Keith Browning normally might worry if his math calculations don’t add up.

But when his $2.7 million prediction for rebuilding a stretch of the Farmers’ Turnpike missed the mark by $1.1 million, the public works director for Douglas County couldn’t hide his glee.

Turns out all five contractors willing to do the work ended up discarding Browning’s expertise, instead offering to tackle the job for less.

“We got very good bids — extremely good bids,” said Browning, who also serves as county engineer.

Perry-based N.R. Hamm Construction emerged as the lowest of the low bidders Wednesday for the project to rebuild a damaged and relatively dangerous stretch of road: 2.26 miles between County Road 1029 and the northern end of the South Lawrence Trafficway.

The project calls for widening the road to have two 12-foot-wide lanes, plus paved shoulders and, alongside, flatter roadside slopes to improve safety. Drivers also will be able to see farther ahead of them, as hills will be flattened and dips will get filled.

Hamm’s offer to do the work for $1.6 million — the lowest of five bids opened Wednesday — quickly won approval Wednesday night from Douglas County commissioners.

Browning’s own “engineer’s estimate” had pegged the constriction cost at $2.7 million, on a project with a total budget already set aside of $3 million.

“If you’re going to be off,” Commissioner Jim Flory said, “I’m glad you’re off in this direction.”

Browning acknowledged that the difficult economic climate led to the favorable bids, with contractors hungry for one of the few such construction jobs available in the area.

Construction is expected to start in June, and the road will be closed between the trafficway and the beginning of the curve of County Road 1029. A marked detour will add four miles to the trip for drivers by directing them onto the trafficway, U.S. Highway 40 and a southern stretch of 1029.

Construction is to be substantially complete — that is, with the Farmers’ Turnpike back open to unrestricted traffic — by Thanksgiving, Browning said.