While I agree with population control, I think the problem in the Puget Sound area has more to do with economics than people having too many kids. Eveyone wants to come here to get thier part of a booming economy. The latest info I have read is that developed countrys have leveled off their population growth, it's the third world countrys that are breeding themselfs to death.
One thing I have notice about building new or larger roads to solve traffic problems is that they ruduce the targeted traffic jam for a while, then developers come in and find every square inch of buildable property in the area and make an easy commute a selling point. Within a short time the traffic is back to gridlock and there is another push to build more lanes. On the other hand I don't see people giving up the conveniance of a personal vehicle and using mass transit. I don't know what the answer to this problem is. Maybe more rain and snow.