The £20million make-over of Heathrow’s southern runway is one step closer, after the completion of the replacement of the asphalt surface, and the start of the final installation of the new lights and cabling.

After a decade of continuous pounding by millions of aircraft taking off and landing, the runways at Heathrow are undergoing vital refurbishment to ensure they are safe and in good order.

As the airport cannot close a runway during the working day, the logistically complex operation happens during the night and on one runway at a time.

The work began on the southern runway in April; the northern runway will be resurfaced next year using the same process.

Over 150 construction workers using approximately 80 heavy items of plant and equipment have worked for almost four months to excavate and relay 22,000 tonnes of asphalt - the runway’s hard-wearing surface.

With this part of the project completed the next phase to complete the installation of around 130,000 meters of lighting cable and over 1,000 Aeronautical Ground Lights began at the beginning of August.

These lights help guide the pilots during poor visibility and are fitted within the surface of the Runway.

During each working night more than 1,000 cones mark out a temporary road system along the length of the runway to allow safe passage of vehicles and machinery.

Work starts as soon as the last flight has used the southern runway and the team then has a race against the clock to complete the work before the next day’s operations begin.

Andrew Mitchell, senior project manager said: “During the July heat wave, we had to reorganise our schedule as it was too hot for the asphalt to be laid, but with careful contingency planning and well co-ordinated teamwork the pace of the project hasn’t been affected.

“We’ve successfully laid and grooved the new surface and now we’re cracking on with laying the thousands of metres of new cable and connecting hundreds of lights.”

Before the day’s first flight the sections of new runway are inspected for debris and a safety ‘grip test’ is carried out.

The runway is only authorised for use once the duty manager airside is satisfied everything is safe for aircraft to operate.

Once the lights are complete, a flight check will be carried out (a small plane will conduct a series on landings on the runway) to make sure all the lights are operating correctly, and then the runway will be returned to its CAT3 status, indicating that the runway can be used in all weather conditions.