Around 60 tractors and dozens of other vehicles descended on Dublin in a 24-hour protest over beef prices.
The protest began at 14:00 local time, but road closures came into effect on Kildare Street, Molesworth Street, St Stephen's Green and Merrion Square earlier on Wednesday.
Kevin Street traffic is also affected.
More tractors made their way to the Merrion Square area, where some protestors attempted to disrupt traffic.
A similar protest in November also led to part of the capital being closed off for more than 24 hours.
The organisers of the protest - The Individual Farmers of Ireland - said farmers need a better price for their product to help sustain rural Ireland.
The group has also raised concerns over traceability issues in the food chain.
Spokesperson Daniel Long said the demonstration, which is not supported by the main farm organisations, was "significantly larger" than previous protests.
Traffic arrangements - Planned Protest - Dublin City Centre 15th January 2020 pic.twitter.com/TQoHofvjbY— An Garda Síochána (@GardaTraffic) January 15, 2020
He said farmers believe the Beef Task Force, which was set up to deal issues in the beef sector, is a "talking shop".
The tractors converged on Kildare Street on Wednesday afternoon, where the protesters planned to stay overnight.
Gardaí (Irish police) have urged people to use public transport where possible, rather than drive.