One of three routes in the Active Schools Travel programme can go ahead while more consultation occurs for the other two routes.
The Sea to Mountains route is set to be completed in April 2022.
The route begins at Blackrock DART station and will run to Slangriver Greenway
Sea to Mountains is one of three routes planned in the Active School Travel project.
The other two routes have been postponed due to controversy over the Deansgrange Road being turned into a one-way system.
Further consultation is underway and a report is due back to councillors in December.
Director of Dun Laoghaire Rathdown County Council Robert Burns spoke at Monday's monthly council meeting to give an update on the Active Schools Travel programme.
He said: "I think it would be fair to say given that as it's an active schools travel project that we are looking to get this completed to have a reasonable amount of time while schools are still in session.
"The Active Schools Travel initiative consisted of three routes initially. So what we have done is separate out this route because it doesn't involve going through Deansgrange.
"Because we have uncertainty on what will happen on the Deansgrange element, it's difficult for us to finalise the scope of the work there and therefore the scope of the application, and that's why there's still a degree of uncertainty in terms of identifying what the costs may be."
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