Journal of Korean Society of Transportation ISSN:1229-1366(Print) 2234-4217(Online) 대한교통학회지

In April 2021, the Safe Speed 5030 policy was introduced nationwide to improve road safety on urban roads. The purpose was to lower the speed limit on urban roads to reduce the possibility of death or serious injury to pedestrians and other vulnerable road users. However, lowering the speed limit could increase the social cost by increasing vehicle travel time. This study attempted to analyze the change in travel time before and after implementing the 「Safe Speed ​​5030」 policy for arterial roads in Gangnam-gu, Seoul. To this end, the digital tachograph data of taxis were analyzed. The trajectory data of taxis that passed through road sections of Hakdong-ro 2.6km, Bongeunsa-ro 2.6km, Teheranro 3.1km, and Yangjaedaero 1.3km, were extracted, and they were classified into late night, morning, afternoon, and evening hours. Then the unpaired t-test was conducted to compare the travel time change before and after lowering the speed limit. The results show that there was no change in travel times in most road sections and time intervals except for the afternoon hours of Teheranro after the speed limit was lowered. However, it has turned out that the average delay increase at the intersection accounts for 94 seconds out of 109 seconds of the rise in the average travel time. This intersection delay should have resulted from the growth of congestion due to increased traffic volume after relaxing social distancing to reduce the spread of Covid 19. It means that the speed limit reduction on urban roads is unlikely to have impacted travel time or speed decrease contrary to the expectation. These results are consistent with the previous studies. Nonetheless, further studies need to be conducted to improve the reliability of the conclusion by expanding the temporal and spatial scope.