Dartford Expressway: A better solution

The Dartford Expressway is a pair of motorway-grade tunnels, three lanes in each direction plus a hard shoulder, carrying the M25 below ground from south of junction 2 to north of junction 30, completely and invisibly bypassing Dartford. 


Dartford Expressway Portal

An artists impression of what the approach from the south might look like.


The Lower Thames Crossing is promised to solve the traffic congestion at the Dartford Crossing. The existing crossing (the A282) comprises the Dartford Tunnels which carry all M25 anticlockwise traffic (northbound) and the Queen Elizabeth II Bridge which carries M25 clockwise traffic (southbound).

According to Highways England’s figures, only 30% of traffic using the Dartford Crossing is local, the remainder in regional or national with no interest in destinations or local roads within the Dartford area. 70% of traffic needs to be able to pass through Kent without touching the sides.

(dust) The west and east tunnels, completed in 1963 and 1980 respectively, no longer meet modern design standards such that vehicles taller than 4.8m are restricted to the newer east tunnel.  Vehicles carrying hazardous loads must be escorted through the tunnel for safety reasons, so traffic lights halt ALL M25 (anticlockwise) traffic for several minutes each time a lorry needs to be escorted through the tunnel.

Yes! There is a set of traffic lights on London’s Orbital Motorway!

As a result, it is quite usual for traffic to queue back beyond junction 3 at Swanley some six miles to the south.

To add to the problem of HGV drivers having to change lanes to use the east tunnel, there are numerous entries and exits from the orbital motorway all very close together causing driver confusion and further lane changing as drivers find the correct lane for their destination. This turbulent traffic flow leads to a high risk of traffic collisions resulting in frequent major delays.

It should be noted that in stretches of motorway where traffic is able to flow in a more even laminar way for long distances in the absence of restrictions such as entries and exits, the risk of traffic collision is much lower and as a result traffic flows more smoothly and more quickly without incident. This is the original motorway design principal.

In the event of an incident at the Dartford Crossing or even at times of heavy traffic, the local road network in the vicinity becomes burdened and often grid-locked with traffic attempting to find an alternative route, or to queue-jump to access the Dartford tunnels. As a result, residents of Dartford and the surrounding area suffer very poor air quality from exhaust and particulate matter (dust) pollution.

The Lower Thames Crossing Association thinks that it is unacceptable that London’s Orbital Motorway has never been completed to motorway standard at Dartford and that there are no published proposals to do so.

It must be a top priority to solve the traffic congestion and pollution problems at Dartford BEFORE embarking upon any investment in new roads.

Highways England Route Selection

The Dartford Expressway proposal by the Lower Thames Crossing Association was born out of one of the options within Location ‘A’ at Dartford that Highways England considered but summarily discounted early in their route selection process.

Figure 3.1 - Location A - All route options

This option was designated as “A14” in their consultation material and was described as:

“A14 – Long tunnel south of Junction 2 to north of Junction 30.”

Option A14 is depicted with a green dotted line in Figure 3.1.

The key reason for their decision not to shortlist this option was:

“Cost approximately more than twice A1. Poor level of economic benefit due to limited attraction of traffic.”

Pre-consultation scheme assessment report – identification and description of shortlist routes, Table 3.3, page 10.

How Highways England can claim Option A14 has “limited attraction of traffic” is beyond our understanding given that is has been stated the Dartford Crossing is operating well over its designed capacity. The demand for a Dartford Expressway (Option A14) is already there, pent up, on the M25.

Having discounted all other route options including Option A14, Highways England selected Option C3, the current proposals for a new A112 road between the A2 at Cobham and the M25 in Essex taring through 14 miles of prime agricultural green belt land.

Department for Transport Decision

On 04 October 2021, Baroness Vere of Norbiton, Minister for Roads, Buses and Places stated in her letter to Adam Holloway MP:

“I should clarify for your constituent that the decision to proceed with the Lower Thames Crossing was taken by the Secretary of State and not National Highways. Congestion relief at Dartford was not the sole criteria for a new Lower Thames Crossing; connectivity and wider economic impact were additional and important considerations when the Department consulted on the creation of a new Lower Thames Crossing and contributed to the decision to proceed with the current project over other potential options.”

It could be deduced from this that the Department made the decision to proceed with little or no regard for Highways England’s recommendations or the feedback received from the public during several consultation exercises. It must be questioned whether the decision to build a new crossing east of Gravesend was made long before the project brief was given to Highways England to develop. If so, that decision was made without due regard for the impact on the traffic network, our daily lives, or the environment. It was made for principally economic reasons; nothing to do with traffic congestion relief or fixing the problems at Dartford, which are a convenient device to support the Department’s case for their plans. This opinion is also given weight by the sheer lack of any detailed analysis by Highways England of the many possible Options in Corridor A which get hardly a mention in the consultation material.

The fact is that, as mentioned in the Minister’s letter, other potential options exist. These have been discarded in favour of Option C with total disregard for the consequences.

The Consequences of Option C

Highways England claims that their proposals will solve the problems at the Dartford Crossing. The Lower Thames Crossing Associated and partner campaign groups agree that if anything the proposals will make the traffic congestion and pollution situation worse, not better.

The technical road layout designs for the proposals are subject to several physical constraints, most notably at the junction with the A2 at Cobham where the HS1 railway limits the building of road structure on the south side of the A2.

The design Highways England has come up with has serious consequences for the existing trunk and local road network. The most significant issue for north Kent is that that the design reduces the A2/M2 from 4 lanes to just 2 in each direction at a pinch point between the Shorne and Gravesend East junctions. Added to this is the fact that they propose on a single lane linking the proposed Lower Thames Crossing to the A2 in each direction.

If the Lower Thames Crossing is to attract Channel port traffic away from the current designated freight route (M20/M25/Dartford Crossing) the alternative routes are via the A2/M2, A249, A229, A228 and A227. No proposal currently exist to upgrade these routes so it is highly questionable whether these have the capacity to deal with the additional demand. These routes clime the North Downs, steep hills that HGV’s struggle to cope with, especially in winter conditions.

This is how the signage approaching the Gravesend East junction would likely look when the Lower Thames Crossing opens.

No further significant capacity improvements are proposed to be delivered at the Dartford Crossing so it is reasonable and logical to expect conditions (congestion) to continue much as they exist today. Highways England claim that the Lower Thames Crossing will take some of the pressure away from the Dartford Crossing, but we think the amount of pent-up demand in the M25 corridor significant exceeds any such reduction so in reality the Lower Thames Crossing will make no difference whatsoever.

 If there were any doubt as to the direction from which most traffic using the Dartford Tunnels comes, consider this Google maps capture of junction 3 on the M25 of 04 October 2021. It’s quite clear very little traffic comes from the designated freight route, the M20, compared to the M25 anticlockwise, as the dedicated slip roads are shown in green whereas the M25 is shown in red depicting slow or queuing traffic. This is just one snapshot, but this has been observed on numerous occasions when traffic has queued beyond junction 3.

With the level of risk for traffic incidents to continue unabated at Dartford, but given the availability of an alternative route when the Lower Thames Crossing opens, drivers will inevitably and understandably attempt to access the alternative route, aided by their satellite navigation systems.

However, Highways England do not propose to delivery any additional means for drivers to do so. Drivers will be expected to use pre-existing routes to access the Lower Thames Crossing. For M25 anticlockwise traffic this means the A2 including the already congested junction 2, the M26 and several of the ‘A’ roads between the M20 and the A2/M2 including the A227 through Meopham, the A228 through Snodland and Cuxton, and the A229 Bluebell Hill. All these routes will struggle to cope with the additional traffic and indeed Highways England’s consultation documents show this to b the case.

The Lower Thames Crossing Association does not recognise, acknowledge, or understand the depicted reduction in traffic on the A2 eastbound past Gravesend. With the 50% reduction in capacity from the A2 on to the M2 and with only one lane available to access the Lower Thames Crossing, anyone with local knowledge and common sense can see that the A2 will queue, at peak times and possibly at other times, back past Gravesend potentially to the M25 and maybe even as far as Dartford. This will have a knock-on effect on the local road network negating any benefit Highways England claim will be provided by their proposals.

The proposed Lower Thames Crossing will not solve the traffic congestion at Dartford. It will at best move the problem east of Gravesend and at worst spread the problem to a much wider area.

It will create a TOXIC TRIANGLE of pollution for residents living with the triangle formed by the M25, A2 and the new route.



The Dartford Expressway is essentially Highways England’s “Option A14” concept further developed to an outline design to demonstrate its feasibility and benefit.

The Dartford Expressway concept has the backing of Civil Engineer Ken G Bowman MICE MIStructE. Mr Bowman promoted Option A14 in his YouTube video below in 2016. See local press article here: https://www.kentonline.co.uk/dartford/news/just-build-under-the-whole-92181/

Dartford Expressway proposes the same tunnel design as the Lower Thames Crossing, namely twin three lane tunnels. The feasibility is therefore proven as far as a desktop study can ascertain.

Dartford Expressway addresses the problems at Dartford in the right place, in the M25 corridor, thereby finally completing the M25 to full motorway standard throughout.

Dartford Expressway sinks the M25 into tunnel beneath and completely, invisibly bypassing the residential areas of Dartford and Stone.

Dartford Expressway comprises a route between new junctions; one south of junction 2 and one north of junction 30 on the M25.

Dartford Expressway solves the traffic congestion problems at the existing Dartford Crossing.

Dartford Expressway provides resilience and redundancy in the event of incidents at the existing crossing and could provide an alternative route during the refurbishment works that will inevitably be required at the Datford Tunnels.

Dartford Expressway, based on published contract award values, could be built for c.£6.6bn, £1.6bn less than the Lower Thames Crossing.

Dartford Expressway, for the most part could be built entirely off-line without any troublesome interference with the existing road network during construction. Only the creation of the new junctions at either end would have an impact.

Dartford Expressway would take a tiny amount of greenfield land compared with the Lower Thames Crossing proposal. We estimate about 100 acres being required at each junction / tunnel launch site. The remainder of the route would be underground. Whereas the Lower Thames Crossing cut a 14 mile route through prime agricultural Greenbelt land.

Dartford Expressway would finally complete the M25 to full motorway standard and leave the existing Dartford Crossing (tunnels and bridge) dedicated for use by local traffic between Dartford and Thurrock only.

Dartford Expressway would completely bypass the numerous entries and exits on the A282 at Dartford and provide the undisturbed, laminar, free-flowing traffic everyone desires.

Alternatives to Dartford Expressway

The obvious alternative to the Dartford Expressway proposal is a second bridge crossing alongside the exiting Queen Elizabeth II bridge, which has been dubbed the Prince Phillip Bridge. This could be delivered for a fraction of the Lower Thames Crossing or the Dartford Expressway for a mere c.£200m. However, any second bridge would not get around one of the root causes of the problems at Dartford, namely the numerous entries and exits, as the bridge approach ramps would have to make landfall alongside the exiting bridge. Such a bridge would provide only limited capacity benefit.

It would appear no consideration has been given by the Department for Transport to other modes of transport which could assist in alleviating congestion. Rail is by far a much more efficient means of transport for both passengers and freight.


Much has changed


There has been so much change since these proposals were first conceived.

  1. Brexit has resulted in altered freight traffic movement particularly through the Channel ports
  2. Development of the London Gateway port on the Essex coast which can take container and Ro-Ro traffic directly on to the rail and road network north of the Thames negating the need for it to traverse through Kent.
  3. Development of other freeports around the country at East Midlands Airport, Felixstowe and Harwich, Humber region, Liverpool City Region, Plymouth, Solent, and Teesside which likewise can take freight closer to its destination, keeping it off the road network.
  4. Uptake of long distance rail freight by the big supermarkets bringing goods from Spain all the way to Calais (it’s shameful that the UK does not have the equivalent of VIIA Britannia)
  5. The port expansion at Calais is now fully operational with the aspiration that it will handle shipping from many ports other than Dover, supporting the UK’s new freeports.
  6. Development of the Kent Rail Strategy
  7. “Levelling Up” and “The Northern Powerhouse” policies. The north needs the investment more than the south
  8. New flexible working patterns following the Covid-19 pandemic with people working from home reducing the number of commuter miles driven
  9. New Climate Change Targets. The carbon footprint of the construction of the Lower Thames Crossing is huge and the proposed mitigation measures to plant trees won’t take effect for decades to come.
  10. The backlash against the concept of Smart Motorways in favour of motorways with hard shoulders
  11. The economy is bouncing back with large growth figures announced in the Budget 2021. The economy doesn’t need the Lower Thames Crossing for growth.