No sooner had Iowans approved a 10 cent per gallon gasoline tax increase for infrastructure repair than the Iowa Department of Transportation began looking seriously at widening Interstate 380 between Iowa City and Cedar Rapids. A recent Cedar Rapids Gazette interview with Iowa DOT transportation planner Cathy Cutler reported the agency is designing a six-lane section between Iowa City and North Liberty, and is studying the possibility of adding two or even four lanes all the way to Cedar Rapids.
There are several rationales for additional highway construction between the two cities that bookend what has been branded the I-380 Corridor.
Growing Population and Changing Demographics
Increasing population, and increasing incidence of dual-career couples with jobs in different towns, means there is more traffic between them on the average workday. All must be accommodated on I-380, which is the predominant route between Cedar Rapids and Iowa City. There's a two-lane road, S.R. 965, that once was a viable alternative but has now gone all stroad-y in North Liberty. Bus or train service is non-existent.
The Gazette article, quoting my former Coe colleague Randy Roeder, focuses on the disruption to traffic caused by numerous crashes, suggesting an extra lane each way would allow commuting to continue while the accident was cleared.
As Cedar Rapids, Iowa City and the towns between them chart their common destiny, facilitating traffic along the "corridor" would help to tie the region together.
Transit Perceived as Too Expensive
Those advocating for adding capacity to I-380 assume that any form of public transportation would not be attractive to enough people to be viable.
The DOT and the construction companies are ready to go. But say we're convinced, either by the above rationales or their eagerness, and the additional capacity along I-380 is built (Never mind the dislocation caused by construction while it's happening, or that non-commuters are subsidizing the construction for the convenience of commuters).
What outcomes can we expect? There's been a lot of research on this question, ably summarized by Tom Vanderbilt in his masterwork Traffic, particularly in chapter 6, "Why More Roads Lead to More Traffic (and What to Do About It)."
1. Traffic along the highway will increase. Induced demand is a widely-acknowledged phenomenon, except maybe not by the highway lobby: When more lane-miles of roads are built, more miles are driven, even more so than might be expected by "natural" increases in demand, like population growth. In other words, the new lanes may immediately bring relief to those who wanted to use the highway before, but they will also encourage those same people to use the highway more--they may make those "rational locators" move farther out, for example--and they will bring new drivers onto the highway, because they suddenly find it a better deal. (p. 155)
2. Government budgets will be additionally stressed (p. 161). Remember that the rationale for the gasoline tax increase was we are having trouble keeping the infrastructure we have in repair. Iowa's budget is not exempt from the stress governments around the country are feeling. Our governor recently item-vetoed a bipartisan increase in the education budget, is trying to get private insurers to take on Medicaid clients, and just suggested water quality problems caused by farm runoff could be addressed by shifting funds from educational infrastructure. This is not a fiscal environment that suggests widening highways to achieve optimal rush hour commuting convenience is a really good idea. (See Cortright, "Pulling a FAST One": [The 2015 federal transportation bill] has utterly failed to craft a solution that asks the users and beneficiaries of the transportation system step up and pay for its costs.)
3. People will drive faster, and may take more risks. For years, economists, psychologists, road-safety experts, and others have presented variations on this theory, under banners ranging from "the Peltzman effect" and "risk homeostasis," to "risk compensation" and the "offset hypothesis." What they are all saying, to crudely lump all of them together, is that we change our behavior in response to perceived risk, without even being aware that we are doing so. (p. 181)
4. Hence, there will still be accidents, and resultant rubbernecking. The actual crash, which may or may not close a lane, is only part of the problem, of course. The highway's capacity drops an estimated 12.7 percent because of the line that forms--often on both sides of the highway--to take a look.... The economist Thomas Schelling points out that when each driver slows to look at an accident scene for ten seconds, it does not seem egregious because they have already waited ten minutes. But that ten minutes arose from everyone else's ten seconds. Because no individual suffers from the losses he inflicts on others, everyone is slowed. (p. 163)
The bottom line is that we'd be poorer as state but no happier as individual drivers, and probably would have induced more sprawl towards the outlying parts of the metro areas, with all the attendant negative social, environmental and fiscal consequences. (See Ewing et al. for the latest round of evidence of safety consequences.)
So what can we do? Vanderbilt is big on congestion pricing, to encourage traffic to move from peak to off-peak times. The DOT lists a number of public transportation alternatives worth looking into, mostly involving buses. Given the costs of getting it wrong, both financial and political, I'm for going slow on public transportation. What I'd like to see right now is to get the governments of Linn and Johnson counties to negotiate a no-poaching agreement, tax-sharing and urban growth boundaries. This would allow economic development to occur in ways that aren't wasteful and unproductive, and might lead to the sort of urban density that would make public transportation viable. In any case, as economist Joe Cortright concludes, we should be trying to maximize accessibility instead of mobility.