Transportation Demand Management

Transportation Demand Management
A Study Paper by Rez.Nurt

Introduction
Modern efforts to solve the apparent disparity between urban transportation system supply and travel demand can be split into two categories, Transportation System Management (TSM) and Transportation Demand Management (TDM). TSM measures are designed to increase system efficiency through operational improvements, thereby increasing the demand that can be accommodated. TDM measures, on other hand, are designed to entice travelers to use higher occupancy modes, thereby reducing the number of vehicle trips that must be carried by the system.

Transportation Demand Management succinctly is described as being "the art of influencing traveler behavior for the purpose of reducing or redistributing travel demand." The primary purpose of TDM is to reduce the number of vehicles using highway facilities while providing a wide variety of mobility options for those who wish to travel. TDM aimed to reduce peak period automobile trips by either eliminating the trip, shifting it to a less congested destination or route, diverting it to a higher occupancy mode or time shifting it to a less congested period of the day. TDM strategies often worked in conjunction with TSM measures.

History of Transportation Demand Management
Although the acronym TDM has been in use only since the mid 1980s, the concept of demand management first appeared during World War II when drivers were urged to carpool and conserve gasoline. In 1974 the concept became institutionalized as part of Transportation System Management requirement promoted by join planning regulations set by the Federal Highway Administration and Urban Mass Transportation Administration (now the Federal Transit Administration).
TDM has assumed a significant role in federal and local transportation policies. TDM is stipulated explicitly in the Intermodal Surface Transportation Efficiency Act of 1994 (ISTEA); Clean Air Act Amendments of 1990; and numerous local traffic reduction ordinances, development agreements and transportation plans.
In the original regulation, no distinction existed between supply and demand management. Eventually however, TDM became viewed as a separate policy tool, distinct from capacity (supply) management. During the period since the late 1980s, TDM has acquired professional legitimacy and has assumed political viability, while TDM programs have become mainstream through regional ridesharing agencies, transportation management associations, employers, local ordinances and development agreements.

Strategies and Techniques
TDM measures can be categorized in a variety of ways depending on the researcher’s point of view. HC Park in 1989 developed the definition of 66 different TDM strategies into 6 categories, namely traffic constrains, public transportation improvements, peak-period dispersion, ride sharing, parking controls and land use techniques. One of more interesting categorizations was by Rosenbloom. He divided into 18 different techniques into the 4 categories of social, socio-economic, socio-technical, and technical approaches. Ferguson also categorized into 4 steps of the urban transportation planning process, namely trip generation, trip distribution, mode choice and route selection.
Essentially TDM measures are designed with at least one of three primary goals in mind, namely, increasing the use of alternative modes, discouraging the single occupant vehicle (SOV) mode choice, or shifting travel demand to off-peak times or alternate routes.

TDM may focus on:

1. Transportation System
Seems a natural focus for modifying travel behavior through TDM program implementation
2. Activity System (location and land use)
As indirect means of controlling travel behavior
3. Organizational framework (institutions)
As a means to an end and as a barrier to be overcome

TDM strategies include:

1. Public mode support
Publicly provided alternatives to single- occupant- vehicle travel, including services and facilities that encourage and support other travel modes.

2. Employer-based support
Private-sector programs and services that encourage employees to change their commuting practices. Strategies include incentives that make publicly provided travel modes more attractive, disincentives to solo commuting and employer management policies that offer employees flexibility in travel mode choices. At the employment site, typical TDM alternatives to single-occupant vehicles may include carpools and vanpools; public and private transit, including buspools and shuttles; and nonmotorized travel such as bicycling and walking.
TDM programs also may include alternatives that influence the times of day when travel occurs, or if it occurs at all on certain days. These efforts, which usually are referred to as "alternative work hours," include compressed work weeks, in which employees work a full-time, 40-hour week in less than five working days; and flexible work schedules, which encourage employees to shift their starting and ending times for the work day, which in turn shifts their commuting times to less-congested hours of the day.

3. Pricing
Taxing and pricing mechanisms that affect the cost of transportation and thereby provide monetary disincentives to some travel behaviors.

4. Telecommunications
Emerging demand-management solutions that are based on advanced telecommunications technologies. Telecommuting programs allow employees to work one or more days at home or at a "satellite work center", which is often closer to their homes and thus does not require a longer trip into the primary work location.

5. Land-use policies
Potentially the most effective long-term TDM strategies, which have the abilities to shape population density, urban design, land-use mix, travel needs and travel patterns.

6. Public policy and regulation
Restrictions and regulations that govern private vehicle use and provide political support and guidance to new institutional relationships.


TDM strategies include improvements in alternative modes of transportation; financial or time incentives for the use of these alternative modes; information dissemination and marketing activities to promote these modes; and supporting services that make the use of alternatives more convenient or that remove psychological impediments to their use.
Examples of TDM strategies in parking management include:
1. Financial/time incentives, for example preferential parking for rideshares, subsidies for transit riders, and transportation allowances;
2. Priority treatment for rideshares, for example, provision of preferential access and egress to parking lots; and
information and marketing, such as on-site availability of transit schedules, periodic prize drawings for rideshares; and guaranteed ride home programs.
3. Application of site or area-wide cost surcharges or subsidy measures designed to make the relative cost of single occupant vehicle use higher than that for high occupancy vehicles. A typical example of area-wide cost surcharges would be parking surcharges placed on employer and public parking lots that would provide a differential cost structure for single occupant vehicles versus rideshares.

TDM techniques are divided into the following four categories:

1. Stimulation of Alternate Mode and Efficient Mode Usage.
Promote alternatives to the automobile by encouraging persons to switch to other modes of travel such as transit, bicycles, or walking and efficient uses of automobiles
a.) Park-and-Ride service, Shuttle Systems, Pedestrian Systems, Employer Transit Subsidies, Bicycling
b.) High-Occupancy Vehicle (HOV) Lanes, Ride Sharing, Truck Traffic Restrictions

2. Alternate Work Arrangement
Reducing maximum demand through diversion of peak period to relieve many congested area. Congestion is often caused more by concentration of demand for travel within time, rather in space.
a.) Alternate Work Hours: altering the hours employees report to and leave the worksite, and/or the days on which they report to the worksite. Ex: Flextime, Compressed Work Week, Staggered Work Hours
b.) Telecommuting: allows employees to work at a location other than their conventional office

3. Travel Constraint
Discouraging the use automobiles, including strategies designed to either increase generalized cost of travel, or to restrict usage of portions of the transportation network. 4 ways : physical restriction, time penalties, regulatory controls, and pricing methods.
a.) Limiting on-Street Parking and off-Street Public Parking
b.) Allowing developers to provide fewer than the standard number of parking spaces in exchange for promoting other TDM activities, such as ride sharing and variable work hours
c.) Requiring Parking Permits for Residential Areas adjacent to business districts
d.) Increasing Long-Term (commuter) Parking Rates.

4. Land Use Planning
Essential element of any long term effort to reduce or slow the growth of VMT in an urban area.
a.) Controlling population density and development in areas served by transit
b.) Reducing the required building setbacks
c.) Requiring developer to provide bicyclists and pedestrian friendly environment
d.) Encouraging large employers to locate away from city centers and close to residential areas
e.) Encouraging the development of self sufficient towns

Case Studies
Pasadena, California, Local developer only Traffic Management Ordinances (TMOs)

Pasadena passed TMO in July 1986, making it one of the first communities in the nation to embrace the TDM concept as a planning tool and zoning measure within the overall structure of the local development approval process.
Pasadena’s TMO applies to new developments as well as facilities that increase their gross floor area (GFA) by 25 percent or more. Nonresidential developments projected to house 500 or more employees face additional requirement under the TMO. TMO also applies square footage of facilities that would put the development under the ordinance.

The ordinance targets travel impact associated with work trips attracted to new development. Its goals include encouraging the use of alternative modes as well as alternative hours of travel during peak commuting periods. The objective of ordinance is to achieve an average vehicle ridership (AVR) of 1.5, in conformity with concurrent regional air quality regulations, within 10 year time period. AVR is the ratio of total employee person trips divided by total commute vehicle trips attracted to the site.

Pasadena’s TMO is very specific in identifying TDM requirements associated with development projects covered by ordinance. Companies in new developments that anticipate employing 100 or more persons are required to do each of the following:
• Set aside at least 10% of all employee parking spaces for carpools.
• Provide bicycle-parking facilities with the ration 3 bicycles per 200 employees.
• Provide computerized ridesharing matching service through Commuter Computer, the regional ridesharing agency
• Operate commuter information center

For companies in new developments that anticipate employing 500 or more persons in addition to list above must do following:
• Submit a TDM plan to the city for approval
• Provide on-site employee transportation coordinator (ETC)
• Provide adequate access min 7’2” vertical clearances and set aside a minimum of 1 % of all employee parking spaces for vanpools
• Provide loading areas for carpools and vanpools at the primary access
• Provide improvements to bus stops

As off 1997, a total of 43 sites were affected by the ordinance, employing an aggregate total of 13,000 workers, or about 15 percent of the city’s total workforce.
A survey showed that about 28 percent of average employee participation rate affected by the impact of the ordinance to chose alternative modes of travel. It means 72 percent of all affected employees drove alone. The AVR equivalent of this employee mode split is about 1.27, slightly higher than regional AVR of 1.25.

Case Studies
Parking Management in Portland, Oregon.

Portland has one of the most comprehensive parking policies in supporting of TDM in the nation. Portland has good reputation for environmental awareness and a strong planning tradition, attested to by the existence of Urban Growth Boundary.
Portland’s parking policies have been designated to promote mixed-use development in a strong downtown, supporting regional transit and urban growth initiatives. Contrast to most jurisdictions, Portland specifies maximum parking requirements in downtown area with no more than 0.7 parking spaces per 1,000 square feet allowed adjacent to the light rail corridor’s transit mall and 1.0 parking spaces per 1,000 square feet further away from the mall. Public parking facilities in downtown area are owned by city and operated by the downtown business association.
Portland regulates on street parking in downtown area through an extensive metering program. Metered spaces within three blocks of public parking garage have a one-hour limit, while most have a three-hour limit.
Since 1991, Oregon’s statewide goal has been to reduce per capita parking by 10 percent and per capita vehicle miles of travel by 20 percent within the usual 20-year, long rang transportation planning time frame. The Oregon employee commute option rule aims 10 percent reduction in commute trips for employers with 50 to 100 employees and a 20 percent reduction for employers with more than 100 employees. The usual options of alternative modes of travel, parking management, telecommuting, and on-site services are being considered to achieve these goals.

References

Federal Highway Administration and Federal Transit Administration. U.S. Department of Transportation. Overview of Travel Demand Management Measures. Final Report. January 1994.

Ferguson, Erik. Transportation Demand Management. APA Journal Report 477. 1998.

Gakenheimer, R., Meyer, M. Urban Transportation Planning in Transition: The Sources and Prospect of TSM. APA Journal. January 1979.

Giuliano, Genevieve. Testing the Limits of TSM: the 1984 Los Angeles Summer Olympics. Institute of Transportation Studies. University of California.1988.

May, Adolf D. Demand-Supply Modeling for Transportation System Management. Transportation Research Record 835.

Taylor, C.J., Nozick, L.K., and Meyburg, A.H. Selection And Evaluation of Travel Demand Management Meausures. 1996

Weiner, Edward. Urban Transportation Planning in the United States: An Historical Overview. Prager Publisher. Westport, CT. 1999

http://www.dot.gov. Website for Departement of Transportation of the US.

http://www.bts.gov. Website for Bureau of Transportation Statistic.