TxDOT has put out a notice of public meeting for the US75 corridor (not 345 - but everything north): http://www.txdot.gov/inside-txdot/media-room/news/dallas/038-2013.html
There are a few incredibly misleading statistics they cite which seem to serve little purpose but to incite fear and acceptance. The first is that "if left untreated traffic will rise to 420,000." That would make US75 the busiest freeway in the entire country. Busier than the 405 in LA which, by the way, has been shut down for entire weekends at a time during "Carmageddon" without crippling congestion or the literal end of the world. Nor LA.
Furthermore, since no highways in the country actually move that many cars per day, you can reasonably assume that there is a carrying or tolerance capacity at which point traffic becomes too intolerable and drivers go a different route, carpool, take transit, and over the long-term the real estate market shifts to favoring proximity. Business move closer to residential, residential moves away from the busy highway. In other words, there is very little probability it will ever get that congested.
Lastly, as for that congestion, to wit TxDOT says congestion on US75 costs drivers $80,000,000 per year. That sounds like a big number. Until you dig into it. When you take those 230,000 cars per day over the course of the year that congestion equals 95 cents per day (less than most tolls) or $347 per year.
This is called the cost of commerce. Now compare that to the cost of car dependence which equals $6,800 per year per capita, specifically due to the highways that fragment and divide our communities, neighborhoods, and businesses coercing us into our cars. We lack real choice as evidence by our 95% car commuting statistic surpassed only by Detroit amongst major US metros.
Based on Victoria Transportation Policy Institute, Texas Transportation Institute, and USDOT/census data, congestion costs the US just under $400 per year per capita for all roads. In other words, that's 1/2 of a DART local yearly pass or 1/4th of a DART regional yearly pass. It is insignificant and uniform throughout the world. Congestion can't be defeated, only worsened. That TxDOT's work is putting all of us into cars, thus congesting the roads, thus guaranteeing the need for them to widen the road. Wash, rinse, and repeat.
Also, keep in mind TxDOT is asking for an additional $2billion per year over their existing $2billion/year budget despite about $18billion in debt.
The problem is demand-sided.