Kent's roads are expected to be gridlocked over the next few days - as children break up from school and security is stepped up following the Nice attack.

The influx of vehicles heading to the Port of Dover or the Eurotunnel link at Folkestone causes summer traffic problems every year.

But it has been exacerbated by increased security checks at ports following the attack in Nice.

Now the Freight Transport Association has joined in the warnings ahead of 'Black Friday', before 14 million vehicles hit the nation's roads across the weekend.

Highways England has also issued warnings for drivers to plan ahead and allow plenty of time for travel as Kent's roads get busier in the coming weeks.

The authority has advised on alternative routes for drivers to use as the M2 and M20 are expected to get very busy.

Tourist traffic for Dover is advised to use the M2 and A2, whilst freight traffic should use the M20 and A20.

Local traffic meanwhile is being told to use routes such as the B2011, A256, or A258, which are not as suitable for HGVs.

Drivers are also advised to check travel conditions before setting out, and to ensure that their cars are fit for the journey.

Port bosses are offering a free transfer to another ferry if they miss the one they booked due to extra checks.

The Port of Dover alone processed more than 13 million passengers last year - eight million of whom passed through between April and September.

Motorists have become concerned this week by the appearance of signs showing Operation Stack is not in action, amid concerns it will soon be put in place.

Op Stack caused major disruption last year, with trucks queuing in two lanes of the M20 between junctions 8 for Maidstone and 11 for Canterbury and Hythe.

Trucks were separated into lanes depending on whether they were going to Folkestone for the Eurotunnel or the Port of Dover for ferry services.

Other traffic was diverted off the M20 at junction 7 for Maidstone and Sittingbourne, and down the A249 to join the M2 at junction 5.

This caused further disruption in the county as traffic found an alternative route down the M2 to junction 5 for Canterbury and the A2 to Dover.

So far this year, Operation Stack has not been put in place, and Manston has not had to be used.

However, drivers are being warned to expect delays on the approach to the ports in both Dover and Folkestone following the attack in Nice last week.

Additional security checks have been put in place by French border control following the attack, which is slowing processing down at the ports.

A port spokesman said: "The port, together with its ferry partners, prepares each year for the summer getaway.

"Operation Stack is only used as an emergency measure following a thorough assessment of the safety concerns and disruption on the road" - Kent Police

"Of course, it is a busy time of year, but we are used to dealing with these volumes of traffic.

"What we are now faced with however, following the attacks in France, is the heightened security at the French border controls at the Port of Dover, which is delaying traffic from being processed through the rest of the port."

They added: "We are utilising 4km of additional capacity we have invested in the port to help keep Kent's roads clear, along with the valuable deployment of Dover TAP on the A20 to control the flow of freight traffic through the town of Dover.

"We would advise customers to allow plenty of time for their journey, to have their passports ready to speed up processing, and to ensure they bring plenty of water when waiting to go through French border security during these particularly hot summer days."

Dover TAP, or Traffic Assessment Project, is a scheme that was given public backing at a recent Port and Community Forum in Dover.

The scheme will hold lorries outside the town on the A20 to ease congestion in Dover during busy periods.

Natalie Chapman, head of policy for the Freight Transport Association in the south east, is keen to endorse this scheme.

She said: "Dover TAP means that trucks may be queuing outside Dover so it can continue to function as a town. We hope that everything will continue to run smoothly.

"We are telling freight workers to allow extra time, and I think that is something that we would encourage holiday makers to do as well," she said.

Holidaymakers worried about missing their booked crossing have been reassured today by ferry company P&O.

A spokesman said: "We can confirm that additional border checks have been introduced, and as a result passengers are encountering delays.

"We are doing everything we can to allow passengers to begin their journey as quickly as possible.

"If passengers miss their allocated ferry, they will be able to board the next available ferry, at no additional cost."

The M25 is one of five motorways highlighted by the Freight Transport Association as expected to bear the brunt of the traffic.

Malcolm Bingham, FTA head of road network management policy, said: “Planning ahead of any journey is crucial for all drivers – particularly when so much traffic is expected on the roads.

"FTA encourages its members to use all the information available to avoid traffic jams as they attempt to make their routine journeys and deliveries.

“Delays cost money for the industry; it costs £1 a minute for a 44-tonne HGV to stand still in traffic and there is also the knock-on effect when contracts can’t be delivered on time and deadlines are missed."

Last year's problems with Operation Stack have widely been blamed on industrial action in Calais by French workers, as well as the migrant crisis.

Due to the volume of lorries queuing, Manston airfield was made available as an emergency lorry park, but was only ever used in a test.

Although a new site for a lorry park has now been agreed, it will not be open until 2017.