A winter’s worth of shoreline erosion has prompted the closure of one of the Great Highway’s two southbound lanes south of Sloat Boulevard, according to the San Francisco Department of Public Works.

Crews from the department spent the past four days installing concrete barriers to keep drivers, bicyclers and pedestrians off the outer edge of a 650-foot stretch of the coastside thoroughfare, according to DPW spokeswoman Christine Falvey. The season’s storm activity has eroded the shoreline right up to the guardrail in that area, north of Fort Funston.

Erosion has been an ongoing problem along the coastal bluff since 1999’s El Nino storms buffeted the area, Falvey said. In 2003 the city built a side road with an eye toward future erosion problems on the main road. The department is monitoring traffic in the area to see whether that road is needed, she said.

The realignment is a safety measure as crews from the city, the National Park Service and the Army Corps of Engineers determine a long-term solution, according to Falvey. While the city is responsible for the roadway, the coastline itself is managed by the Golden Gate National Recreation Area.

Meanwhile, crews will be replenishing the sand and soil that the ocean has reclaimed.

That way the waves will chew away at the sand instead of the coastline, according to Falvey.

Erosion is an expected part of the seasonal cycle, Falvey said.

Public works crews spend much of the summer replacing sand where necessary. This replacement sand comes from the San Francisco Ship Channel, and further north on Ocean Beach, where sand tends to blow onto the roadway.

“We move a lot of sand from there and since we need it, we just move it south,” Falvey said.

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