St Albans MP Anne Main has again pushed for answers over the feasbility of the controversial rail freight depot planned for a Green Belt site near Park Street.

It remains unclear how the proposed Strategic Rail Freight Interchange (SFRI), which was given outline planning permission in 2014 after years of opposition, would fit with the troubled Thameslink passenger line.

If Network Rail cannot accommodate extra carriages, campaigners fear the SFRI scheme on the former Radlett Airfield will transform into a lorry depot and further clog roads in the Park Street area.

Mrs Main has implored rail minister Paul Maynard to obtain answers on the scheme, adding: “For years Network Rail has been silent on this issue.

“Even now at the last moment, we still have no idea as to how freight will operate on the same line as the passenger services.”

She said it is now six months since people were promised a look at the scheduling strategy.: “This latest episode is the mere tip of the iceberg when it comes to Network Rail’s silence.

“I believe that the lack of preparation and time-tabling seriously calls into question the viability of rail freight. I’ve now asked the minister to call in Network Rail to get answers.”

Mrs Main said: “St Albans commuters have already suffered due to recent train failures and infrastructure upgrades”, and Network Rail was “negligent in its duty” of putting passengers first. She urged the company to to fully explain how they plan to deliver freight and passenger services along an extremely busy stretch of the Midland Mainline.

In April this year Mrs Main asked for an urgent meeting with the Transport Secretary, Chris Grayling, over the plans.

The SFRI has been highly contested since it was originally proposed in 2006 - St Albans district council originally refused the application and took the case to both the High Court and the Appeals Courts after former communities secretary Eric Pickles went against their decision and approved the plans.

Outline planning permission given to the developers Helioslough includes conditions such as the creation of a country park and a relief road in the surrounding area.

Herts county council still owns the land where the rail freight depot is proposed to be built and is obligated to sell if it receives a suitable offer.