An increase in train services has reduced the rail network's ability to make up time after major incidents causes delays. Credit:Nick Moir Sydney Trains lists among the challenges of the timetable changes a reduction in the "reliability buffer" from extended dwell times of trains at stations; and more complex operations at Parramatta. Among the "customer risks" Sydney Trains identified were complaints from passengers travelling to Westmead Hospital, following a halving of services to Westmead station, from 12 to six, during the morning peak. The 52-page document, obtained by Labor, was prepared before the timetable overhaul a week ago, which resulted in an extra 771 weekday services and another 800 services at weekends. While tens of thousands of commuters stand to benefit from more frequent services, it highlights the growing pressure on an already stretched rail network and its limited ability to recover from delays caused by major incidents such as breakdowns.

Patronage on Sydney's train network has surged over the past year. Credit:Peter Morris Labor's transport spokeswoman, Jodi McKay, said it was clear from the document that the knock-on effect of the timetable changes was that it "won't take much to send the network into a meltdown". "Once again the travelling public is only hearing what [Transport] Minister Andrew Constance wants us to hear about his new timetable," she said. Passengers endured significant delays and cancellations of train services across Sydney's rail network at the weekend due to urgent equipment repairs at Ashfield in the inner west. A Sydney Trains spokesman said it had delivered the largest increase in services ever experienced in NSW, and an on-time running figure of more than 97 per cent.

"This success is a result of extensive planning in the run-up to the launch of the timetable. While unforeseen incidents can sometimes cause delays, we are confident we have everything in place to help minimise any potential impact on our customers," he said. To cope with surging demand, the Berejiklian government is spending about $20 billion on a new metro train line from Sydney's north-west to the CBD and Bankstown, and has committed to building another line between the CBD and Parramatta. A key aim of the timetable overhaul has been to "release capacity for growth on the Western Line". Services have been increased on the South and Bankstown lines to cater for patronage growth and the passengers transferred from the Western Line. The government has repeatedly warned that a forecast surge in demand means that the Western Line will be unable to carry more passengers by 2031.

The latest timetable changes mean trains on the T1 Western Line no longer stop at Harris Park, Granville, Clyde, Auburn and Lidcombe during periods of the day. As a result, commuters at those stops have to rely on T2 South West services. The leaked document outlines potential risks to the reliability of services on the Western Line during the morning peak from "more complexity" at Parramatta, trains operating at "track capacity" and a greater workload for signallers making it "harder to recover" from delays. Separating services on the Western Line from those on the South Line between Granville and Homebush "simplifies operations on good days" but reduces the "flexibility to recover from delays with diversions", it says. And in a sign of the potential ripple effects, it reveals operating 20 trains per hour through Sydney's CBD and the north shore "will depend on [the] merge [of trains] at Westmead and management of dwell [times] at Parramatta and Strathfield". Wynyard and Strathfield are the only stations where the length of period trains are at a stop at platforms has increased due to the timetable changes.

However, the Sydney Trains document shows that limiting dwell times to 30 seconds at medium-sized stations "will be challenging". Trains spending longer periods at platforms adversely impacts the reliability of services and the network's capacity, as well as coping with routine delays. Loading The standard dwell period for trains at the city's stations is 30 seconds, about two-thirds of which is needed to open and close train doors. The reliability of services improves by about 5 per cent during the school holidays due to fewer people getting on and off trains, resulting in shorter dwell times.