The impact of Brexit on freight traffic is to be investigated by MPs amid continuing concerns that Kent could be regularly gridlocked after next March.

The transport select committee is to assess the potential challenges facing the freight industry after Brexit amid concerns that too little progress has been made to prepare for exiting the EU.

Much of the freight traffic comes through Kent, with the Port of Dover handling more than 2.6m lorries last year, up nearly 10,000 on 2016.

The MPs are to examine the potential effects on UK freight operations and assess “the preparatory steps operators, their customers and the government need to take.”

Committee chairman Lilian Greenwood MP said: "We've heard a lot about custom arrangements, border controls, tariffs and trade deals.

"But we haven't heard enough about transport infrastructure, policy and regulation implications affecting freight operators and their customers.

"But from day one after Brexit, we will expect our goods to turn up and for life to continue as normal.

“While the agreement of a transitional period to December 2020 is welcome, there remains a great deal of uncertainty for UK freight operators and their customers.”

There is concern that Kent’s road network could be severely hit if arrangements for new customs checks are not in place by the end of March next year.

If not, it has been estimated checks on individual lorries could take so much time that it will gridlock the county.

Industry experts say adding an average of two minutes to customs processing would lead to a 17-mile queue from Dover almost back to Ashford.

Dover MP Charlie Elphicke said: “Hauliers say we need to have resilient roads to the Port of Dover and Channel Tunnel.

"That means fully dualling the A2 and having more lorry parking facilities along the M20.

“These firms also want more certainty and guidance from the Government on the practical effects of Brexit – so they can start preparing now.”

The government says its contingency plans include the use of the former Manston site as a holding area for HGVs but has not yet set out other options which could involve using the M20 at the same time as keeping it open for traffic.

Transport Secretary Chris Grayling has downplayed potential problems.

On a recent visit to Ashford, he said: “We will have interim solutions in place for 2019 which I hope won't be necessary because we will have a sensible free trade agreement.”