Sydney's roads were heavily congested in the western suburbs on Saturday evening amid IT issues being blamed for the city's public transport woes, which continued throughout the evening as multiple sporting events got underway in Homebush.

The city's train system was in chaos for most of the day, with passengers stuck on trains between stations, major delays right across the network and travellers being told to simply catch the bus instead.

It led one train driver to vent his frustration to passengers of a lack of information from management. "You won't see our management, but they want you to be reassured by me making announcements to tell you that we have no further information," the driver said. "Thank you."

Sydney Trains said the problems were "a result of an IT issue across all transport agencies".

"This has affected key operating systems that provide visibility of trains and their locations. Technicians are working to resolve the IT issue with systems starting to return to operation across the transport network," a statement said.

Sydney Trains warned people travelling to the 7.45pm Bledisloe Cup match at ANZ Stadium to allow plenty of extra travel time, indicating that the delays could stretch well into Saturday night.

At 6.30pm, Transport Management Centre spokesman Derek Peterson said roads between Burwood and Lidcombe, measuring between six and seven kilometres in distance, were congested in a "heavy" way.

"Parramatta Road is [also] heavier than usual for this time of night," Peterson said. "Homebush Park Drive is also heavy back to Ryde Bridge, as expected with any sporting event.

"The roads around Strathfield train station and shopping centre are also very heavy.

"We have also had bus operators tell us that they have been experiencing delays of up to 30 minutes around many train stations."

Peterson added that "a lot of the congestion is around train stations".

Some train passengers spent more than an hour stranded on trains between stations, after Sydney Trains said it experienced a "technical issue" on Saturday morning that was affecting the entire network.

Sydney Trains told travellers at midday to "delay non-essential travel" or use local buses because services were experiencing "major delays".

There was no indication of when the problem would be fixed, and the delays dragged well into the afternoon.

The chaos was expected to cause issues for sports fans heading to major events across the city on Saturday afternoon and evening, including rugby league and AFL matches.

Road traffic around Sydney Olympic Park was also heavier than usual for a Saturday afternoon, possibly exacerbated by a southbound crash on Homebush Bay Drive affecting travel from Rhodes to the north.

"Due to these issues, communications, real-time apps, information, indicator boards and train running info may be incorrect or unavailable," Sydney Trains said.

People on their way to catch flights or those with urgent medical issues were advised to see station staff for assistance.

Multiple people reported being stuck on trains between stations, with one train stopped near Newtown station and another near Petersham station. Other frustrated travellers waited on packed platforms with no sign of when the next train would arrive.

At some stations, information boards meant to show the arrival time of the next train were simply blank, while at others the screens were blacked out.

Confused travellers described people running back and forth between platforms at Central Station as contradictory announcements were made.

On Twitter, Sydney Trains said there was a "technical issue affecting communications and train running information".

It warned services could be cancelled, terminate early or change platforms at short notice and thanked travellers for their patience.

"Please listen to all announcements and allow extra travel time," Sydney Trains wrote.

"We apologise for the inconvenience caused. Staff are working hard to rectify the issue.

"We are working to return trains to normal running as quickly as possible."

The delays affected the entire network, with a travel alert informing passengers that "technical issues" were impacting the T1 to T8 lines and intercity services to Bathurst, Lithgow and Newcastle.

Travellers trying to avoid the train chaos by using ride-sharing services were also hit, with surge pricing being experienced in the vicinity of train stations in parts of the city on Saturday afternoon.

Passengers branded the situation a "massive system failure", a "meltdown" and an "utter shambles".

The delays came after "urgent" wiring repairs at Wynyard which led to trains being suspended in both directions between Wynyard and Central earlier on Saturday morning.

Seven News reported passengers had to evacuate their train at Wynyard and walk through the tunnel on Friday night.

A new timetable was introduced late last year, and was partly blamed for widespread delays and cancellations on Sydney's rail network in December and January. Sydney Trains has since cut some train services to make the timetable more reliable.

Things were made worse for passengers travelling to the airport from the south, with services diverted via Sydenham after an object was caught in overhead wiring, though they were resumed around 5.30pm.

In that incident, only Northbound T8 services were affected, allowing travellers to reach the airport by changing directions at Central.

Saturday's rail problems coincided with thousands of spectators heading to major sporting events across Sydney on Saturday evening.

The Sydney Swans were due to take on the Greater Western Sydney Giants at Spotless Stadium at 4.35pm, before the Wallabies played the All Blacks in the Bledisloe Cup clash at ANZ Stadium at 7.45pm.

In rugby league, Penrith was set to play Newcastle at 3pm at Penrith, the Wests Tigers were tackling St George Illawarra at 5.30pm at Leichhardt Oval, and the North Queensland Cowboys would face Cronulla at Shark Park.