Train companies want a "swift and rigorous" review of all planned rail investment ahead of expected cuts.
The Association of Train Operating Companies says it accepts the £8bn earmarked for projects may be affected by the "unprecedented situation in the public finances".
But it has asked the government for involvement in deciding which go ahead.
Projects must be assessed in terms of value for money for both passengers and taxpayers, the companies say.
The government is already carrying out reviews of orders for new rolling stock and how the train franchise system works.
But the Association of Train Operating Companies (Atoc) wants ministers to assess future investment projects at the same time.
In a letter to transport minister Theresa Villiers, Atoc says it accepts the "unprecedented situation in the public finances" warrants a review of commitments, including the £8bn due to be invested in enhancing the rail network over the next four years.
Atoc wants to work with the Department for Transport and Network Rail in reviewing infrastructure projects in time for the Spending Review in the autumn.
BBC transport correspondent Richard Scott said the move was part of the industry's bid to gain greater control over what happened with the railways.
Atoc chief executive Michael Roberts said investment in Britain's railway remained "vital" if current levels of performance and customer satisfaction were to keep pace with demand - expected to double in the next 20 years.
But he accepted public spending was under "severe pressure".
"It is our shared responsibility, across the industry and with the government, to put rail on a more stable and sustainable footing," he said.
"But the unprecedented situation in the public finances means that, on balance, a swift and rigorous review is in the best interests of taxpayers, passengers and the railway."
The letter also points out that smaller, targeted projects focusing on specific problem areas can produce benefits for passengers as well as providing good value for money.
The association argues that a more commercially minded approach and a bigger role for companies would drive down costs and make the industry more attractive to private investors.