Today's Statesman is full of people whining that "city planners" didn't get Ben White / I-35 right.
For those who still don't get it: NOBODY AT THE CITY OF AUSTIN GETS ONE LICK OF LOUSY INPUT INTO THE DESIGN OF AN INTERCHANGE BETWEEN TWO STATE HIGHWAYS. If the road has a big route number on it (like "2222", "71", "290", "I-35", "US-183"), the city doesn't control the road, and TXDOT doesn't ask for the city's opinion on things.
The sum total of the involvement of the City is to screw with signal timings at intersections with traffic lights, in a few cases. And in most of those cases, the bad design decisions made independently by TXDOT mean that all the signal timing changes in the world won't help.
Today I biked to work. (Well, I biked to the bus to work; I'll be biking all the way home). I forgot to pack my lunch. I had a bunch of leftover change in my bike bag, so I walked along this route to the local McDonald's to get a cheap greasy lunch.
I noticed a pretty long backup, as always, at the Braker intersection. Today, I ended up passing the same stopped cars a couple of times; so I started paying attention. Guess what? I was able to beat a car in the right lane ON FOOT from my office to the other side of the Braker intersection. This wasn't a twenty-foot trek either. According to Yahoo, this is a quarter-mile jaunt.
Why is this intersection so bad? Why is Ben White's rebuild so painful? Two words: frontage roads. When TXDOT 'builds' a freeway, they're actually (9 times out of 10) turning an existing arterial roadway (with driveways, strip malls, etc) into a freeway by using the original roadspace for the new main lanes and then widening into property on the sides to build "frontage roads" (one-way streets which the main lanes exit to and enter from).
So what are the problems with frontage roads?
- They generate their own traffic - cities (who had to give up a ton of land, and in most cases even PAY for the pleasure) aren't going to restrict future development along these streets, especially since TXDOT sells them on the idea that they should keep doing so.
- They cause poor intersection design. Most intersection with frontage roads must operate with four independent cycles - meaning that the people arriving from each of 4 directions are given exclusive use of the intersection on their green light. (The "intersection" in this case extends to both frontage roads). Two major two-way arterials which intersect, on the other hand, operate with two cycles (one for each road) with minor additional cycles for left turns.
- They preclude better interchanges down the road - unless it's to another freeway. In other states, the intersection at Braker would have long since been upgraded with more space, possibly changed to a SPUI (single-point urban interchange which reduces traffic signal cycles to essentially 3), or possibly improved with a ramp modification, or even adding one or two flyovers... but not here. Here, we're stuck the way we are. On Ben White, you can build a direct connector ramp (flyover) since there's another freeway on the other side. On Braker, building a flyover would mean bulldozing everything on one corner of the intersection that located there because of the frontage road.
- They actively exclude cyclists, pedestrians, and transit users. Typically fewer crossings are built or preserved on highways with frontage roads (example: US 183 between Spicewood Springs and 620). This is a minor irritant to motorists but completely screws other users of the roadway, since it's not practical for them to walk a mile down the road, cross at the only remaining crossing for a mile either way (Anderson Mill), and walk back.
What should TXDOT have done in these cases?
Simple: either toughen up and just admit that we can't preserve property access on what's supposed to be a limited-access highway, or do what they do in other states - build perimeter roads (that maintain property access from the city streets, not directly from the highway) rather than frontage roads. This would run counter to the ethos that highway construction and expansion exists to promote retail traffic, which is why it'll never happen in this state, but that's what it would take.