Another reason I think denser development can help with traffic problems. Traffic is currently bad in this area, right? People are trying to drive through it to get places. Yes, building will increase the number of people, and the number of cars, but it will also increase the number of destinations within the neighborhood so people can make trips on foot, on transit, or by driving, but driving much shorter distances because things they need are nearby instead of 12 miles away. That decreases traffic. Maybe not the number of trips, but the distance driven, and fewer of those  trips will have go out onto highways and major arterials causing traffic jams. 
A well connected street network is also necessary, which I'm not sure if this area has or will have. 

As an example, the neighborhood I live in is one of the denser in the city. Driving through it is very slow. But that is almost never a problem because everywhere I need to go is only a mile or two away.