A model of the new Croxley Rail Link was presented by Watford MP and transport minister Patrick Mcloughlin.
Mr Harrington invited the secretary of state to Watford to see firsthand the progress that has been made at the site following the Government’s commitment to fund the project just over two years ago.
Mr Mcloughlin said: "The whole thing is about getting the right level of infrastructure.
"That’s very important for jobs too. It’s about getting investment into the area."
However, the minister could not give a definite number of companies committed to coming to Watford as a result of the new transport links.
Mr Mcloughlin continued: "I am reassured a number of companies have expressed interest as soon as we got the infrastructure investment."
Track clearance at the West Watford site, on Ascot Road, is currently underway.
Drainage investigations, surveys of electrical cables and communications cabling and geological investigations are also progressing ready for construction to begin later this year.
Earlier this month the planning applications for the station designs were passed unanimously, and trains are set to be operational on the new Rail Link at the end of 2017.
The new link is expected to ease congestion on local roads, improve access to Watford General Hospital, Watford Football Club and the Watford and Croxley Business Parks. Around 2,700 homes will fall within 800m of a Metropolitan Link Station once the new line is up and running.