The Widest Freeway

Near the Sam Houston Tollway the Katy Freeway reaches twenty six lanes across: twelve main lanes, eight lanes of frontage road, and six managed lanes down the middle. It is routinely called the widest freeway on earth, a claim that holds comfortably if the frontage roads are counted and becomes arguable if they are not, and either way it is a startling amount of pavement to cross in the first ten minutes of a drive to Austin. The rebuild that produced it ran twenty three miles, from Loop 610 out to the town of Katy, cost roughly 2.8 billion dollars, and finished in 2008. More than 219,000 vehicles use the corridor on an average day, which is a substantial fraction of everyone leaving Houston in any direction. It has also become one of the most cited real world examples of what transport planners call induced demand. Studies of travel times after the widening found that peak period trips along the corridor were taking longer than they had before the new lanes opened. The explanation is not mysterious: making a trip cheaper in time pulls more people onto the road, and onto it at the hours they would rather travel, until congestion settles back roughly where it started. Engineers had predicted some of this effect. The scale of it here turned the Katy Freeway into a standard case study in traffic textbooks. The right of way follows the old Missouri, Kansas and Texas Railroad line, which is where the town at the far end got its name.