Economist questions KABATA traffic projections

MAT-SU — An Anchorage economist says he thinks that Knik Arm Bridge planners are off in their estimates of how many people are going to want to drive the span.

“I think they’re overly optimistic and I think that way because of the work that we’ve done here projecting future population growth,” said Scott Goldsmith, a University of Alaska economics professor and director of the university’s Institute for Social and Economic Research. “I guess I’m just concerned that the work that we’ve done might be mischaracterized or misused.”

The Knik Arm Bridge And Toll Authority’s chairman, Michael Foster, said that while planners used ISER’s numbers, they actually improved on them. He said the numbers are based largely on population growth. ISER put its study together in 2009 before the U.S. Census came out in 2010.

“The actual census in 2010 is 11 percent higher than the ISER numbers,” Foster said. “Our Wilbur Smith population projections actually uses the ISER 2009 numbers but then we correct and we benchmark against the 2010 census numbers.”

So what are those numbers?

According to KABATA’s report, drafted by out-of-state consultants Wilbur Smith Associates, which does a lot of work in traffic projections, at $5 per trip, the bridge can expect to see 36,000 trips per day by 2035. ISER estimated 17,700 trips per day.

Which seems like a pretty big difference.

Those numbers, though, are based on population growth. Foster said that from that perspective he thinks the two studies aren’t so far apart.

“ISER projects that in 2035 that the population of the (Mat-Su) borough will be 170,000. Our model projects that in the year 2035 it will be 192,000,” Foster said, but noted that the ISER study’s estimate for 2010 borough population was 11 percent off. “I believe if they went back and did the ISER numbers using the 2010 numbers they’d be dead on our numbers.”

Goldsmith raised another question, saying that the Wilbur Smith numbers show not just an increase in population but an increase in the percentage of those people who will be using the bridge.

“People would be making more trips from Anchorage to Fairbanks and vice versa on a per-capita basis than they are today,” Goldsmith said.

Both agreed that the bulk of bridge traffic will originate in either Anchorage or the Valley.

The growth in the Valley, Foster said, is going to be clustered around its landing. It’s a trend the Valley has seen for sometime — the biggest booming population center in the Valley is along Knik-Goose Bay Road. And it’s that area that would see a savings in commute times if a bridge is built across Cook Inlet in the Point MacKenzie area.

“Only somebody who is stupid would drive to Knik to cross the bridge to go to Palmer and the people of Mat-Su are not stupid,” Foster said.

Foster said that critics of the bridge project tend to want to have it both ways. He gets criticized on the one hand by people who think he’s too optimistic about traffic projections and criticized on the other hand for dumping too much traffic into Anchorage.

“You can’t have it both ways,” he said.

But Goldsmith said that if he’s right that KABATA is overly optimistic, building the bridge might be a mistake.

“If the bridge is built and trips don’t materialize and the toll revenues are not as high as projected then the question is who pays for the shortfall? How big could the shortfall be and then who pays for that shortfall?” Goldsmith said.

It’s a question that’s lately been on lawmakers’ minds. The state Legislature is set when it resumes to decide whether to agree to cover those shortfalls. KABATA fully expects to shortfalls in the first few years of the bridge’s operation but projects excess revenue in the later years.

And speaking of the future, Foster asked what the state is going to do if the borough’s population doubles. The Glenn Highway is at capacity now. Doubling its capacity would cost approximately $370 million. Building a bypass around Wasilla? That’s another $350 million.

“If you don’t build a bridge you have to do those improvements and guess what? That’s all state and federal money,” Foster said.

Contact Andrew Wellner at andrew.wellner@frontiersman.com or 352-2270.