Further, technological advances are expected to substantially increase the capacity of urban freeways. There is sufficient space to expand Interstate 35 throughout most of the proposed route, and additional traffic relief will be provided by the proposed State Highway 130. Considerable progress has been made in improving air quality in the United States and is directly attributable to improved vehicle emission technology. On the other hand, virtually none of the air pollution improvement in the U.S. is attributable to transit, much less urban rail systems such as commuter rail. Because urban rail does not materially reduce automobile use, it cannot materially reduce air pollution.
Rail systems are an exceedingly expensive strategy for reducing air pollution.