Britain's creaking transport system could threaten the health of the UK economy, according to the CBI business group.
Congestion is getting worse, the CBI says
And it warned the British public could face "another decade of transport misery" unless the government gets its transport plan back on track.
In an assessment of the 10-year transport plan, the CBI said it had failed "on delivery and as a solution to congestion".
"Congestion on key parts of the road network is worse than before the plan and performance on the railways has yet to return to the levels of the late 1990s," said CBI director general Digby Jones.
"As a result businesses lack the confidence they need to make investment decisions that are vital for future growth and the continued economic success of the UK."
The government's transport plan covers a wide range of measures including the modernisation of the main west and east coast rail lines, the widening of 360 miles of trunk roads and more bypasses to relieve congestion.
While the CBI accepted that some projects had been completed "the perception is that they have made little difference to the daily experience of most transport users", Mr Jones said.
"Ministers need to show resolve by reinforcing the plan," he added.
"It's behind schedule and, even if completed, it won't now reduce congestion but abandoning it would be worse. That would just sentence users to another decade of transport misery."
The CBI called on the government to make improvements which would improve matters in the short-run, such as better use of rail capacity.
It also asked for a commitment to speed up planning decisions for major projects.
Mr Jones said the government needed to realise that transport mattered just as much as health and education.
"To be globally competitive and to become more productive UK business needs to get its goods to market and people to work," he said.
"Business and public alike need the government to deliver."