Complex sentence: Barrett has been visibly active in pressing for the Cardiff Bay Barrage to be opened up for pedestrian and cycle traffic as the provision would permit many Penarth residents who work in the Bay area to dispense with car travel and reduce traffic congestion on the existing routes.
Split into simpler sentences: Barrett has been active in pressing for the Cardiff Bay Barrage to be opened up for pedestrian and cycle traffic. The provision will permit many Penarth residents who work in the Bay area to dispense with car travel and reduce traffic congestion on the existing routes.