areas except for Seoul. This study reviews the ways to utilize DTG data in the preparing statistics on taxi traffic volume as DTG data has become more stabilized gradually.

The number of DTG for Seoul taxis ranged from 1.1 million to 1.2 million per day. The amount was 1,273,971 in 2015 but it has been reduced by 1,159,775 daily in 2018. The data error rate has been gradually lowered from 9.2% in 2015, 7.2% in 2016, 6.5% in 2017 and 6.2% in 2018, suggesting that data has been stabilized. Among the types of error, the missing information about getting off accounted for the highest portion ranged from 3.4 to 6.1%. In particular, that type of error accounts for more than 50% of all error in terms of numbers. It is followed by missing information about getting on, and missing information about getting on and off. It is found that 1.0% ~ 1.2% of taxis’ operating area is outside of Seoul.

As a result of comparison between DTG OD and Taxi OD, the DTG OD showed 1.91 million traffic volume while taxi OD showed 2.12 million as of 2016, showing 9.7% of difference. The distribution by district level is very similar for DTG OD and taxi OD, but in some district, internal traffic volume ratio of taxi OD is found to be lower than that of DTG OD.

Since the DTG is currently installed on taxis in Seoul, scenarios were established for correction to make sure that DTG OD for traffic in Seoul and total taxi OD distribution. After the correction, the differences of traffic volume was reduced from 15.5%~12.7% to 9.1%~ 1.3%. The corrected value was used for the establishment of taxi OD in 2018.