Shutting down Cardiff Bay Barrage for a fortnight will improve safety for cyclists and pedestrians, a councillor has said.
The 1km stretch of road connecting Penarth to Cardiff Bay will close for two weeks to widen the walk and cycleway by 7m.
Councillor Neil Thomas hoped the scheme will give more room to walkers and cyclists.
But the project has fuelled an online debate over safety concerns on the bridge.
Cardiff Bay Barrage will close later this month for two weeks for improvements.
Cardiff City Council said that the decision to expand the Bay walkway comes in response to feedback to improve the pathway.
They said the improvements will allow visitors easier access to leisure attractions along the Barrage.
The barrage is also the event site for the Volvo Ocean Race in May 2018 for two weeks.
Councillor Neil Thomas, a Labour councillor for St. Augustines, said the improvements will give more space for both cyclists and pedestrians.
However, he said that ultimately people need to be take more responsibility for their actions.
He said more needs to be done to enforce the 5mph speed limit on the bridge, which cyclists are ignoring.
He suggested using wardens to monitor the barrage and to issue on the spot fines.
The decision to close the barrage has provoked online debate about the behaviour of cyclists and pedestrians.
The scheme has sparked a debate online on the Penarth Daily News between cyclists and walkers.
One said: “I have, however, seen many cyclists ignore the 5mph speed limit and bomb along the barrage as if they’re doing a qualifying lap at Monaco.”
And another complained: “It’s so dangerous when people let their dogs wander into the cycle lanes, either off-lead or on the extendable leads. Pretty much happens every time I cycle on the barrage.”
The barrage will close on 27 November until 8 December.