On the books, there is only one way by car off Long Beach Island: Eighth Street, also known as Route 72 West, in Ship Bottom. This summer, however, motorists increasingly seem to be taking different ways to get there, due, in part, to traffic redesigns in the N.J. Department of Transportation’s multi-year Causeway project.

“It’s become a highway off the Island,” Mayor William Huelsenbeck said of Fifth, Sixth and Seventh streets where the residential roads intersect with Central Avenue west of…