David Hartgen, a University of North Carolina at Charlotte pro-fessor of transportation studies, recently completed a study for the John Locke Foundation on highways and sprawl in the state. He discussed his findings with Carolina Journal in this interview.
CJ: What was the most significant finding in your study?
Hartgen: Well, I think the most significant finding of the study is that there isn’t much relationship between highway construction and urban sprawl and growth, which is population increase outside of urban areas. That’s going on throughout the state. And in fact most of it, most of the tracts in the state in the last decade have no major road improvements, yet almost half of the growth that occurred in the state in the last decade went into tracts that had no major road improvements at all.
CJ: Wouldn’t just the sheer size of the state and comparatively limited number of road projects — wouldn’t that dictate that most of it’s not going to happen in those narrow corridors where the road projects are going on, or the limited surrounding areas?
Hartgen: There were actually over 300 road projects throughout the state and they covered a very substantial share of the tracts in the state, about 500 or so of the 1,500 tracts in the state. I thought when I initiated the study that I would see most of the growth going around urban areas in and around the areas that are now getting road projects. But ,in fact, that wasn’t the case. The growth was everywhere, certainly in suburbs, but also in rural outlying areas and in more distant rural areas, in the mountains, along the seashore and in the rural counties between metro regions.
CJ: What myths does the study debunk?
Hartgen: First of all, that roads cause sprawl. We found that, in fact, sprawl is going everywhere with or without roads. It’s caused primarily by local factors such as sewer and water service, access, schools, crime, sprawling housing and most importantly the underlying health of the local economy.
Another, I think, common myth is that if you don’t build roads that somehow you will stop sprawl. We found that just wasn’t the case. And the analysis suggested that these other factors, primarily the local economic health, was the key underlying determinant. Now what roads do do is they influence sometimes modestly where growth occurs. And they do that by changing the accessibility of parcels and making them more attractive. But what we don’t see when we see growth at these sort of spectacular locations, so to speak, when a new road is opened up we see that the corner is built up as development. What we do not see when we look at those locations is that that growth was diverted from other locations in the region and would have occurred probably somewhere else in the region had it not occurred at that location.
Another common myth we dispelled was the idea that cities are declining internally — that they’re hollowing out and everybody is rushing to the suburbs. We found just the opposite, that all the cities we looked at had rising populations even in the inner parts of those cities.
CJ: Now was that consistent among all the cities or were there fluctuations?
Hartgen: Yes.
CJ: …between Charlotte and Raleigh and Asheville…?
Hartgen: Yeah, the growth rate in the smaller cities was typically less; the more rapidly growing cities had more growth inside. Raleigh, for instance, had a very substantial growth rate. If you look at my density curves for Raleigh you’ll see that it already was at 2,500 to 2,600 people per square mile in the inner rings and rose by perhaps 12 or 13 percent in just one decade. So the myth that people are somehow fleeing from cities, it’s just not true.
The key factor in terms of how much growth occurs is its prior development. When tracts get filled up they’re essentially limited in how much additional growth they can absorb because the zoning caps prohibit additional development. And so if a region is going to grow it has to grow at the edges unless the community is willing to allow increases in density to occur. There are very few communities that are willing to allow that. Planners are essentially creating their own sprawl by setting density caps in urban areas and prohibiting regions from growing freely as they would under market conditions.
CJ: You showed that roads influence where growth occurs. And you’re talking, I guess, within a tract. You say the growth would have occurred in the tract anyway. The roads guide it.
Hartgen: No, not quite. The growth would have occurred within the region anyway. And the roads have some influence in determining exactly where in the region that growth will occur. But the other factors, particularly location of the tract and whether it is appropriately sewered and watered and whether it has quality housing and competitive tax rates and schools, those are the key factors that determine whether growth would occur in a particular tract.
CJ: I know this isn’t always the case, but don’t road projects, to a degree, lead the way in that say a road or an Interstate is continued, like when I-40 went to Wilmington, and as a result things sprouted up? In Johnston County just over the Wake County line, a bunch of retailers cropped up there and that area has exploded. Don’t road projects lead the way as far as motivating local officials to change zoning laws, and causing property values to increase so there’s more of an incentive to sell? Is that true?
Hartgen: Generally it’s not true. In different areas we found that growth followed growth rather than preceded it. Outside urban areas the equation is a little bit different. In suburbs roads can spark a development boom, but that development would have probably come there anyway, albeit at a slower pace. The reason that the spark occurs is that tracts roughly the same distance from the urban center are roughly equal in value. And so by changing the road accessibility to a tract, you are essentially moving it up in the quality rank order of all tracts in the region. And if the change in access is very substantial, for instance a major bridge to an island, a very significant jump in accessibility and in development can occur. So the more spectacular the change in access, the more spectacular the jump.
CJ: A new Interstate exit would be spectacular.
Hartgen: Yes, but only if it’s close enough to the urban region and is otherwise competitive. It has to be sewer-able and water-able and have reasonable taxes and be within a commute zone. Once you get beyond, let’s say, Route 42 in the I-40 corridor, the growth essentially disappears until you get to Wilmington.
I-40 is an interesting case. That road had the effect of directing some growth in the Raleigh area, but it also sling-shotted the accessibility of Wilmington to the monied crowd, shall we say, in the Raleigh region and brought the coast from four hours’ to two hours’ distance. And so the effect of the road there was a little bit different than what you would find in other cases around the state. Wilmington would have grown anyway. It is a very attractive and quality region. But its growth certainly was accelerated by the change in accessibility.
CJ: So if change — say the new exit or the new road is close enough to an urban core — it can bring about behavioral changes among local folks to accelerate development, right?
Hartgen: Sure, but that closeness also means that it would have developed in any case. So what we’re really talking about is the acceleration, and that acceleration turns out to be quite modest relative to the background growth. In most of the cases in the state I found that the road impacts were up between a fifth and a quarter of the underlying growth rate. In terms of the magnitude of what we’re talking about, a mile of urban road widening or rural road widening would, at a maximum, have about the same effect as a small McDonalds restaurant on local traffic — about 1,500 trips a day. Pretty small effects, particularly when you consider that road widenings would typically add 20,000 trips a day in terms of capacity. So the effect of the widening itself is less than 10 percent of the gain you get in the capacity.
CJ: Giving a specific example — looking at the I-540 Bypass in the Triangle; that’s being constructed because of the growth of the Triangle, right — to relieve congestion? But its construction has caused a lot of development to sprout up along 540, right?
Hartgen: Well, I would argue that that development would have occurred anyway because that’s a highly accessible location between the three cities anyhow. And, in fact, the traffic on 540 is quite modest. The current traffic is in the 30,000 range; it’s much lower than the capacity of the road, which is basically a six-lane freeway. So in that case I think that would be an example that falls right in our case line. Yes, there was some growth there and there will be some additional growth there. The road will attract some growth but not much more than would have been attracted anyhow.
CJ: Now the Triangle Town Center (a large new mall), would that have been built anyway without I-540?
Hartgen: Yes, but its specific location is certainly influenced by the improved accessibility of I-540. And so the specific choice of location would certainly have that influence. But the overall effect, I would argue, would have been dispersed throughout the region or there might have been a smaller center developed at that point.
CJ: Let’s take another I-540 example. We’ve got the southern segment on the drawing board south of Raleigh, but who knows when that will happen.
Hartgen: Right.
CJ: So it’s proposed to go through Fuquay-Varina and Willow Spring and a few other small communities. Right now the only major accessibility to those communities is Highway 401. But the degree of congestion that’s on that road is going to limit how much those communities develop unless it’s relieved by another artery, presumably the I-540 southern segment, right?
Hartgen: No, congestion doesn’t really limit growth very much. Most of the traffic in that area is going to be local. It’s true that those communities are tied economically to the Triangle region, but most commuters would be living and working locally; and certainly most non-work trips would be local. So the capacity of 401 and the radial roads into Raleigh is not going to be the determining factor in those communities’ growth.
What will determine their growth is the overall economic health of that region and the attractiveness of those communities. Looking at my charts for the Triangle, I see that those tracts were some of the most rapidly growing tracts in the region anyway, in the last decade. So either somebody is betting on a very long horse, a 15- or 20-year horse — and I don’t know any developers who do that — or else those communities are attractive in their own rights now.
CJ: Is there one particular type of change or addition or any kind of type that spurs growth more than another in road projects?
Hartgen: Well, the most spurring, if you will, would be urban or rural arterial widenings that are right at the edge of the urban fringe. They are within about three or four miles of the edge, either outer edge of the region, or inward. In the case of projects in the urban region they basically allow for expanded growth beyond what is required for congestion relief. And in the case of rural projects, those projects right at the edge of regions, they typically allow for – to spread out so that the commute zone can move about a mile-and-a-half or two miles. And in those cases we found the effects to be about 500 people per decade per mile of investment.
CJ: When we discuss the effect of road projects, shouldn’t the emphasis be more on commercial development rather than population growth, because when you see a new road or an Interstate that comes through, businesses crop up that would otherwise not be there? Would measuring development rather than population be a better gauge of the effect of road projects?
Hartgen: I don’t know if it would be better, but that’s the second half of the study that I would like to do.
CJ: So stay tuned?
Hartgen: Stay tuned.
CJ