By 2012, corn dogs and cotton candy could be year-round fare at Fair Park.

Officials at the State Fair of Texas said Monday they want to convert the midway into an amusement park to compete with Six Flags Over Texas, though on a smaller scale and with a cheaper price.

A roller coaster is planned, as is a ride called the Top of Texas Centennial Tower that will send thrill-seekers 500 feet into the air.

The 20-acre midway would be transformed into a good-weather playground, with enormous flowerbeds covering acres of pavement, inflatable buildings and water features all around.

A high-speed boat adventure ride tentatively is pegged to open in 2013, a year after doors open to what will be called Summer Place Park. Admission would be $30, compared with the $49.99 full price for Six Flags.

But to pay for the expansion, estimated to cost more than $20 million, the State Fair of Texas will need to spin off some serious cash in the next several years.

"We have to earn it and put it in the bank, so we've been saving up for this," said Errol McKoy, president of the State Fair of Texas, an independent agency that operates the annual extravaganza, the nation's largest state fair. "But over the next two or three years, we'll have to have some pretty good fairs in order to afford this."

Still, several million is already in the bank – and a good State Fair this fall, said McKoy, could easily add another $5 million or more. If sales are strong this fall, the $11 million tower will be on order by winter, he said. It takes 18 months to assemble.

During that time, McKoy said the State Fair will use profits from the 2010 and 2011 events to pay for the $8 million as-yet-unnamed roller coaster they've picked out.

"We've found a coaster that does a lot of acrobatics but doesn't take a lot of land space up," McKoy said, adding that it can compete with larger coasters at Six Flags in terms of excitement, but won't match the size or distance of the others.

Last year, the fair sold more than $29.5 million in food and ride coupons, but McKoy would not disclose total expenses. In 2008, about 3 million attended the State Fair.

The Top of Texas Centennial Tower is named for the 1936 Texas centennial, a pivotal event in the history of the State Fair that left as its legacy one of the nation's largest collections of buildings in the art deco style of architecture. It will be the largest tower of its kind ever built, McKoy said.

"The Seattle Space Needle itself is taller, and Reunion Tower is 550 feet, but this will be the highest tower ever manufactured that will serve as a ride," he said. A cabin will take about 150 riders on a swiveling, snaking ride up 500 feet, before returning them to the ground. About 1,000 passengers an hour could ride.

In addition to the big rides, the entire midway will have to be transformed each year to mirror the manicured look that is the hallmark of theme parks, but rarely associated with raucous annual events like a state fair. As many as 150 suites – similar in style, he said, to the corporate suites that will be featured at the HP Byron Nelson Championship – will be available for rent by families, he said. The $30 cost for tickets will also provide a pass for at least one other venue at Fair Park, which include an IMAX theater, the Hall of State and other historic structures.

Besides the rides, the capital investments needed for the expansion will cost about $5 million, and would be complete by 2012–if all goes well with the sales between now and then.

"The planning has been finished, all of our financial analysis has been done, and our feasibility study has been done," McKoy said of the park.

There's plenty of optimism but any bet on big sales numbers these days faces long odds, given the down economy. The theme park industry has been especially hard-hit.

But McKoy and others excited about the plans said the State Fair this year may have a trump card – the opening of the $1.8 billion DART Green Line, its art deco-inspired Fair Park station just steps from the park's front gate.

Officials gathered there Monday, celebrating its on-schedule construction. DART opens four stations Sept. 14, and will open another 16 as the full 28-mile Green Line begins service by December 2010.

"It is absolutely huge," said Craig Holcomb, president of Friends of Fair Park. "It takes you to the front gate of Fair Park, and with no need to walk a block or anything – it puts you right there. That is going to cause people to use it."

Betty Artis, marketing manager for the Fair Park division of the city of Dallas parks and recreation department, said the arrival of the Green Line has pumped up the network of museums, arts venues and other sites – home to some 1,200 events each year – that call Fair Park home.

"It's going to be convenient for people who don't want to go through the trouble of driving their cars and finding a place to park," she said. "They're just going to go to the park and ride, get on the train and go to downtown Dallas or Fair Park."

McKoy said competing against Six Flags Over Texas won't be easy, but he believes a cheaper, quicker amusement-park option will resonate with cost-conscious families.

"At the end of the day, people will enjoy riding out on the light rail, and enjoy an economical visit," he said. "And we'll have a lot of good food."