A spokesman for the Texas Department of Transportation, said instead of an underpass at Highway 151 and Loop 1604, an overpass will be built to protect the habitat of a federally protected, endangered spider.
"To avoid digging that much and less excavation, we're going to run 151 over 1604 right there into Alamo Ranch Parkway," said Josh Donat, TxDOT spokesman.
However, in doing so, Donat said the cost is now $44 million, nearly triple the price tag of $15 million, funds that now will help pay for the overpass.
Donat said the plan had been in reserve when the project for an underpass was halted by the discovery of the Bracken bat cave meshweaver, a tiny, translucent, blind spider that lives in karsts or caves.
"Increasing urbanization and population growth are the primary threats to the meshweaver and its habitat," said Lesli Gray, U.S. Fish and Wildlife Service spokeswoman.
She said that was why the spider was put on the endangered species list in 2000 due to the destruction and degradation of its caves.
Gray said the efforts to help in the recovery of the rare species also assist in maintaining healthy and functioning karst ecosystem which are unique in Central Texas.
Gray said this time, the project likely will not be halted, even if other karsts are found.
Donat said although TxDOT has a plan and conditions approved by USFWS, "The likelihood of encountering a new or unknown feature is extremely remote, given the diminished amount of excavation in this project plan."
He also said TxDOT already has tried to document the caves that are known in the area, and it has protocol in place if they find more karsts or meshweavers.
Donat said work is scheduled to begin next year, with completion expected at the end of 2017.