MARIETTA — Special purpose local option sales tax collections are more than $8 million higher than projected since collections began Jan. 1, which is a good sign that the economy is improving, county Chairman Tim Lee said.

“It’s an excellent indicator that things are starting to turn around here in Cobb County,” Lee said.

Still, “it’s a four-year program so we need to take it in stride and not look at reallocating that until we get further into the program,” Lee said.

The 2011 SPLOST was originally projected to collect $465.3 million.

Collections for the first nine months were projected to come in at $88.8 million through September. Instead, they are at $97.5 million.

“It’s an $8.6, almost $8.7 million, difference,” county comptroller Bill Volckmann said.

The county’s finance office used income data from the 2005 SPLOST to estimate projections.

“When we adopted this SPLOST, we were in the middle of the economic downtown,” Volckmann said. “We didn’t want to be overly aggressive with our estimates, so we basically extrapolated the last year and a half of the 2005 SPLOST collections and projected that forward for this new SPLOST.”

The county’s six-year 2005 SPLOST, which collected the 1 percent sales tax from Jan. 1, 2006, through Dec. 31, 2011, was originally projected to collect a total of $825.9 million, but only brought in $761.5 million.

That meant the county could not complete all the projects on the list.

“We built the courthouse and the jail, and those were set budgets. The projects that were forced to be cut were DOT related,” Volckmann said. “Now, on the same note for this new SPLOST, DOT would reap the benefits of having any excess.”

The county will continue to collect the current SPLOST through Dec. 31, 2015, even if it reaches the total projected income of $465 million before then.

“We have projected projects that we need to address that were voter-approved in the event we had more,” Lee said. “The voters approved the SPLOST with the understanding that if we had more revenue than projected that we would address the Tier 2 projects, so we need to continue in that tone.”

The county intends to spend $251 million of the income on transportation upgrades, such as widening Barrett Parkway to six lanes between Old Highway 41 and Burnt Hickory Road. That $21.7 million construction project, which also includes intersection and signal upgrades, is to be completed by next summer.

Twenty-seven percent of the tax revenue is set aside for Cobb’s cities to spend on their own list of projects. The six of them each get a portion based on their population size. The overall projection for this portion is $130 million.

Marietta gets 9.3 percent; Smyrna gets 7.1 percent; Kennesaw gets 4.6 percent; Acworth gets 2.8 percent; Powder Springs gets 2.2 percent; and Austell gets just under 1 percent, Volckmann said.

“They have a set percentage rate instead of a set dollar rate, so if we collect more, their percentage stays the same, but they actually get more as well,” he said.

Parks and recreation projects are to consume $82 million of the SPLOST income; building modernizations are to account for $17 million, and public safety enhancements, $13 million.

Volckmann said as the first year of collections comes to a close, the county’s finance office will likely come up with a revised revenue budget to present commissioners for adoption in February.

Donald Sabbarese, director of the Econometric Center at Kennesaw State University, said the more frequently a forecast is done the more accurate it will be, since it is based on the latest information.

“Let’s assume nothing drastically changes. Then I guess that it’s safe to say that the trend they’re looking at in terms of tax revenue should continue,” Sabbarese said. “The caveat there is that, for instance, we don’t go over the fiscal cliff and go into another recession, which I guess if I was a betting person I would bet that that’s not going to happen, so I would say that the trend in terms of increased revenues probably would continue.”