The performance of the north’s two main rail operators is worse than it was a year ago in the aftermath of the timetable chaos that affected thousands of passengers, a report has found.

The reliability of both Northern and TransPennine rail services has fallen sharply in the last two years and worsened gradually over the last few months, according to the study by Transport for the North.

Rail officials said services had been hit particularly hard by severe weather events such as flooding in the Derbyshire town of Whaley Bridge, train failures and cancellations caused by a lack of staff.

Tom Davidson, a transport planner for Transport for the North, said the worsening services was a “significant concern” going into autumn, when demand traditionally increases and fallen leaves can cause delays.

He said passenger crowding was also a worry for rail officials, with an estimated 114 passengers a day unable to board Northern services because of overcrowding.

The report, published before a Transport for the North rail committee meeting on Thursday, will increase calls for an overhaul of Britain’s ageing rail network.

Northern leaders and businesses have urged the government to commit fully to the vastly delayed and over-budget HS2 rail line and to Northern Powerhouse Rail, a high-speed rail link that would speed up journey times between Manchester, Liverpool, Leeds, Sheffield, Hull and Newcastle.

On a visit to Yorkshire last week, Boris Johnson said he was committing £9bn – “a huge slug of money” – to connecting the big cities of the north with Northern Powerhouse Rail. However, the prime minister was lukewarm about HS2. A review of the plans, commissioned by the government, is due to be published next month.

Manuel Cortes, the general secretary of the rail staff union TSSA, said: “The findings of this report should come as no surprise to anyone. Northern, TransPennine and many other franchises are failing day in, day out. If we had a government that cared a hoot about putting passengers before profit our railways would be brought back under public control right now. The evidence for doing so is compelling – look no further than this report.”

The report found the number of TransPennine trains running on time had fallen to 70.9% from 75.7% a year ago and 89.6% in August 2017. For Northern, the number of trains running on time averaged 79.4% this August, compared with 82.2% in May 2018 and 91.2% in August 2017.

A spokesperson for TransPennine Express said: “Last month our customers experienced some disruption to their journeys. This was due to a number of factors, the most significant being weather events such as flooding and extreme heat. Performance has improved this month and we are working hard to ensure that we continue to provide the best possible service for our customers.”

A Northern spokesman claimed its performance had been “steadily improving over the past 12 months”, but added: “We know there is more to do, and our customers were impacted over the summer by extreme weather causing flooding and damage to overhead lines and disruption to many rail services across the country.

“Northern is delivering the biggest transformation of local rail for a generation, with 18 of our 101 new trains already in service and driver training on a further 20 trains taking place right now.”