forecasting

Metropolitan Washington Airports Authority (MWAA) management of the Dulles Toll Road is coming into serious question following a board decision last Wednesday to pay a $325m premium to underground a rail station rather than build it elevated. Nearly 60% or $3.7b of the cost of the $6 billion+ rail project is supposed to be supported with toll revenue bonds on the Dulles Toll Road.

Expectations about traffic forecasts for 20 years ahead as opposed to five years are much lower, with some disregarding entirely 20 year forecasts, especially for new roads. That's a finding of a survey of accuracy expectations by Robert Bain that got responses from some high level transportation officials. At 20 years respondents expect average traffic forecasting error (adding positive and negative error) of 45% compared to about 25% at 5 years.