Calais (France) (AFP) - On a pitch-black Calais night, a monster 30-tonne truck rumbles along the highway, while a group of migrants, their silhouettes barely visible on the embankment, keep watch.
As the hulking vehicle swallows up the road, dozens of shadowy figures spill onto the asphalt, swiftly placing makeshift barriers in front of the oncoming juggernaut.
It is almost too late when the driver spots the debris and brings the truck to a standstill in a cacophony of screeching tyres and hooting, before trying to reverse in brusque, panicked movements.
This time, no migrants managed to scramble aboard and no one was hurt. The previous night, a 28-year-old Sudanese man was found dead on the city's ring road after being hit by a truck. He was the seventh to die on the road since the start of the year.
The scene is one that will play out dozens more times before dawn breaks in Calais, where thousands of migrants have set up camp and make their desperate bids to reach Britain, just across the Channel from the French city.
"Night after night, we see the highway stormed, barriers erected that stop trucks and allow dozens of migrants to spread out along the side of the road to clamber aboard and try to make their way to Britain," said police unionist Gilles Debove.
"It starts around two or three in the morning and ends around 6:30 am. On the worst nights we intervene every 10 minutes."
While France's migrant crisis is tiny compared with that faced by Greece or Germany, the slum-like "Jungle" camp of about 4,000 migrants has created considerable challenges for locals, truck drivers and security forces on both sides of the Channel.
Many of the migrants have relatives in Britain, or believe they will have a better chance of finding employment there.
The migrants' main tactic has been sneaking onto the back of trucks that cross the Channel aboard ferries, initially when drivers stopped to rest and later by blocking roads and forcing their way onto the vehicles.
The crisis reached a peak in July and August last year when hundreds tried to storm the Eurotunnel site on several consecutive nights.
Security was stepped up in response to the disturbances, thwarting the migrants' efforts, but attempts to block traffic flared again in May.
Recently more and more migrants have been trying to cross the treacherous narrow sea on rubber dinghies.
But on the poorly lit highway, the nightmare continues for truck drivers and migrants alike.
- One 'lucky' migrant -
As the witching hour approaches, migrants gather tree branches, bits of metal and whatever they can find — a dogged, desperate task — before lying in wait.
Police radios spit out calls for assistance: "Barrier erected, junction 47".
Just before 4:00 am, an unmarked police van spots a group of migrants building their umpteenth barricade, and officers set off a volley of teargas.
The migrants strike back, and various projectiles rain down on the officers.
As daybreak looms, the migrants grow more desperate and rebuild a barricade three times in the same spot, but truck drivers manage to force their way through.
A little later, a truck gets stuck and within a few seconds is surrounded by a group including women and teenagers.
Dozens try to clamber onto the vehicle and find a hand-hold, but most fall straight back onto the road.
Only one person appears to have succeeded, sneaking into a space behind the driver's cabin.
However the migrant could still be thwarted further on, detected by heat scans the truck undergoes before it boards the ferry.
At dawn, recounts Debove, migrants emerge from behind embankments, bushes and ditches with their hands in the air telling police: "We go back 'Jungle'".