The Long-Range Transportation Planning Process: Complex Answers to the Wrong Questions

"It's tough to tell the future." So begins a report distributed by the Florida Department of Transportation (FDOT) as background for the 2020 Florida Transportation Plan. It goes on to note that, "Analyzing historical and current trends to forecast conditions 20 or more years into the future has been compared to throwing darts at a moving board under a strobe light. The dynamic nature of social, economic, and political activities in the United State and Florida creates too many uncertainties for foolproof forecasting."

In spite of the recognition of uncertainty by some, current methods and practices largely ignore its implications in the planning of future transportation facilities. As part of the recently completed State Transportation Policy Initiative, CUTR examined these issues and reported findings in a publication titled A New Strategic Urban Transportation Planning Process (CUTR, 1996).

The Planning Process

Metropolitan Planning Organizations (MPOs) are responsible for carrying out long range transportation planning, covering a period of at least 20 years, and for setting transportation priorities for urbanized areas. MPOs make use of a transportation planning process comprised of a series of sequential models to describe the interactions between land use, the transportation system, and travel.

After models have been calibrated with base year data, they are applied with forecast year land use and transportation system characteristics to derive forecast year performance. This basic process is used by MPOs across the nation. Based on economic and land use characteristics forecasted for the study area in some future year (generally 20 years), a long range transportation plan is produced. The plan is then staged so that early implementation projects are timed for consistency with the long range plan.

Change Cannot Be Predicted with Certainty

An underlying premise in this process is that forecasts can be made 20 years into the future. The reality is that the models are not very precise, and the inputs to the models are fraught with uncertainty. How precise can forecasting social and economic factors 20 years into the future be? Consider the state of the national economy 20 years from now, specifically population and employment. Assumptions need to be made about many factors--the possibility of war, major recessions, petroleum production, and immigration policy.

Consider then an individual state s share of the national growth. For Florida, consideration should be given to the future of Cuba and Haiti, tourist preferences, potential natural disasters, and availability of potable water. Beyond the state level estimates, growth increments in individual counties must be forecasted, which can be influenced by many factors unique to each county. Finally, growth estimates must be disaggregated into hundreds of traffic analysis zones in a given county. Clearly, the process is fraught with uncertainty. And yet, this is exactly what takes place every time a long range plan for an urbanized area is developed—an optimal response to a set of forecasts that will almost certainly not materialize as planned.

Forecast Performance

Some examples of past performance in transportation forecasts tell the story: In 1970, the Tampa Urban Area Transportation Study developed traffic forecasts for the year 1985. A comparison of the actual 1985 traffic volumes with the forecasts made in 1970 reveals that errors ranged from -78 percent to +281 percent for 87 different links. The average absolute link error was 57 percent—hardly the best estimates to be used for major capital planning purposes.

During the early 1980s, several forecasts were prepared of employment in the Tampa central business district (CBD). One projected that CBD employment would be 75,000 to 80,000 by the year 2000. In the mid-1980s, new forecasts were made. By then, it was clear CBD employment was not on track toward 80,000 by the year 2000; the new forecast was that employment would be in the 55,000 range by the year 2000 and would approach 90,000 by the year 2010. The reality is that, in the years since 1980, CBD employment has been very flat, falling in the 26,000-28,000 range in 1994. Unfortunately, these forecasts were the basis for major capital facility planning in the city for a decade.

Current Problems in Practice

Many problems with current transportation planning practice lead to poor or ineffective decisionmaking. The most significant problems include:

1. The inability to predict the future. Uncertainty exists in future demand, technology, costs, resource availability, and values. Imponderable and unpredictable events will shape the future in ways we cannot hope to anticipate.
2. Current travel demand models are limited in their ability to replicate the present, much less forecast the future.
3. Even if travel demand models were perfect, uncertainties in the input variables are enormous and, to a large extent, unpredictable.
4. Social and political bias is a strong contributor to errors in anticipating future events and to the willingness to deal with uncertainty.

Recommendations for a New Planning Process

The reality of uncertainty does not imply that planning should be abandoned. It does, however, demand that uncertainty be recognized and dealt with in the planning process. A number of recommendations can be made to better incorporate uncertainty into the planning process.

Develop a Strategic Vision--The process should begin with a strategic vision. Indeed, any meaningful planning process must have a vision of a desired outcome. Elected officials, as representatives of the general public, must be able to articulate a vision of what they want their community to be "when it grows up." The vision will necessarily be strategic--it will incorporate the general desired features, but will not specify precise details, as these must be responsive to the unknowable details of the future.

Identify Uncertainties—Once a strategic vision has been articulated, a classical strategic planning process should be undertaken to identify strengths, weaknesses, opportunities, and threats to reaching the desired outcome. The inclusion of this activity represents a radical departure from traditional planning practice, which evaluates all available information to estimate a single expected value for each variable. A critical element of the process should be the clear enunciation of all assumptions.

Plan for the Short Run, with an Eye on the Long Run--While it is not a major revelation that uncertainty increases with duration, surprisingly, it is a fact that is frequently ignored. It is recommended that the focus of transportation planning on the 20-year horizon be changed. Instead, the focus should be on current deficiencies, and on the five year horizon. Subsequently, based on the outputs of the five-year forecasts of socioeconomic and traffic conditions, the forecasts would be extended to a 10-year horizon. Similarly, at the conclusion of the 10-year forecast, an extension would be made to 20 years. Each step along the way, projects would be identified to meet transportation system deficiencies in each increment.

The emphasis would be on selecting the optimal short term plan, to meet the needs of the initial five-year period, but a sequence of improvements would be identified for each subsequent increment. In contrast to the current process, which is predicated on optimizing the response to a highly uncertain 20-year forecast, the recommended process is focused on optimizing responses in a shorter five-year time frame, with an eye on the long term.

Incorporate Independen Peer Reviews--The preparation of regional transportation plans, major corridor analyses, and major activity center studies should include an outside peer review, similar to value engineering reviews. The principal purpose of the peer review would be to review all planning process assumptions, both explicit and implicit, and to assure objective analysis.

Promote Flexibility--Once the reality of uncertainty is recognized, flexibility becomes paramount. In a future that holds unanticipated surprises, a high value should be placed on retaining future options. The planning process should therefore identify which options are foreclosed by a near term action.

Implement Major Capital Investments Incrementally--For every major transportation capital investment, an incremental implementation plan should be developed that undertakes usable portions of the major investment in a sequential program. Some of the most controversial transportation investments are major fixed guideway transit projects. The planning that has been applied to these systems reflects many of the identified pitfalls. Risks and uncertainties, particularly as they relate to future ridership and costs, have made it impossible to muster the political support to implement such systems. Instead of the "one-shot" long range picture of the desired system decades into the future, an incremental approach is recommended.

For example, express bus service using makeshift park and ride lots might be offered, making use of church parking lots or of under-utilized shopping center parking spaces. As demand increases, permanent park and ride facilities can be constructed.

As warranted by demand, high occupancy vehicle (HOV) facilities can be implemented, and preferential bus treatments can be constructed. As each of these actions is taken, based on ridership affirmation, political support for the next increment of investment will build. Ultimately, the addition of a guideway transit system can be justified, with the park and ride infrastructure already in place.

Hopefully, the implementation of this new strategic approach to transportation planning will allow planners and decisionmakers to recognize uncertainty, yet not be paralyzed by it; to move proactively toward the attainment of valued societal objectives, yet be prepared for the changes that cannot be predicted.

For further information or a copy of the report, contact STPI Project Manager and study author Ed Mierzejewski, mierzeje@eng.usf.edu.