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Evolution of Alternatives - The Changing Face of Transportation Demand Management
WGI
10 min read
By Lisa Nisenson and Ravali Kosaraju, PE, PTOE
Transportation Demand Management (TDM) is a transportation planning approach that’s designed to reduce the number of single-rider vehicle trips into and around cities. TDM emerged from the dual oil crises of 1973 and 1979, both of which crippled the U.S. economy and caused widespread hardship. Initially, it was designed to alleviate oil consumption.
Eventually, the focus of transportation planners promoting TDM evolved from oil consumption to traffic congestion. Over the past 40-plus years, TDM has grown to be more about improving the quality of life for commuters and urban dwellers while at the same time making roads safer (and less aggravating).
Early approaches included the promotion of carpooling, as well as the development of light rail, the expansion of public bus systems, and, eventually, dedicated bus lanes. The idea was to get people out of their own personal vehicles to either ride with friends or use public transportation.
Today, TDM is a widely utilized planning approach that helps cities improve the performance of their existing transportation systems and infrastructure through:
- More efficient use of parking resources.
- Reduced peak-period traffic levels.
- Shifting traffic to off-peak periods.
- Alternatives to single-occupancy vehicles.
- Improved transportation accessibility.
How and Why TDM Has Evolved
In the beginning, TDM planners were working with a blank canvas, given the auto-centric focus of transportation in the United States. The challenge was that the United States had (and continues to have) a very well-established car-centric culture. Americans loved their cars, seeing them as a source of independence, status, and in many cases, reflections of their personalities. As a result, it wasn’t enough to just offer alternative transportation options. Planners needed to create strategies that would encourage commuters and travelers to leave their personal vehicles at home and use those alternative transportation offerings. Historically, employers have played an essential role in the success of TDM programs, and they still do. For instance, employers often offer Commuter Choice programs offering free bus passes, preferred parking or guaranteed rides home, or amenities like showers for bike commuters. Programs can offer any combination of the following: using transit, carpooling and vanpooling, biking and walking, and parking management. Commuter Choice is sponsored by the U.S. Department of Transportation and the Environmental Protection Agency, in conjunction with local and regional authorities, which work closely with employers to promote TDM programs. It’s a true government/business/community partnership.
How does Commuter Choice benefit businesses? These programs make it easier and more affordable for employees to get to work, which has a positive impact on employee satisfaction and morale. Likewise, companies’ open support for staff’s use of alternative transportation improves employee satisfaction with their jobs and employers. The best programs have an onsite TDM manager who is a constant presence in the company promoting alternative transportation options. Having an onsite manager also makes it easier to quantify a program’s success by measuring how expensive the program is and how it impacts staff transportation behavior.
One of the most important examples of the evolution of TDM was the creation of the Association for Commuter Transportation (ACT). ACT is a national advocacy and professional association comprised of TDM professionals promoting TDM initiatives, establishing best practices, and offering educational programs for other TDM professionals. Many regional and municipal governments, as well as universities, now also have their own Transportation Management Associations to coordinate activities, incentives, and policies.
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The evolution of TDM is reflected in how transportation professionals now view congestion. It’s now generally understood that, in many cities, congestion is occurring outside of traditional rush hours, a trend accelerated by post-pandemic work and commute patterns. Mobility management is also vital in growing urban areas as they mature from single-use districts to mixed-use downtowns. As such, TDM can’t focus solely on commute trips and must also address non-work trips. For instance, some cities, such as Boca Raton, Florida, now institute TDM through the site plan approval process, requiring real estate developers to include TDM programs in new developments.
Another important example of the evolution of TDM is its expansion beyond just modes of transportation. For instance, employers can help reduce congestion by promoting telecommuting, flextime, and alternative scheduling to reduce work trips into the office. During the COVID-19 pandemic, many companies discovered that their employees could work productively—sometimes more productively—from home. As we continue to emerge from the pandemic, this is a lesson that employers can put to good use in promoting TDM.
Finally, parking management has become a much more important element of TDM over the past 40 years. In fact, parking demand management is now a specialized subset of TDM. TDM-related parking measures include:
- Dynamic pricing.
- Reduced parking minimums.
- Parking unbundling (where the cost of parking is separated from the rent so carless households don’t have to pay for parking).
- Parking cash-outs (where a non-auto commuter is given the cash equivalent as free parking).
- Shared parking programs (where companies with alternative scheduling can allow multiple employees with different in-office schedules to share the same parking space).
- Alternative pricing strategies (where companies that no longer need parking five days a week/30 days a month pay only for days their employees do use parking spaces).
What Does Research Say About Effective TDM?
The effectiveness of individual TDM initiatives can vary based on context, level of investment, and the extent of mobility options. A region with robust transit networks will provide the best alternatives to driving, for instance. That doesn’t mean that TDM measures in communities with less robust transit systems are doomed to failure, though. There are still plenty of non-transit strategies, such as the introduction of micromobility (scooters, bikes, etc.) and flexible transit service can help increase access even in remote areas. Also, as stated earlier, employee sanctioned remote work and flextime can also promote mobility. The co-benefits of TDM initiatives can also be key. For instance, when commuters have access to Wi-Fi and desks when using transit, they can be more productive during their commutes. There are also safety benefits. As the U.S. grapples with reducing traffic-related casualties, studies show that transit travel can be 30 times safer by rail and more than 60 times safer when taking the bus.
Ultimately, each community and each TDM program is unique and needs to be created around local conditions and the habits and values of commuters and residents in those communities. That said, there are strategies that are likely to have an outsized impact on the success of TDM programs.
Efficient Parking Pricing and Management
Some communities are eliminating parking mandates and moving to demand-based pricing for downtown parking. This provides incentives for drivers not to commute in single-occupancy vehicles because the more cars that use parking, the more that parking will cost. The idea behind eliminating parking mandates is that parking then becomes market-driven rather than being mandated by regulations that try to anticipate future needs. This may not be the best approach for all cities, but it can benefit some.
Furthermore, unbundling parking within lease agreements removes the built-in penalty that carless tenants typically face. In this scenario, a resident pays for two types of real estate: the dwelling unit and a parking space. In effect, unbundling rewards residential tenants for not owning a car and commercial tenants for not commuting in their own personal vehicles.
Research shows that these parking-centric strategies can reduce vehicle owners by 5% to 15% and vehicle trips by 10% to 30%.
Ravali Kosaraju, PE, PTOE
Director of Mobility | WGI
Ravali Kosaraju P.Eng., PE, PTOE, is the Director of Mobility at WGI Inc. and a member of the IPMI Allyship & Equity Advisory Group.