Sounds like the bridge has been replaced but there is no access through the forestry yet:
"Due to tree felling work there is no access up the forest road from the new Bailey bridge or from the hills down the forest road to the Falls of Orchy car park. Access to the Caledonian Pinewoods in the upper forest will be available via a diversion through Bridge of Orchy." From
https://scotland.forestry.gov.uk/visit/glen-orchy