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3 golden objects Minnesota Legislature

Office of the Legislative Auditor - Program Evaluation Division

Airport Planning


February 1993

In December 1988, the Metropolitan Council completed a lengthy study of the long-term adequacy of the Minneapolis-St.Paul International Airport (MSP). The study concluded that one new runway would probably be needed between 1993 and 1998 and a second new runway would probably be needed between 2003 and 2018. In addition, the Council's report said that there was a significant risk that, even with every reasonable capacity enhancement, the existing airport's capacity would be exceeded within 20 years. Finally, the report concluded that, despite the expected introduction of quieter aircraft, noise-induced stress around MSP would increase due to the growing frequency of flights.

Based on the study's findings and recommendations, the 1989 Legislature mandated a dual-track planning process which would simultaneously consider both expansion of MSP and construction of a new airport. The legislatively-mandated planning schedule will result in the Council and the Metropolitan Airports Commission (MAC) recommending a decision to the Legislature by mid-1996. The early years of this seven-year planning process have included these activities: revision of aviation forecasts, selection of a new airport search area, development of a 30-year plan for MSP, study of alternative plans for reusing MSP, and examination of alternative sites for a new airport within the search area. Much of the detailed economic, aviation, and environmental planning and analysis has not yet been done but is scheduled to be completed in time for a July 1996 recommendation to the Legislature.

Although the dual-track process is years from completion, the process has become quite controversial. This evaluation was prompted by legislative concerns about the technical adequacy of work already completed. In addition, some legislators questioned whether recent changes in the airline industry should prompt changes in the scope or timing of the dual-track process. This report examines the following general concerns about the planning process:

  • Is the process being conducted in a technically competent manner?
  • Is the process designed to be comprehensive and complete?
  • Is the process being conducted over an appropriate time frame?
  • Are any changes in the dual-track strategy needed at this point?
The report focuses mainly on aviation forecasts, noise analysis, economic analyses, and analyses of airport adequacy. The report does not examine the search area and site selection process.


Our main findings are that:

  • The Metropolitan Council's adequacy study overstated MSP's future capacity problems and inadequately analyzed future noise impacts.
  • The need for a new runway at MSP appears to be farther off in the future than initially forecast, but recent events suggest that delaying the dual-track planning process could be risky.
  • Some very good planning work has been done by both the Metropolitan Airports Commission and the Metropolitan Council, but the Council's consultants have used a number of questionable methods to reach key conclusions in past studies. As a result, we are concerned that the Council is not receiving adequate technical support from its consultants and staff.
  • The technical work done by both Council and MAC consultants needs to be more clearly presented and summarized for policy makers. In addition, the two agencies need to better coordinate their efforts so that they are using similar and appropriate methods of analysis.
  • With one major exception, plans for remaining dual-track studies seem reasonable but the test will be how well they are carried out. The important item missing from the planning process is work by the Council to ensure that the expansion options at MSP are not precluded by the future development of nearby properties.

Adequacy Study

In 1987, the Metropolitan Council recommended that the Legislature approve the undertaking of an airport adequacy study. The Council was appropriately concerned that insufficient attention was being paid to long-range airport planning in the face of strong growth in operations at MSP. However, we found that the Council's adequacy study was not carried out very well from a technical standpoint and that it overstated the probable capacity problems at MSP. In particular, we found that:

  • The forecasts of operations, particularly regional airline operations, were too high and were revised significantly downward by both the Council and MAC within 10 months of the passage of the 1989 Airport Planning Act.
  • The detailed methods used by the Council's consultant to determine airport adequacy are questionable.
  • The estimated operational delay times, which were used by the Council consultant to estimate the benefits of the dual-track process, greatly exceeded MAC's estimates and were so high for the then current year that Council staff and consultants should not have used them without further investigation.
  • The Council's conclusions about future airport noise annoyance were based on a technically inadequate study.

Timing of the Planning Process

Based on the revised forecasts made in 1990 and on the analysis of MAC's consultants, it could be argued that only one new runway will be needed before the year 2020. MAC's revised forecast and analysis suggest that the new runway would probably be needed sometime between 2005 and 2010. This scenario also suggests that some detailed planning work could be postponed. Completion of a detailed environmental impact statement (EIS) too many years prior to the need for capacity enhancement at either MSP or a new site could result in the need to redo some EIS work. In addition, it could be argued that the current financial condition of Northwest Airlines precludes any significant construction plans for the foreseeable future.

On the other hand, there are some good reasons not to delay the detailed EIS work. First, although the revised long-run forecasts made in 1990 seem reasonable, it is possible that the growth forecast to occur over 30 years could come earlier in the 30-year period than either MAC or the Council are now forecasting. For example, despite Northwest Airlines' financial condition, operations at MSP increased substantially in 1992 as Northwest consolidated more of its operations at MSP and its Detroit hub. Also, there are some indications that Northwest and its regional airline partners may wish to significantly increase regional operations at MSP. Even if Northwest's air carrier operations do not grow much after 1993, the potential growth in regional operations could make a new runway desirable around the year 2000. Thus, there is still a reasonable chance that the current timing of the dual-track process will be appropriate.

Second, there are pressures to complete the work that has begun. Residents near MSP would probably object to any delay because of a recent increase in noise around MSP as Northwest has added flights and delayed the purchase of quieter aircraft. Residents living in or near the Dakota County search area for a new airport might object to delaying the EIS since some believe that the search area is unacceptable for environmental and other reasons and that those issues should be resolved and not delayed.

Due to the considerable uncertainty facing any forecaster and the momentum of the dual-track process, we feel that any decision regarding the timing of the dual-track process is a difficult judgment call. As a result, this report does not recommend changing the timing of the dual-track process.

Technical Adequacy

Although we differ with MAC consultants and staff regarding some of their forecast assumptions and results, we generally found their work to be technically competent. The Council consultants and staff have appropriately attempted to provide a more comprehensive view of some issues than MAC and to summarize some of the broader implications of airport planning. This led the Council consultants during the adequacy study to attempt to make very precise statements about future airport adequacy, to examine the benefits and costs of capacity enhancement, and to look for an alternative noise measurement tool which would better capture the conflicting effects of increasing flights and quieter aircraft on noise stress.

However, we found that:

  • The Metropolitan Council staff and consultants have used a number of methods and reached some key conclusions which are questionable.

The serious problems we found with the technical aspects of Council studies or analyses were that:

  • The Council consultants used an inappropriate method for identifying when the airport is likely to become inadequate.
  • The benefit/cost analyses completed by Council consultants in 1988 and 1990 were based on extremely high estimates of current and future operational delays at MSP. As a result, the analyses overstated the benefits of capacity enhancement, which were measured. However, because the analyses did not include a number of other benefits and costs, it is unclear what a corrected analysis will show.
  • The noise analysis in the adequacy study was based on faulty statistical analysis and methods.
  • The Council staff and consultants have provided the Council with erroneous analyses of trends in hubbing activity at MSP (the use of MSP as a connecting point for travelers).

This does not mean that all Council airport planning work has had problems. Indeed, some very good work has also been done. However, we have serious concerns about the technical merits of some important Council analyses and feel that the technical weaknesses of the consultants and staff should be immediately addressed by the Council.

Presentation of Planning Work

A lesser, but also important, concern is that:

  • The forecasts and other technical work done by both the Council and MAC have not been clearly presented and summarized for policy makers.

This concern is both a general and a very specific one. In general, we found that both agencies could do a better job of summarizing the assumptions and conclusions of their technical work. While the dual-track process is open to public participation and characterized by many committees and public meetings, the many technical documents produced thus far are difficult to collect, read, and understand. The documents, such as those dealing with aviation forecasts and their implications for airport adequacy, are complex and not well summarized. We feel that better summaries of assumptions, historical trends, forecasts, and conclusions should be available to policy makers and interested public participants.

Some specific concerns we had were that:

  • The Council consultant's forecasts have not been itemized by type of aircraft operation in the main forecast report going to the Legislature. For the adequacy study, we could not find a breakdown by type of aircraft for the year 2018 in any report, even though the Council was predicting that regional airline operations would exceed the operations of major air carriers such as Northwest Airlines.
  • The MAC long-term comprehensive plan itemized $3 billion in noise mitigation costs as a cost of any MSP expansion plan even though there is general agreement that this estimate prepared by surrounding communities significantly overstates the costs of mitigation.

In addition, we also found that the Council's consultants and staff need to do a better job of documenting their analyses. For example, we found it was difficult to determine what assumptions were used in the Council forecasts because their consultants, in contrast to MAC's consultants, did not always write down all their assumptions and put them in one document. In addition, the Council consultant had difficulty in providing us with details of important analyses done in 1988 and 1989.

Future Planning Work

Our study also included a limited review of the plans for remaining work on the dual-track planning process. Overall, we found that:

  • It appears that the Council and MAC will be addressing all of the key issues which need to be addressed during the dual-track process.
  • In addition:
  • It appears that both agencies are interested in taking a strategic and flexible approach to addressing the region's future airport problems.

However, it is difficult to fully endorse the agencies' plans since they have not yet carried out the needed studies and we have serious concerns about how the Council staff and its consultants carried out some of their previous planning work.

One important piece of planning work that had been missing from the Council's agenda, until we brought it to the attention of the chair and staff, is that:

  • The Council had not done, or planned to do, the necessary planning work to protect the North/South runway option or other runway options at MSP.

The North/South runway is MAC's preferred option if capacity is added to MSP. That option would require acquisition of several hotels in Bloomington which are in the flight path or safety zone of the runway. We found that the Council staff assigned to the dual-track process were not aware of whether the Council had sufficient authority to prevent additional development in those areas. In addition, the Council and its staff had no plans to work with either the affected communities or the Legislature to make sure that any development would be compatible with that option or other runway options. This situation is in direct contrast with the new airport search area where the Council has direct statutory authority to limit development. Following our discussion of this concern with the Council chair and staff, the Council has begun to seek consultant and legal advice on how best to address the issue.


We have recommendations in the following four areas: 1) improving the technical adequacy of planning work, 2) improving the presentation and documentation of planning studies, 3) revising current forecasts and monitoring MSP aviation activity, and 4) protecting the North/South runway option or other expansion options at MSP.

Technical Adequacy

Based on our findings, we are particularly concerned that the Metropolitan Council have adequate staff and consultant support. While the Council staff assigned to the dual-track process are good general planners and facilitators of the planning process, we are concerned that the staff are not adequately equipped to evaluate the technical merits of analyses done by either the Council or MAC consultants. In addition, the Council's consultants, while providing some useful insights, have made some questionable judgments in methods and conclusions. We recommend that:

  • The Council should take prompt action to address these problems concerning its staff and consultant support.
  • The Council's action could include a number of options: 1) alter or supplement its staff resources, 2) alter or supplement its consultant resources, 3) use expert panels during later stages of study not just at the initial stage before a study is begun, and 4) make sure that their consultants and staff coordinate their efforts with MAC staff and consultants to ensure that the agencies are using similar and appropriate methods.

Presentation and Documentation

Both agencies need to improve their written presentation of technical reports. The Council's consultants also need to improve their documentation of analyses. We recommend that:

  • The Council and MAC staff and consultants should ensure that the principal conclusions of analyses and their key assumptions are summarized better for policy makers and the public.
  • The Council staff should ensure that their consultants provide the Council with adequate documentation of their methods, assumptions, and results.

Forecasts and Monitoring

While we take issue with the forecasts published in 1988, we found that the forecasting methods and results used in 1990 were generally more reasonable. Currently, the Council and MAC are once again in the process of revising the dual-track aviation forecasts. We recommend that:

  • The Council and MAC should consider revising downward their forecast of long-term enplanements because the hubbing ratio will probably not increase as forecast.
  • The Council and MAC should consider adjusting their long-term estimate of regional operations to a level between those forecast by the two agencies in 1990. They should also consider developing a better model for forecasting long-term regional airline enplanements and operations.
  • The Council and MAC should consider downward adjustments in the long-term forecasts of domestic air carrier operations.
  • The Council should drop the formal use of risk analysis but continue to emphasize the fundamental uncertainty of the forecasts.
  • As part of the annual monitoring process, Council and MAC staff should consult more closely with Northwest Airlines and its regional airline partners regarding their plans for future operations at MSP.

Although we do not recommend changing the timing of the dual-track process at this time, we recommend the following:

  • As part of the current forecasting process, the Council and MAC staff and consultants should assess the short-term prospects for operations growth and assess whether there is a sufficient risk that the region may need extra capacity before the year 2005.
  • The Council and MAC should closely monitor Northwest's financial condition and be prepared to recommend modifications in the dual-track process if warranted.

Protection of Development Options at MSP

The purpose of the dual-track process was to conduct a rigorous and comprehensive evaluation of options for adding airport capacity. The Council sought, and the Legislature provided, land use restrictions for new airport search areas. However, the Council staff has not researched the Council's authority to review and limit development which might jeopardize the use of a North/South runway at MSP -- MAC's preferred expansion option at MSP -- or other MSP development options. In addition, until recently, the Council staff had not planned any dual-track activities to address this concern. We recommend that:

  • The Metropolitan Council should have its staff report on whether the Council needs more authority or needs to be more proactive in working with affected communities to ensure that future development does not jeopardize viable development options at MSP.



Office of the Legislative Auditor, Room 140, 658 Cedar St., St. Paul, MN 55155 : or 651‑296‑4708