A delicate balancing act reducing network congestion through TDM*

Explore • Pulse #7 • 4 MIN
By Julien Thèves

What happens when a metro or train system reaches maximum capacity and it’s no longer possible to extend the network or add more rolling stock? *Travel Demand Management (TDM) is all about improving the flow of public transport systems by adjusting travel demand. For large cities, this mass transit management solution could be a game‑changer.

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Cyberabad dreams

7 min

Travel demand management (TDM) is a mobility management concept that emerged in the United States in the wake of the oil crises of 1973 and 1979. To save energy and improve traffic flow on the roads, drivers were encouraged to leave their cars at home via ad campaigns, an adjusted public transport offer and various financial incentives, including tolls and fiscal measures. In recent years, TDM has become a key tool for enhancing the efficiency of existing mass transit systems. It focuses on the four R’s: “Reduce” (limit travel), “Re-time” (change travel times to avoid peak periods), “Re-mode” (choose an alternative mode of transport, such as walking, cycling or the bus), and “Re-route” (take a different route to get where you want to go).

Relieving peak-hour congestion

“TDM has gradually become a preferred solution for the world’s major cities, as they struggle to deal with recurring network congestion and pressure on their finances,” says Agnès Grisoglio, Transformation & Mass Transit Academy Director, SNCF. “With the support of the region, local communities and public transport authorities, the Transilien teams in Greater Paris are implementing TDM initiatives to cope with peak-hour demand, for example, or during maintenance and renovation work. We’re focusing on the lines, stations and times with the highest levels of demand, such as those serving the La Défense business district or the Plaine Commune cluster. Based on our knowledge of peak-hour usage, we regulate demand by encouraging passengers to travel earlier or later on weekday mornings and evenings. We also liaise with the businesses and universities that generate passenger traffic to help spread departure and arrival times over a longer period.” The TDM initiatives being implemented around the world are many and varied. In New York, suburban train tickets are cheaper during off-peak hours, while in Melbourne, passengers can travel for free before 7:15 am. Other cities are finding more creative ways to get passengers to travel outside peak times. Examples include a points system that offers cash rewards in San Francisco, and free noodles in Tokyo!

Changes driven by Covid-19

When the 2020-2021 health crisis made physical distancing a necessity, TDM played a key role in regulating traffic flows. In New South Wales, Australia, for example, the operator increased the discount offered to passengers travelling during off-peak times, from 30% previously to 50% at the height of the epidemic, between July and September. In Beijing, a trial booking system was introduced right at the start of the pandemic for metro users travelling between 6:30 am and 9:30 am on weekdays. “The health crisis proved that commuters do have the ability to adjust their travel times,” says Agnès Grisoglio. “We need to leverage these behavioural changes to enable passengers to travel more comfortably in the future, in trains that are less crowded and consequently more punctual.”

Preparing for anticipated surges in demand

In addition to day-to-day challenges and Covid-related imperatives, operators also have to deal with temporary surges in demand caused by major events — a frequent occurrence in large cities and one that needs to be prepared well in advance. Once again, TDM seems to be the most promising solution and is often the only one that’s viable. In 2012, with passenger traffic expected to increase by 30% during the Olympic Games, Transport for London (TfL) launched its “Keep London Moving” campaign aimed at encouraging passengers to adjust their travel habits. The campaign worked: one in every three passengers changed their habits and overall travel demand decreased by 5%. “Five percent might not seem like much, but it’s enough to restore capacity to the network and make it more robust, particularly when employment is highly concentrated in specific areas”, explains Agnès Grisoglio.

As for France, Île-de-France Mobilités and its partners — SNCF, RATP, the public authorities and the Games committee — are already taking action to make the Paris 2024 Olympics a success. For Agnès Grisoglio, the challenge is a formidable one. “We’re accustomed to using TDM for temporary surges in demand related to major events,” she says. “But the Olympic Games will be 40 times bigger than a football or rugby World Cup! We need to come up with a TDM solution that will enable the mass transit network to prove its solidity and efficiency, while meeting the travel demand generated by Olympic Games spectators as well as the day-to-day mobility needs of those who live and work in the Greater Paris region.”


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