The project will see a disused railway brought back into use, with new stations built in Pill and Portishead. The line was closed in 1964.
The £6.14m contract is funded by the government’s Restoring Your Railway fund, the Department for Transport, West of England Combined Authority and North Somerset Council.
Planning consent was granted in November last year.
Over the next 12 to 18 months the project will complete the detailed design phase, as well as ground and ecology surveys and enabling works, while preparing the full business case for decision makers.
VolkerFitzpatrick operations director Paul Lilley said: “I am delighted that Network Rail has chosen to work with VolkerFitzpatrick to deliver this important project, including the new stations on this revitalised line. Our team is excited to be part of these plans to connect communities, create a better-connected transport network and support the region’s ambition to be net-zero carbon by 2030.”