Britain's Busiest Motorway

In episode one, we meet traffic officers Simon and Gary on their early morning patrol shift as they are faced with a four car pile-up that has closed two lanes of the motorway during rush hour.

Meanwhile, fuelled by tea and toast, control room operator Emily is part of a team keeping a watchful eye on the motorway with the help of more than 1000 CCTV cameras. After two consecutive traffic collisions in the Dartford area, the pressure is on.

This week, traffic officers Steve and Grant are sent to attend a vehicle on fire, but the danger they face is out of the ordinary. A 90 tonne crane has exploded with its wheels flying into the central reservation, which means that they will have to shut the entire motorway while the fire brigade extinguish the blaze.

Traffic officers Sam and Phil attend a three-car accident, but while they are trying to remove the vehicles from the carriageway, a fully loaded 44 tonne truck speeds down the hard shoulder breaking the roadblock. Meanwhile, Jason and his maintenance team are cone-ing off a slip road and dealing with reckless high-speed drivers trying to get off at the junction with only inches to spare.

In episode three, it's bank holiday weekend and with a heat wave on its way, there are record numbers of vehicles expected on the roads.

As the big getaway begins, traffic officers Howard and Tim are called to a big pile up in heavy traffic. At junction 4 of the M20 a truck has hit a pedestrian bridge forcing it to collapse onto the carriageway. As a result, the M20 has to be closed - adding hours onto holiday makers' travel times - and for Highways England, it's a race against time to get the road re-opened before over a million holiday makers start their return journeys. For the maintenance teams, this means working through the night to get the bridge off the carriageway.

In episode four, traffic officers Ray and Brian have been called to a truck v car collision. The car driver is unhurt and unfazed, but the truck driver is not happy. Meanwhile, traffic officer Simon and team manager Kevin find some illegally parked truck drivers on the side of the motorway and Kevin finds it hard to make himself understood.

Nearly 30% of all traffic collisions on the M25 happen in wet weather. And in episode five, an unexpected thunderstorm has hit the region, dropping two weeks' worth of rain in just three hours. The huge amount of water has caused a flood at junction 21 covering one entire carriageway and Highways England are forced to shut the motorway. Fortunately, traffic officers Keith and Andy and team manager Kevin are on hand to deal with the situation.

It's not only bad weather, which can cause problems on the motorway. Another unexpected problem is animals. They might look cute from the road when they are on the right side of the barrier, but when they're on the motorway they can cause mayhem.

The M25 lies on the edge of London's green belt and with so much wildlife nearby, traffic officers need to know how to handle them. So today, Simon, Kevin and Andy are sent off for horse handling training, and they are not exactly filled with excitement about the prospect. But it's not long until Simon has to put his training into action when a horsebox breaks down in the middle of the motorway.

In episode six, as traffic officers Andy and Keith clock on for the late shift, reports come in of a cupboard on the carriageway. Last year, there were more than 2000 call-outs to items in the road, which can pose an obvious risk to drivers. When they get to the location, it is clear that what was a cupboard is now debris spread across the carriageway. Removing debris is dangerous even in daylight, but with the speed of traffic increasing by over 10mph and visibility dramatically decreasing at night, after dark this job is even riskier.