The Spider and
the Overpass
When would a highway engineer ever need to know what Cicurina Venii is?
When the endangered spider species causes a massive construction halt.
The connection with biology, endangered species, and transportation may not always be one that you make instinctively, but in 2012 all three came into alliance in a most convincing way.

In April of 2012 work began at the intersection of Highway 151 and Loop 1604 in San Antonio, TX. However in late August, after a rain downpour, workers noticed an underground cave that was home to some very rare inhabitants. The 6-foot deep spider hole was the home of a Braken Bat Cave meshweaver (Cicurina venii), an eyeless arachnid named for the unique web it spins. The meshweaver, which was first discovered in 1980, has been on the endangered species list since 2000, and its unearthing immobilized the highway construction project.

The $15 million development was stopped until the U.S. Fish and Wildlife Service and Federal Highway Administration could come to an agreement on how not to disturb the endangered spider's habitat, but still keep traffic moving for the 80,000 commuters who would use the corridor.

In 2014, an agreement was reached much to the enjoyment of drivers, scientist and transportation officials, but at a much higher bottom-line. The project was redesigned; originally slated to be an underpass, the intersection was converted to an overpass that will connect 1604 to 151. Unfortunately, the revamped project would cost $44 million, almost three times the original cost. Although this is a much higher cost, overpasses require less excavation, decreasing the likelihood that workers will damage the cave habitats where the endangered spider might live.


CBS Houston. (2012). Endangered Eyeless Spider Indefinitely Delays $15M Texas Highway Project. Retrieved from

Serna, Stephanie. (2012) Rare spider stops construction on State Highway 151 and Loop 1604

TxDOT: Braken Bat Cave meshweaver found by median. Retrieved from
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This material is based upon work supported by the U.S. Department of Transportation under Cooperative Agreement No. DTFH6114H00004. Any opinions, findings, and conclusions or recommendations expressed in this publication are those of the Author(s) and do not necessarily reflect the view of the U.S. Department of Transportation.
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