Fortworthology has a post up about widening roads to decrease congestion:
Road widenings are almost always done in the name of “reducing congestion,” but in fact they have the opposite effect: widening roads increases traffic. The old saying goes “widening roads to control traffic is like loosening your belt to control your weight,” and it’s pretty accurate.
Traffic will swell to fill capacity. It’s a phenomenon called “induced demand.” Build more lanes, and you alert drivers that there is now more capacity on the road. They will use that capacity. Because the road now “flows better,” people will take advantage of that capacity. This, in turn, creates more congestion, bringing us back to the starting point. How many years after 377 is widened from four to six lanes will it be that TxDOT comes up with a plan to widen it from six to eight? There will never be enough lanes for the highway crowd. Benbrook must make a choice – would it rather have four lanes of congestion, or six lanes of congestion? There will be congestion, sooner or later, in either design – the six lane configuration will just have that many more cars in gridlock. In addition, the wider road will increase congestion on surrounding local streets feeding into it.
If you are a local elected official, take the time and read the whole thing.