A swathe of trees and scrub in Swansea East was removed due to repeated trespass and fly-tipping, the landowner has said.
Freight train operator DB Cargo cleared a narrow strip nearly 1km long above the northern edge of Fabian Way, Port Tennant, and erected a new fence.
Bisecting this stretch is a rail line running from Burrows Yard depot to Swansea docks.
DB Cargo's head of safety Marc Binney said there had been eight trespass incidents over the past year on its land. Manhole covers had been stolen, he said, and rubbish dumped.
"In conjunction with Network Rail and British Transport Police we tried other options to secure the site and prevent the trespass," said Mr Binney.
"This included fencing within the site. This was unfortunately damaged by the trespass events and off-road bikes.
"This left us with no option other than to completely secure the area to prevent trespass and ultimately any injury."
Mr Binney said DB Cargo asked Swansea Council if the fencing could be put up just outside the site's perimeter, along the border of Fabian Way itself, which would have enclosed the trees. But he said the request was turned down.
The felling and scrub clearance took place before the bird nesting season.
DB Cargo operates trains at Burrows Yard and also accepts freight from other operators.
St Thomas councillor Clive Lloyd said it was sad when trees which weren't diseased had to come down, but he had sympathy with any landowner who had to deal with fly-tipping.
Cllr Lloyd said fly-tipping was a real problem at the Tennant Canal, which runs just to north of Fabian Way.
"It's disgusting, it's disgraceful, I wish people would not do it," he said.
