Friday, 09 August, 2002
Traffic is a thorny problem. I've been running across some some rather interesting traffic research in my hunt for some project related data (looking for electronic maps and traffic count data). Mostly I try to skip over the research because I don't really have the time to read it, but the Texas A&M University 2002 Urban Mobility Study caught my eye. If you're at all interested in traffic congestion (and who isn't, if they commute to work), you should take a look. I found the Issues and Measures page particularly interesting. The pages linked from that page do a very good job of explaining the current state of the problem, and identifying many of the factors that cause urban congestion and why it's so difficult to solve. For example, in the discussion of why just adding roads can't solve the problem, there is the answer to the common question "Why don't I see much relief in my travel time [when a road is added or expanded]?" The answer lies in what's called a "triple convergence:" travel moves to the new road from other times, other roads, and other modes. Overall, it's an interesting study, and well worth the read.
If you're looking for road map data, by the way, your best bet is your state's Department of Transportation. In Texas, the DOT gives the data to the Texas Natural Resources Information System (TNRIS), where you can download files, or obtain them via CD (for a charge). The files are in GIS formats like DWG and E00, so you'll need a program like AutoCAD (with the mapping module) or ArcInfo to read and display it. Traffic count information is a bit more difficult to come by because it's not always collected by the state. Many city and county governments collect traffic counts, and there doesn't appear to be a centralized repository, at least not that I've found in Texas.
Geographic Data Technologies (GDT) sells road map and traffic count data, by the way. The nice thing about dealing with them is that you can get everything from a single place. It's expensive, though, if you're looking for data on every state. Expect to pay upwards of $10,000.00 for nationwide road map information.