The one thing the "higher density" living proponents just can't seem to get past is EXTREME COST of mass transit systems for those philosophies of living. Sure, building a freeway is pretty expensive. But freeways seem like a cheap bargain compared to the prices of light rail and subway systems. Those things are very ridiculous. On top of that, we have a douche-bag class-based society where anyone able to avoid mass transit to make himself look more affluent will do so. And I'm throwing out that one as a voice of experience from living in New York City for 5 years. Plenty of douches there would never soil themselves with riding the subway or a city bus. They had to at least be in a cab or car service if they weren't driving their own vehicles.
At the same time, I have a very difficult time finding sympathy for TX DOT as well as the Collin and Denton County governments for being so dead asleep at the wheel on development of US-380. I have lived in this Red River region for nearly 25 years. As far back as 1993 any idiot could have predicted US-380 was going to need some serious expansion. The very least thing they could have done was the same thing they did with TX-121 between Lewisville and McKinney over 20 years ago: build a wide 4-lane divided expressway with at-grade intersections, but with a huge median. Today TX-121 has a big super highway in the middle of it where that blank median used to be. The same thing should have been done with US-380. And I'll give you another. A bunch of US-82 needs the very same treatment, at the very least between Gainesville and Sherman (if not from Sherman clear over to Paris, TX).
About 10 miles of US-380 between Denton and McKinney could still be converted into a superhighway without much trouble (because there is still room to build). But screw this waiting 5 or more years crap. TX DOT needs to get on the stick pronto and at least grab the ROW from short-sighted developers. It's clear both Denton and McKinney would have to be looped with freeways rather than have them run right through the middle where corridors are too narrow and over-developed.
Inside either city as well as other parts of Collin and Denton counties traffic engineers will have to get more creative about filtering traffic. It's one thing to have a nice, speedy freeway. But a key thing that causes traffic backups that back up onto the freeways is what happens on the surface streets. Better planning has to happen there. Really busy intersections need grade separation or even freeway style interchanges rather than traffic signals. Driveways that spill out onto the main thoroughfares have to be far more tightly controlled and limited. Any major street should have as few driveways and intersections as possible. An optimum 4-lane expressway with at-grade intersections will only have intersections at traffic signals spaced a mile or more apart. Neighborhoods and shopping centers adjacent to the expressway would be more self-contained with fewer entrances and exits. Traffic would filter itself in a more controlled manner. With a well enough designed setup some areas of an urban or suburban center could even avoid the need of building a far more costly freeway if traffic was managed more intelligently.
Some North Dallas neighborhoods and shopping center developments do a decent job of limiting & filtering traffic entrance and exit onto major thoroughfares. Development in many parts of Houston is older and thus not nearly as advanced in terms of traffic engineering. Far more surface streets and driveways are dumping traffic directly out onto main streets and highways in an uncontrolled manner. That leads to those Houston traffic jams that can occur any time of day (or night) and which fuel nightmares. One accident on a surface street near a freeway exit could lead to a snarl that blocks traffic on the freeway itself. I've personally been through that scenario.
The point with all this is freeways alone will not un-snarl traffic in the metroplex. DFW is still very much a car-centric metro and will be for many years to come. That's a call-back to that class argument about who uses mass transit. I wasn't too proud to use the bus, ferries and subway when I lived in NYC but I knew others who wouldn't do that. Douchebags. But that's reality. People love their cars. Street layouts have to be designed better to handle it. Planners need to grow a much stronger backbone and enforce some damned rules on development. Business douches can't just build a driveway entrance wherever they like. The streets and highways have to work like a circulatory system for business. That requires intelligent planning from building high capacity, high speed freeways and toll roads down to surface street networks that work far more efficiently than some stupid, dopey grid where everything craps out directly onto the main drag.