The firm will start improvements to the Bean and Ebbsfleet junctions in March next year, subject to the successful outcome of a public inquiry.
According to estimates by information specialist Glenigan, the win was the largest of five civil engineering jobs secured during the month, together worth more than £220m.
Morgan Sindall came in second with a £197m haul of work, including a £37m school in Haverfordwest and a £21.7m refurb job at University College London’s Bedford Way building.
Its October tally of orders also impacted on the top rankings in the annualised league, with Morgan Sindall deposing rival Kier to lead the ranking of contractors for the first time this year.
Among the other big contract wins during the month, Tarmac subsidiary Alun Griffiths secured the St Austell A30 Link Road job in Cornwall worth £85m.
Mace was confirmed for the £120m next phase of Land Securities’ big Nova office scheme near Victoria station in London.
While Dutch greenhouse specialist BOM Group secured a £120m project to construct two of the UK’s largest greenhouses near Norwich and Bury St Edmunds.