Octavius is a leading UK civil engineering and electrification transport infrastructure businesses with over 700 employees working across rail and highways.
It was originally part of the Osborne Group but was sold to investment group Sullivan Street Partners in 2021.
Latest results for Octavius for the year to March 31 2025 show pre-tax profits jumped to £8.6m from £4.7m last time on turnover up to £323m from £277m.
The business has long-standing relationships with key customers in the sector such as Network Rail, National Highways, and Transport for London, and has a portfolio of over 30 frameworks.
Current projects include the refurbishment of Ryde Pier on the Isle of Wight and Waterloo Station Roof, the construction of new railway stations at Okehampton and Charfield, the A46 Walsgrave Junction Upgrade, the construction of a new link road in Colchester and the completion of the newly opened A140 Long Stratton Bypass.
Octavius will continue to operate under the leadership of Chief Executive Officer (CEO) John Dowsett, who will remain fully supported by his executive team, which includes Matt Smith and Gavin Pritchard, managing directors for the rail and highways sectors respectively.
The addition of Octavius marks a pivotal step for RSK in the transport infrastructure sector which currently accounts for 14% of its total revenue.
Octavius CEO John Dowsett said: “I am very excited about joining the RSK Group and embarking on the next stage of the Octavius journey. Having thrived under the ownership of Sullivan Street Partners, expanding our capabilities, reputation, revenue and profitability, RSK feels like the natural long-term home for us to continue our ambitious growth plans.
“We will retain our proud Octavius brand and maintain a strong level of autonomy, while enjoying a wealth of support from the considerable expertise within the RSK Group.
“We have a strong cultural fit with RSK, with complementary strengths, and share a vision for ambitious but sustainable growth, delivered with an unwavering commitment to the safety, health and wellbeing of our people and our environment.
“I am looking forward to working closely with the RSK leadership team and our partner businesses to deliver the Octavius vision of being the most respected transport infrastructure provider.”
RSK Founder and CEO Alan Ryder added: “I am very proud to see Octavius, a high quality and trusted partner in the UK rail and highway sectors, choose RSK as its long-term home. John and his team have built a remarkable business, and I look forward to working with them as they continue to lead Octavius through many more successes.
“Infrastructure is one of RSK’s core strategic growth markets and, in Octavius, we have found a large, well-established business with a proven track record in safety-critical infrastructure delivery. With many complementary businesses already in the group, we see significant opportunity for collaboration, further improving the value we can bring to our shared client base.”
