Friday, December 8, 2006
Experts disagree on ridership
Honolulu HI - The Honolulu Advertiser had a relatively interesting article regarding projected ridership numbers for the proposed rail line that the city is trying for. It helps prove something I have long held was the case and that is that the projected ridership numbers that are generated for a proposed project are nothing more than a wild guess which favors the project in question.
Two University of Hawaii professors are currently battling it out with one saying the City's projection is actually on the conservative side while the other saying the projection is fatally flawed. Why doesn't this surprise me?
The problem stems from the use of past and present ridership data for the Honolulu area which appears to be skewed to the high side by as much as 21%. Again, why doesn't this surprise me?
There are many calculations that go into projected ridership numbers. While the formula for coming up with the numbers work in theory, the problem lies in the data which is input into the formula. All too often, falsified or inaccurate numbers are plugged in to the calculation from numbers supplied by the entity which wants the project in the first place. This results in a skewed projection being calculated.
Professor Karl Kim, who claims the projection is on the conservative side, states he reviewed the report from the City and found the information accurate and reliable. One big question begs to be asked of Professor Kim - Did you review the raw data?
The answer is probably not. If he did, he would have been questioning the data much as his colleague, Professor Panos Prevedouros is doing. The prime giveaway to the fact that the past and present ridership numbers were bad would be the wide variations in actual ridership versus the numbers used in the study.
This situation is not unique. Sadly, it is all too common. Transit systems routinely massage the ridership numbers different ways to enhance or detract from the actual ridership totals for reporting purposes. Too often these massaged numbers are what are given to consultants for project analysis instead of the raw numbers. Many systems across the country massage the raw ridership numbers by at least 15% or more through tricks like rounding up to the next 1,000, double counting certain fare categories and "assuming" the raw data is missing some numbers if they look to low.
Then one must look at who commissioned the rail study and holds a vested interest in the projected ridership numbers being good. The City of Hawaii.
Bottom line to all of this. Projected ridership numbers are just that, projected. A mathematical formula generates what amounts to a wild guess. Just about all of the projected ridership numbers for numerous transit projects built across the US have been wildly off base and always on the high side. Chop that projected ridership number in half and perhaps you'll have a closer and more accurate wild guess as to what the future ridership will be.