McBlogger is a boisterous critic of tolls. No surprise, then, that he doesn't buy my arguments for congestion pricing I-35 and MoPac. He's written a pretty long critique -- and raised an objection I've never addressed -- so I need to respond.
His main objection is that congestion pricing will screw up traffic on alternate surface streets:
What I'd like to see discussed is the overall impact of congestion on people and on the infrastructure that isn't tolled, like surface roads. We already see a large spike in traffic on Balcones, Expo, Lamar, etc. because congestion is so bad on Mopac and 35. What will happen when we start congestion pricing on certain lanes of these roads? How much of the traffic going to be in the neighborhoods?
And:
[C]ongestion pricing will eliminate congestion but not traffic which will find alternate routes. . . . [Y]ou're not eliminating traffic, you're merely inconveniencing drivers by making them wait until the pricing declines or by forcing them to an alternate route. But it's not magic, traffic doesn't just disappear.
Congestion pricing is supposed to inconveniences drivers who are not willing to pay the toll. There’s nothing unfair about that because they are inconveniencing every other driver. Each driver who pulls onto I-35 or MoPac during rush hour slows down dozens or hundreds of drivers behind him. It’s just a few-second delay for each trailing driver, but that small delay is inflicted on lots of drivers. It adds up. Congestion pricing makes drivers account for the costs they impose on others.
Most drivers won’t eliminate trips merely because of a little inconvenience. But congestion pricing is about encouraging shifts: shifts from peak travel times to off-peak travel times; shifts from congested roads to less-congested roads; shifts from cars to buses. So when McBlogger complains that we’re merely making drivers wait until the price declines or forcing them to alternate routes, my response is, “Yeah. Exactly.”
Look, a lot of these are discretionary trips. We don’t want soccer mom popping on to I-35 at rush hour for a trip to the grocery store if she can go mid-afternoon instead. Or if she can take surface streets. Soccer mom, and all the other discretionary drivers, need to pick a different time or route. (And if soccer mom is rushing to pick up the kids from daycare, she'll appreciate the toll.)
How bad would pricing I-35 or MoPac make things on South Lamar or Balcones or North Lamar? McBlogger and I could argue about this endlessly if we wanted to, but the truth is neither of us really knows. The surface streets would carry more traffic. It would take the traffic engineers with sophisticated models and lots of data to tell us how much more.
But a congestion toll is not supposed to run half the drivers off the road. If it does, it’s too high. A congestion charge is supposed to be just high enough to get free flow. Diverting just 5% of the drivers — to another route, another time or a bus — might do the trick. (Paradoxically, congestion pricing actually increases the capacity of hypercongested roads.)
But let’s suppose that pricing I-35 and MoPac did generate a lot more congestion on Lamar or Burnet. So what? We should do whatever makes most drivers better off. Surface streets carry just a small fraction of the traffic carried by I-35 or MoPac. Fewer people suffer when these streets are congested than when MoPac and I-35 are congested. Trading a congested MoPac for a congested South Lamar is not the ideal trade, but it's better than not making the trade at all.
A couple of final points. McBlogger suggests that SH 130 will be a "test" once the southern leg of 45 opens to connect it to I-35. It won’t be. I-35 is free. SH 130 costs money, and it’s longer to boot. SH 130 won’t be a fair test until we price I-35 and make SH 130 free. (I’ve been arguing we’re pricing the wrong road for more than two years, by the way.)
Finally, McBlogger argues that we’ve got lots of bad road design that clogs traffic (for example, forcing southbound 183 drivers to merge into one lane to get onto MoPac). This is true. Bad designs need to be fixed. But they won’t solve the problem. Merely increasing capacity won’t solve the problem, either. I've been reading McBlogger write about tolls for a while, but I’ve yet to see him address induced demand. There are already people delaying their trips or taking alternate routes or modes of transportation because of congestion. Improving capacity might clear congestion for a little while, but the faster travel times will draw more drivers until congestion is as bad as before. The only permanent solution is to price the roads.
We both recognize, I think, that fixing Austin’s traffic problems is crucial for its growth. But I don’t believe that tinkering with road design or capacity can make much difference in the long run.
Update: McBlogger's reply.
