Tuesday, January 30, 2007

If You Build It, They WON'T Come?

Whatever one's opinions about Caltrans' plans for Highway 50, nearly everyone agrees that the so-called "carpool lane" is about expanding capacity so that the freeway can carry more cars. Pete Hathaway says so. Caltrans also says so in the project description.

It boggles the mind, then, that the planners and engineers at our state's largest transportation agency think that they can expand the capacity of a freeway by 20% to 25% without any effect on the volume of traffic! However strange it sounds, it's true. Below is an excerpt from an email from Caltrans in response to a question asking for justification of their claims that widening Highway 50 will not increase the total number of Vehicle Miles Traveled, and furthermore will not increase the total number of Diesel Vehicle Miles Traveled:

This project will not increase average daily VMT, but rather it will help to maintain mobility in the face of such growth.

The bus/carpool lanes are not built to facilitate diesel truck traffic or accommodate more diesel trucks to use the carpool lanes. The percentages of heavy trucks were not assumed to change in the future build models. The bus/carpool lane was not assumed to have any effect on heavy trucks, as they are not allowed to use the bus/carpool lane, even if they have the required number of occupants.

The only percentages that did increase over time were for bus/carpool vehicles (buses, vanpools, 2+, 3+ autos). There was a corresponding decrease in single-occupant vehicles. Buses can be either diesel powered or other (e.g. gasoline-hybrid, CNG). It's likely that non-diesel powered commuter buses would increase over time. Small delivery trucks were not considered as HOV vehicles.

In other words, Caltrans thinks that you can add an extra (HOV) lane to a congested freeway without affecting any increase in the total volume of traffic on the freeway! Furthermore, Caltrans thinks that no trucks or diesel vehicles will be added to the freeway, even though the project creates more space for them in all lanes. "Increased capacity" apparently doesn't mean "increased volume" to Caltrans planners.

What a relief to know that our state's engineers have mastered the magical thinking skills that allow us to continue to build freeways free from negative impacts of the increased traffic that they are built to accomodate!

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