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Environmental Division

Natural Resources Office, Ecology Section

James K. Polk Building, Suite 900
505 Deaderick Street
Nashville, Tennessee 37243-0334
Phone: 615.253.2472
Fax: 615.741.1098

Dr. Deedee Kathman, Supervisor


From time to time, TDOT may encounter physiographic features, which require special consideration during the project design and construction processes. These include caves, sinkholes, and cedar glades. Where possible, TDOT attempts to avoid these features; however, avoidance is not always possible, in which case TDOT tries to minimize impacts to these features.

Tennessee has more documented caves than any other state, more than 8,400, with the majority being found in the eastern three-quarters of the state. These caves range in size from small openings that may run underground for only a few feet to the longest known cave in Tennessee, which exceed 33 miles in length and is the ninth longest cave in the United States.

Caves can affect roadway construction in several ways. First, roadway stability can be an issue if a project passes over a cave entrance or an associated passage. Second, water quality can be affected if untreated runoff is allowed to enter a cave, not just during project construction, but also after the project is completed. Third, there are a number of species, some listed as state or federally threatened or endangered in Tennessee, that are restricted to cave habitat. As a result, a roadway project may require restrictions with respect to season or proximity to a cave.

Sinkholes are similar to caves in that they occur primarily in the karst areas of Middle and East Tennessee. Although most appear only as large depressions, some may have openings in the bottom and more closely resemble pit-type caves. As with caves, stability and water quality are two of the primary concerns that affect roadway construction.

A lovely cedar glade in the Great State of Tennessee. Cedar glades, which occur predominantly in the Central Basin of Middle Tennessee, consist of areas with shallow soils where bedrock is exposed or close to the surface. Several rare plant species are found in the glades that occur nowhere else in the world. As a result, roadway alignments may be shifted to avoid cedar glades where possible.



Middle Tennessee Cedar Glade