The firm saw its portion of total spend jump 60% from £337m to £541m in 2016/17.
The uplift saw Costain’s total slice of the spending pie rise from around 5% to 7.4%.
Carillion Construction also retained its second ranking this year achieving a 6% uplift of work.
ABC Electrification benefitted from the focus on electrification work across the rail network with its invoiced revenue almost doubling to over £200m.
The top 20 suppliers shared out £3.69bn, up from £3.1bn previously, which accounted for half of Network Rail’s supplier spend.