What does TR mean on an oversize permit?

Traffic Route. Pennsylvania's traffic routes, its signed state routes: TR 209 is Traffic Route 209 (signed PA 209 or US 209).

On real permits

PrintedMeansState
TR 209 (Traffic Route 209)Signed route 209. PennDOT's permit conditions write signed routes as 'Traffic Route' or 'TR'.Pennsylvania

Decode a whole route line