The junction is at the top of Blue Bell Hill, on the A229 between Maidstone and Chatham, close to junction 3 of the M2 motorway.
Aecom will deliver the broad design for a new road scheme that will address congestion and safety issues. Kent County Council has budgeted £140m for the project.
Aecom was appointed as part of its role on a new professional services framework with the council, valued at £25m over the three-year term.
Aecom framework director Richard Carpenter said: “Tackling traffic bottlenecks and improving safety at Blue Bell Hill will make a huge difference to communities in Kent. We are proud to bring our transportation expertise and track record to shape a solution which will leave a lasting beneficial legacy for those who live and travel around Blue Bell Hill.”
The framework is a multi-supplier, multi-disciplinary contract for professional services. Kent County Council Cabinet Member for Highways and Transport Michael Payne said: “This is good news for Kent. Through this new contract we can get access to the best technical advice and innovation in the industry at very competitive rates whilst helping local business.”