The state's pricing regulator is considering an overhaul of Opal ticketing for public transport for the next four years, including potential changes to fares at peak periods to spread the load on the rail network and reduce passenger crowding.

Because periods of high demand tend to be limited to travel in one direction, the regulator is weighing up whether peak fares should be limited, for example, to trips towards Sydney's CBD in the morning when trains are packed, or away from the city centre in the evening.

Another option is restricting peak fares at certain locations such as at Town Hall, Wynyard and Central stations in the CBD when overcrowding is a major problem.

Peak hour begins at Town Hall station. Credit:Ryan Stuart

At present, fares on Sydney Trains are 30 per cent lower in off-peak periods than the weekday peaks of 7am to 9am and 4pm to 6.30pm.