Reduction of Car Travel: Transportation Demand Management (TDM)

Case Study

Reduction of Car Travel: Transportation Demand Management (TDM)

Up until 1960s, public transportation had played a crucial role as major urban transportation. However, since 1970s a sharp rise in the number of personal cars coupled with continuous economic growth had caused severe traffic congestion. Transportation Demand Management (TDM), which emerged as a strategy to resolve such traffic congestion, could be seen as an alternative approach to optimize the transportation demand by changing and attuning the demand patterns for each transportation means and time slot, which broke away from conventional approaches including transportation policy focusing on supply-side policy.

Since the introduction of congestion impact fee system in 1990s, various types of TDM approaches have been implemented including Namsan tunnel congestion charge, the parking threshold, and mandatory charging of parking lot fees in 1990s and Weekly No-Driving Day Program and car sharing in 2000s on a gradual basis.

Case study city(ies)
Case study country(ies)

TDM has been designed to induce changes in individual’s decision on means of transportation, travel time, traffic volume and travel area by changing overall elements affecting individual’s decision making. Ultimately, TDM aims to resolve traffic congestion, change it into sustainable transportation system which leaves less negative impact on the environment and society and maintains the sustainability by changing the quantity and structure of transportation demand.


Seoul Metropolitan Government (SMG)


From 1970s to 1990s, Korea’s transportation policy was tuned to the supply side, with much emphasis on construction and expansion of road networks to make up for the absolute shortfall in capacity. In that period, gap between supply and demand widened as rapid economic development led to sharp rise in transportation demand.

The number of personal cars registered in Korea had risen eight fold to 2,075,000 units in 1990s from 249,000 units in 1980 but 20% of road expansion for the same period fell far short of meeting the explosive demand. For those reasons even during the 1990s tremendous amount of efforts had been made to expand facilities by promoting private investment in transportation and construction at the government level.

In Seoul alone, the number of registered cars had risen to two million units in 1995 from one million in 1990 in just five years. Although expansion of street networks had been continuously promoted due to a soaring rise in the number of cars, road supply failed to catch up with the demand. Therefore, traffic congestion in the downtown in 1980s had been part of daily routine and in the 1990s traffic congestion in the major arterial roads had become more serious. In order to provide traffic facilities, large-scale road constructions had been conducted including expanding urban arterial roads and interregional expressway network, connecting City of Seoul and new town.  


Despite such a massive road expansion, the traffic congestion aggravated even further due to a soaring rise in the number of personal cars even after 1990s, leading to a continuous slower travel speed in Seoul. Advanced cities across the world also shared the view that additional supply of traffic facilities alone would not solve traffic congestion. In line with the times, the SMG has introduced TDM since 1990s as a strategy to mitigate traffic congestion.

Smart Solution(s) deployed by the case
Results and Impacts

Travel Speed


Transport share of personal cars in Seoul has shown continuous drop since 1990s due to the TDM policy implemented in various ways while the share of public transport has steadily risen from 61% in 2004 to 66% in 2014. The average travel speed on major and downtown roads, in turn, has increased. In the early 2000s, the average travel speed in downtown Seoul was 22.4 km/h, rose to 26.4 km/h in 2013. A similar phenomenon has been observed in the outskirts of Seoul and on major arterial roads.


Air Quality


Seoul’s air quality has also improved thanks to the increased average travel speed, decreased transport share of personal cars, and increased share of public transport. The concentration of fine dust – a cause of respiratory diseases and a hotly debated social issue – was 60/ in 2004, higher than Seoul’s permissible level of 50/. However, the decrease in personal cars and other elements helped reduce the concentration each year, and by 2013 it had fallen to 44/.


Priority on Pedestrians in Urban Transportation Policy


As the TDM policy encouraged drivers to switch to public transport or walk, the city also began to shift its policy focus from cars to pedestrians. In line with this trend, Seoul created a “Walk-Friendly Seoul” by reducing the 4-lane Gwangjingyo Road to 2 lanes in 2007 and expanding the pedestrian walkway. In January 2014, the city created its first transit mall on Yonsei-ro. Many zones busy with pedestrians on weekends (e.g., Cheonggye Stream, Hongik University) were turned into pedestrian-only areas. The TDM policy has significantly helped Seoul become a more walk-friendly city.

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