As you may know, I advocate not just against additional highway expansion and capacity, but actually...less. In part 1 of this series I explored the question invariably asked first by people when I start talking about removing intracity freeways: "but where will the traffic go?"
It doesn't all go to one place, but four places:
1. Regional - Traffic that is going long distances probably shouldn't even be running through the middle of the city if they're not specifically going to a "micro-destination" within that city, particular long-haul, freight trucking, which is the biggest polluter there is. A city, by definition is a place where lots of people are doing lots of different things, interacting and exchanging. Move the pollution away from the people when possible.
2. Local - If people are going to said "micro-destinations" like their job, or a restaurant, or their home, they can and should be using city streets. Investors look at traffic counts and currently much of East Dallas is actually under-trafficked. Hence, much of the property is also derelict. Peak and Haskell couplet for example carry only 7-10,000 cars per day when they're constructed to carry 30,000.
3. Modal Shift - About 25% disappears. It doesn't simply shift to other roads, but other modes. The economy doesn't shut down. We still have our wants and needs. Instead of cars, we realize it makes more sense to move by foot, train, bike, carpool, or shop online rather than in the mall.
4. Proximity - By removing freeways and opening land for development, we restore the value and amenity of proximity. People can live closer to places they work, shop, etc. They can walk. They can bike. The density and tax base affords investment in mass transit. It's proven far more successful to build density via demand then in turn, provide mass transit rather than building mass transit hoping it will yield density.
As for the idea to tear out IH-345 specifically, that road carries 80K cars per day in each direction. That's 160,000 cars in total. Let's break that down in the four directions, 40-40-40-40.
As point 3 suggests, 25% or 40,000 cars will disappear from roads as people start riding DART, telecommute, etc. etc. That's one quartile taken care of. Now we have to address the other 120,000:
4. Proximity - We're suggesting 25,000 people would populate the redevelopment of the IH-345 corridor. If those 25,000 each make two trips per day, that's 50,000 trips that don't need the existing highway segment, because the majority of their destinations within a complete neighborhood are within 10-minute walking distance. So we're up net +10,000, having spoken for 90,000 of the 160K. We have 70K left.
2. Local Roads/Boulevards - Much of the traffic will filter to local streets, driving up opportunities, land value, and commercial activity on moribund streets like Peak and Haskell. As I wrote, they both could handle another 20,000 vehicles. 20+20 = another 40 spoken for. We have 30,000 left.
1. Regional traffic. We have Loop 12, 635, and 190 circumnavigating the city to some degree. Can they handle another 10,000 each? 12 and 635 would have a more difficult time, but 190 is brand new. Sections complete enough for available traffic counts have it moving 50K per day. Well under the 200K per day that 635 moves. It could certainly handle 30,000 extra vehicles per day. Add that to whatever happens with Project Pegasus and the Trinity Toll Road (projected 100,000 cars).
To the earlier point that we're replacing costly infrastructure with little to no tax base around it with exponentially increased population and tax base and far less infrastructural burden, opens up the opportunity to make other infrastructural networks viable, such as bike lanes and streetcars. The increased variety and choice within the network as well as the diffusion of traffic to the four points above, would actually make the city more mobile and efficient by taking out a section of highway.