Grant Shapps vowed to bin repetitive rail announcements as part of his "bonfire of banalities".
Sources tell HuffPost UK that No.11 officials want savings that could torpedo PM's commitment to Northern Powerhouse Rail.
Over 10 years, there has been a 167% increase.
Collapse of east coast franchise, HS2 and low ticket profits bumped up costs
Transport secretary slammed over 'monumental misjudgement'.
'Ministers must justify their decisions.'
Labour say the cash could have paid for 26 buses.