Saint John construction crews unearthed some century-old streetcar rails this week while digging to install sections of the harbour cleanup project.

The tracks were discovered at the intersection of Rothesay and Thorne avenues and have caused some traffic chaos on the busy stretch of road.

The tracks were discovered while digging to install sections of the harbour cleanup project. (CBC)

Rothesay Avenue's eastbound lanes are closed from the Marco Polo Bridge to Reserve Street while the tracks are being removed, which will likely take about a week, said Pierre Leblanc, a civil engineer for Crandall Engineering.

“I'm from Saint John and I had no idea that there was an old trolley car under the road on Rothesay Avenue,” said Leblanc.

Art Clowes, curator of the New Brunswick Railway Museum in Hillsborough, doubts these are the only tracks that were simply paved over.

The People's Street Railway Company started running in 1869 and ended in 1948. (New Brunswick Museum)

“I suspect if you were able to dig up under the whole system, you'd probably find a lot more,” he said.

The People's Street Railway Company started running in 1869, and streetcars stretched up and down Main Street, Douglas Avenue and throughout the city’s south end, said Clowes.

The streetcars stopped running in 1948, he said.

It’s unclear what will happen to the relics. Gulf Operators, the contractors on the job, have been told to dispose of the streetcar tracks as they see fit.