A highway alignment where multiple designated routes share the same physical pavement for a certain distance. This happens when two distinct highways merge to cross a geographical barrier or bypass a city before splitting again. Traffic engineers must design signage carefully in these sections to prevent driver confusion.
Heard on the job
The concurrency of I-81 and US 11 through that corridor makes exit numbering tricky.
Also heard as
- multiplex
- overlap
Do not mix it up with
- Wrong-way concurrency: A wrong-way concurrency is a specific type of concurrency where the two overlapping routes are signed in opposite compass directions.