The £477m plan to finally cure traffic chaos on UK's busiest motorway

Two multi-million pound improvement projects to key parts of the UK's busiest motorway aimed at reducing traffic jam misery are underway.

National Highways hopes to ease flows on the orbital motorway around London through the major construction works at junction 28 in Essex and junction 10 in Surrey.

A £317m huge redevelopment of the M25's junction with the A3 Wisley Interchange is underway with a planned completion date of summer 2025.

It aims to reduce congestion, improve safety, create a smoother flow of traffic and provide safer journeys for thousands of motorists daily.

The junction is the busiest section of the M25, with over 300,000 vehicles travelling through it every day.

This sheer volume of traffic means vehicles often start queuing northbound between the Ockham Park roundabout and the M25 junction 10, on the junction 10 roundabout, and on the approach to the Painshill roundabout.

With the number of users set to increase over the next 10 years, the project will create an additional lane on the A3 in both directions from Ockham and Painshill junctions towards the M25.

There will be a larger roundabout with extra lanes to increase capacity and free-flow left turns at all four corners of the junction.

Improvements to the A245 Seven Hills junction and Painshill roundabout will also facilitate flows, while safer access to Old Lane, Elm Lane, Heyswood campsite and San Domenico will reduce accidents and there will be new and safer routes for cyclists, pedestrians and horse-riders.

The junction is also located among some rare and beautiful habitats including the heathland at Wisley and Ockham commons.

A National Highways spokesperson said: "We'll also deliver environmental improvements, including the restoration of heathland around junction 10, and the planting of new trees and woodland in other areas.

"The A3 will be surfaced with a low-noise material and environmental barriers along the M25 will be replaced. The effects on air quality will be minimised, and local rivers, lakes and ponds will be better protected from pollution and flooding.

"Exploring the area on bicycle, foot or horse will be easier, with new bridges crossing the A3 and M25, connecting the four quadrants surrounding for the first time."

The project includes the demolition of several bridges plus the creation of many new ones, including the UK's first heathland green bridge to reconnect the commons on either side of the A3 and provide a natural and safe corridor for wildlife.

Meanwhile, around £170m is being spent on improvements to junction 28, another extremely busy section in Essex.

It plays a vital role in connecting the A12, which runs through Essex to Norfolk, and the orbital motorway, as well as providing access to Brentwood via the A1023.

Up to 7,500 vehicles per hour pass through the junction roundabout at peak times, making it a key area for bottlenecks during rush hour.

If action to improve traffic flow is not taken, it is likely to worsen over the next 10 to 13 years.

A National Highways spokesperson said: "As it is operating at capacity, vehicles using the junction face congestion and delays, which effects local air quality.

"Our research shows that traffic is expected to increase in the area by around 30 percent by 2037, which means that more than 9,000 vehicles could be passing through it by this date."

The planned improvements to the junction include building a new two-lane loop road, for traffic travelling from the M25 anti-clockwise onto the A12 eastbound towards Brentwood.

This includes the construction of several new bridges to take the loop road over or under the other road links.

It will also involve significant changes to the landscape changing the position of A12 eastbound exit slip road and M25 anti-clockwise entry slip road to allow for the new loop road and widening the M25 anti-clockwise carriageway to provide more space for traffic leaving for the A12 eastbound.

The spokesperson added: "Our improvement scheme will increase capacity and reduce congestion at the junction and on the approaches and exits.

"(It will) improve safety by redesigning the existing roundabout layout and reducing traffic levels, provide better connections between the M25 and A12, reduce annual collision rates through additional capacity (and) improve average journey times and reliability for all passing traffic through the junction."

They said it would also minimise the impact of air and noise pollution in the local area by smoothing the traffic flow, reducing traffic queuing back onto the M25 and helping economic growth in the area by providing improvements to cater for future traffic demands.

It is hoped to complete the works by the end of 2025.