Regional registry
Louisiana
2 documented locations. Others may exist; funding to check ran out.
Des Allemands Crossing Verge Angle Demonstrator
Reported from the edge of Des Allemands Crossing, beside a parish-maintained service road and a drainage canal, the Parish Verge Angle Demonstrator is a concrete-and-aluminum display intended to show the recommended mowing angle for roadside verges. The installation appears to be maintained by the St. Brice Parish Roadside Appearance and Drainage Coordination Committee, whose small signboard still lists a 1997 hotline for reporting "slope irregularities." The object consists of three adjacent embankment sections cut to different grades, each labeled with enamel plates indicating runoff behavior, mower access, and ditch visibility. One panel has been replaced in a mismatched green, suggesting either storm damage or a procurement issue that would likely reward fuller documentation.
Our Lady of the Interchange
A fieldstone Marian grotto standing on its original 0.7-acre parcel, which since 1971 has been entirely enclosed by the northeast loop of a highway cloverleaf. It is reached by a marked maintenance drive, and Mass is said at the grotto twice a year under Department of Transportation and Development escort.