A21 Tonbridge to Pembury dualling

Charlie Stewart

A21 Tonbridge to Pembury dualling

Upgrade of the A21 to a 2 lane carriageway between Tonbridge and Pembury.

Scheme stats

Region: South East
Start date: April 2015
Cost: £69.7 million
Type: Major Scheme
End date: March 2017
Project status

Progress report

We have undetaken construction work in the southern section (Pembury Walks to south of Longfield Road and the new Longfield junction), the central section (Castle Hill to Pembury Walks) and the northern section (Vauxhall to Castle Hill). This work included:

  • drainage
  • earthworks
  • construction of new pavement
  • construction of new bridges

What next?

The next phase of works will be taking place from mid-August to facilitate the construction of the Longfield road junction. These works will involve the closure of Tonbridge road between Pembury hospital and the existing Longfield road roundabout with traffic traveling on the new slip roads and roundabout which is located to the west of the existing Longfield roundabout.

Access for Pembury hospital and the local businesses will be maintained via the A228 and the Pembury end of Tonbridge road. Highways England and Balfour Beatty have been working with our stakeholders including Kent Police, Kent County Council and the local hospital to agree on emergency access provision and alternative route in advance of this closure.


Date Event
December 2009 Orders published
October 2010 Spending review
May 2012 Funding announced
May 2013 Public inquiry
May 2014 Secretary of State announcement
April 2015 Start of works
March 2017 End of works

Why we need this scheme

Between the M25 and Tonbridge the A21 is a 2 lane carriageway standard with grade separated junctions, limited access and no central reserve gaps. Between Tonbridge and Pembury the standard drops to single carriageway with poor horizontal and vertical alignment and many individual accesses to properties, farm fields and woodlands. Approximately half way along the scheme there is a petrol station on the east side and junctions with two minor roads, Dislingbury Road and Pembury Walks, either side of the petrol station. This causes traffic congestion and delays on the A21, particularly due to right turning traffic. There are no footways and verges are either very narrow or non-existent.

This single carriageway section of the A21 experiences severe congestion throughout the day and particularly at peak times and has a poor accident record with an average accident rate (expressed as accidents per million vehicle kilometres) about 20% higher than the default value for a road of this type.

The scheme in details

The new dual carriageway will broadly follow the line of the existing A21 with a new junctions at Fairthorne (by the petrol station) and at Longfield Road, replacing the existing roundabout at the southern end of the scheme. At the northern end, there will be a minor change to the line of the slip road from the Vauxhall Lane roundabout where it joins the A21.

Parts of the existing A21 will be retained to provide access to houses, businesses, fields and woodland. A new bridleway for pedestrians, cyclists and horse riders will be provided along the whole length of the scheme. A new footbridge will be provided across the Pembury Bypass at Blackhurst Lane, replacing the existing crossing.


The main objectives of the scheme are to:
  • relieve congestion
  • improve safety for all road users
  • improve journey time reliability
The environmental objectives of the scheme are to:
  • mitigate the impact of the scheme on the AONB
  • minimise the adverse impact on the RSPB reserve and the Scheduled Ancient Monument
  • minimise the impact on ancient woodland

Environmental impact

We have surveyed the local area to assess the effect the scheme will have on the landscape and on plant and animal life. The results of the surveys and the measures we propose for reducing the effect of the scheme are contained in the envrionmental statement and are summarised in the non technical summary of the environmental statement. The link to these documents can be found on the ‘publications’ tab.

During construction we will use best practice to safeguard the local environment and will plan the construction works to minimise adverse effects on the local community and the environment.

Ancient woodland

The scheme entails the unavoidable loss of 9Ha of ancient woodland for which 18Ha of translocated and planted woodland will be provided in mitigation. These areas will be managed for 25 years. In addition, 27Ha of existing woodland will be managed for 10 years while the new planting becomes established.

Local communities and land use

Parts of the existing A21 will be retained to provide access to houses, businesses, fields and woodland. Earthmounds and planting will be used to screen the A21 from properties, with noise fences included where they will be effective.

The scheme will require additional land, most of which is good quality arable farmland or woodland. Four houses and 1 barn will need to be demolished to build the scheme.

A new route for pedestrians, cyclists and horse riders will be provided along the length of the scheme, and an additional pedestrian and cycle bridge provided at Blackhurst Lane to facilitate access to Pembury Hospital.

Noise and vibration

Noise fences and earth mounds with planting will be provided to ensure that all residences currently close to the line of the existing A21 experience a reduction in noise level. Other areas further away from the A21 may experience a negligible increase in noise levels.

Air quality

The majority of affected residential properties may experience improved local air quality as a result of the scheme proposals and because of the reduced traffic congestion. Air pollutant concentrations at properties near to the road will not exceed the levels that are set to protect human health.


Substantial areas of trees, shrubs and grassland will be planted, with the intention of fitting into the existing pattern of hedgerows, woodlands and pasture fields. Native species that are local to the area will be used where possible. The new junctions and road bridges will initially be intrusive features of the scheme but over time the extensive planting will create effective screening.

Wildlife and nature conservation

The Tonbridge to Pembury section of the A21 comprises a variety of habitats including woodland, hedgerows, grassland, streams and ponds.

Protected species found during our surveys include bats, dormice, badgers, breeding birds, great crested newts and reptiles. Although areas of woodland will be lost to the scheme, a wide variety of mitigation measures have been included to limit or compensate these impacts. The project team has consulted with statutory bodies to ensure that with mitigation the long-term effects on most species will be neutral, and the character of the landscape preserved.


The existing water environment will be protected by using drainage balancing and treatment ponds and facilities to contain pollutants. These measures will improve the quality of the water draining from the road system and ensure that there will be no increased risk of flooding in the area.

Historic environment

The scheme runs through the High Weald an area inhabited by man for at least 6000 years. There is evidence of Iron Age, Roman and Medieval activity in the wider landscape. The High Weald landscape is formed of small fields and woodlands dating from Medieval and Saxon periods and the scheme has been designed to retain this historic form of the landscape.

So that the scheme has no effect on the Castle Hill Iron Age hillfort it will be necessary to demolish a Grade II listed farmhouse and barn. As a condition of the planning consent we will photograph and record the buildings before demolition and the barn will be carefully taken down and re-erected at a historic buildings museum.

The farmhouse itself is not unique and has been altered a lot during its lifetime, so does not warrant re-erection.


Castle Hill brickworks preservation by record, where we photographed, sketched and recorded in detail our findings was completed.

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