Pressure is being piled on Network Rail to explain how rail freight and commuter trains can operate in harmony if a massive interchange is built in Park Street.

St Albans MP Anne Main has been highly critical of Network Rail (NR) - responsible for rail infrastructure - over what she sees as its failure to explain how it will overcome timetabling concerns relating to rail freight using passenger routes to get on to the Strategic Rail Freight Interchange (SRFI) which has planning permission for construction on the former Radlett Airfield.

And she also questions the current demand for rail freight in light of analysis the Office of Rail and Road’s national quarterly statistics which appears to show the rail freight industry is in decline.

In a letter to Mark Carne, NR chief executive, she says: “Assurances must be made to avoid the SRFI becoming a mere lorry park.”

Mrs Main points out that in the decade since the initial proposals for an SRFI at Park Street first emerged, passenger services on the routes which will be used by freight traffic serving the interchange have increased while demand for rail freight has declined.

She questions how NR will overcome the conflict between the timetabling of passenger trains, which anticipates demand, and the timetabling of rail freight which responds to demand.

And she also asks how NR plans to guarantee that rail freight services will not require access to passenger routes at peak times.

Pointing out that increased rail freight activity on the Midland Main Line is integral to the success of the SRFI, she says that it is ‘substantially less desirable to rail freight services’ than East or West Coast Main Lines, both of which have a gauge of 10.

The MML has a gauge of eight between London and the SRFI site which limits the size of container that can be handled.

On the issue of demand for rail freight, Mrs Main asks if NR has reassessed its national strategy recently in light of the reduction in the volume of commodites moved by rail.

And because an earlier inspector’s report into the SRFI suggested that rail would not be commercially effective against road movements from such deep sea ports as Felixstowe and Southampton, she asks Mr Carne if NR shares her concerns that the SRFI will be uneconomical given its location.

Calling on NR to provide ‘swift and detailed answers’ to her questions, she says the issues are of fundamental importance to ensuring that rail freight does not disrupt her constituents’ daily travel to work and that the SRFI will be viable into the future.