The British Chambers of Commerce (BCC) said the success of the economy depended on improving the transport network.
Crossrail would provide an east-west train travel artery across London while an expansion of Heathrow would provide the economy with a £21.7bn boost, according to the BCC.
BCC director general David frost said: “Transport infrastructure cuts must not become a politically convenient way to slash spending after an election, especially when there are huge savings to be made in far larger budgets, including health, education and welfare.
“A government focused on the UK’s future economic success must do everything it can to protect investment in priority transport projects.”
On spending he added: “Public resources are constrained, of course we understand that, but cutting or scrapping plans for regional transport improvements means fewer jobs, and ultimately fewer businesses driving recovery.”