• Eric Slotboom: Houston Freeways: A Historical and Visual Journey; Slotboom; 2003; 404 pp; illustrated with hundreds of color photos and maps; $29.95 plus shipping ($34.95 in stores, mainly in Houston).

Some people collect books about cars. Some collect books about airplanes. I collect books about trains. Eric Slotboom hopes there are collectors of books about freeways, because he wrote, designed, and paid for the printing of this lavish, hard-bound book about Houston’s freeway network.

Before I read this book, I knew that the Houston urban area, which has about 2.5 million people, has more miles of freeway per capita than any other urban area larger than 1.5 million people. In fact, it has nearly three times as many miles of freeway per million people, and well over twice as many lane miles of freeway, as Los Angeles.

But I didn’t know that, from the beginning of post-war freeway construction, freeways in the Houston area were built to the most advanced designs: wide lanes, wide shoulders on both the inside and outside of the lanes, high-speed junctions, and frontage roads on both sides for local traffic.

Many states and regions use cloverleafs at the junction of two freeways. These often force drivers to slow to as low as 20 mph, which becomes a major source of congestion. Houston freeways were built instead with flyovers stacked four and occasionally five high so that people could go from one road to another without significantly slowing down.

There are plenty of junctions, as Houston’s network includes three major rings (counting a small, inner-city ring) and 14 spokes heading in all directions of the compass. Not all of the spokes reach all the way into the hub, but there are still about 30 major freeway junctions.

Slotboom describes how Houston’s freeways were built in two major waves. The first started in 1948 and ended in the late 1960s when inflation caused highway construction costs to grow nearly four times faster than gasoline taxes and other highway revenues. Like other cities, Houston had an anti-freeway movement that managed to stop a few planned roads, but lack of funding and Houston’s rapid growth were the real problems.

By 1983, the Texas Transportation Institute ranked Houston as the first or second (depending on measure) most-congested urban area in America. The region responded that year by creating the Harris County Tollroads Authority, leading to the second wave of construction of advanced freeways, now including busways and carpool lanes.

At nine inches by 12 inches, Houston Freeways is almost a coffee-table book. Yet it provides fascinating information about both the political history of freeways and the technical details of freeway design. Among the innovative designs illustrated here are:
• Vehicle impact attenuators — the rubber bumpers found covering many concrete barriers, invented by our friends at the Texas Transportation Institute and now saving lives all over the country;
• Wishbones — ramps to get vehicles on and off transitways that are in the center of freeways and otherwise cut off from the outside;
• The Texas-T ramp — an alternative to wishbones;
• The Z-pattern high-mast configuration of nighttime lighting — designed to provide light above and behind drivers so they wouldn’t have to look directly into a floodlight;
• The merits of building roads with 15 inches of concrete instead of just eight.

In its most recent mobility report, the Texas Transportation Institute ranked Houston, the nation’s ninth largest urban area, 48th out of the 50 largest urban areas in America. This isn’t so much because Houston’s congestion has lessened over the past two decades as that congestion everywhere else has worsened. By the institute’s measure, Houston’s congestion is 9 percent worse than 20 years ago, while Los Angeles’ is 41 percent worse.

Slotboom isn’t uncritical of Houston’s freeway designers. He notes that the region would have been better off with a grid pattern instead of the hub-and-spoke system that leads to congestion at the hub because it forces many people to drive through downtown even if their destination is somewhere else. He points to embarrassing failures, such as a bridge that was built too low across the Houston Ship Canal, leading to many collisions with ships.

I probably won’t keep this book on my coffee table, but I certainly will keep it as a reference for what other growing regions should (and sometimes shouldn’t) do to ensure mobility for their residents. I encourage you to go to http://houstonfreeways.com/ to review sample pages of the book and consider ordering it.