The amount of traffic using Wales' biggest hospital as a "rat run" and causing gridlock has dropped by 7% after changes were made to the roads.
Hospital bosses made changes last August in a bid to help ambulances reach the emergency unit more quickly at the University Hospital of Wales (UHW) in Cardiff.
Barriers were installed and traffic is not allowed to drive past the unit.
The gridlock also led to people being late for appointments.
Cardiff and Vale University Health Board is now planning to introduce a direct weekday park and ride service for patients, visitors and staff in a further bid to keep traffic off site.
It will start on 2 May and operate from Cardiff East park and ride at Pentwyn from 06:30 to 19:15, running every 20 minutes, which should also free up car parking by 12%.
There are also plans to introduce bus and cycle hubs at UHW.
Geoff Walsh, director of capital, estates and facilities at Cardiff and Vale University Health Board, said: "The traffic management system was implemented to allow clear access for emergency vehicles onto the site which has been successful.
"It has also improved the bus access with Cardiff Bus reinstating two services following the improvement of site accessibility."
He added: "We are still looking at ways to stop people using the site as a thoroughfare."