New Lower Thames Crossing

[KeithW]

At the risk of going off on a tangent, is there no room for another higher quality crossing at Dartford? If there is the obvious solution seems to be another bridge to "complete" the M25, so there would be a bridge for each motorway carriageway and a tunnel for each local/non motorway traffic carriageway.

One problem is the Dartford approaches are horribly congested. On the northern side its constricted by the retail parks, Warehouses and the MSA while on the south its hemmed in a trench as it passes through Dartford. A second is that bridges as high as it needs to be to allow ships to pass underneath is prone to closure in bad weather.

Last but not least is that its a classic case of putting all you eggs in one basket, If a major incident such as a fuel tanker crash happens this can potentially cause prolonged closure which means the M25 and much of London grinds to a halt.

[Gav]

allowing hazardous goods to use the tunnel without escort is a step backwards, Im not keen on allowing hazardous goods through the tunnel without escort. not a good move even if the tunnel is more modern, a hazardous load of specific types will always pose a risk and if you are trapped in an incident it really isnt good.

Maybe they will have specific bans on particular goods and they will need to use the dartford crossing or go round the long way maybe. who knows but its not a good step in my opinion to had uncontrolled non restricted movement of goods through any tunnel.

[Bryn666]

allowing hazardous goods to use the tunnel without escort is a step backwards, Im not keen on allowing hazardous goods through the tunnel without escort. not a good move even if the tunnel is more modern, a hazardous load of specific types will always pose a risk and if you are trapped in an incident it really isnt good.

Maybe they will have specific bans on particular goods and they will need to use the dartford crossing or go round the long way maybe. who knows but its not a good step in my opinion to had uncontrolled non restricted movement of goods through any tunnel.

ADR categories were introduced because of explosion hazards within tunnels, E is reserved for critical sites where any explosion would be catastrophic and thus hazardous goods are banned completely (see the inner London tunnels, or older Alpine road tunnels).

Dartford is C, hence why escorts are used for tankers which are nearly always carrying ratings of D and E.

The new tunnel will presumably be designed with this in mind and is likely to be Category B on the ADR scale, with escorts for anything else.

[KeithW]

allowing hazardous goods to use the tunnel without escort is a step backwards, Im not keen on allowing hazardous goods through the tunnel without escort. not a good move even if the tunnel is more modern, a hazardous load of specific types will always pose a risk and if you are trapped in an incident it really isnt good.

Maybe they will have specific bans on particular goods and they will need to use the dartford crossing or go round the long way maybe. who knows but its not a good step in my opinion to had uncontrolled non restricted movement of goods through any tunnel.

We dont require escorts at Hatfield, Brynglas or Ramsgate Tunnel which has an A rating which means No restrictions for the transport of dangerous goods and no sign needed.

As I understand it assigning an ADR rating to a tunnel involves assessing the risk using standard risk assessment techniques which look at the following
1) Evaluation of Probability of an incident
2) Evaluation of Consequences of an incident, the major aspects that are evaluated are risks to life, financial risks and environmental risks

Now Dartford doesnt do well on any of these. The tunnels are narrow and have no refuges so incidents are more likely and one would produce a major risk to life. On the financial and environmental consequences it also is close to business, retail and residential developments and of course a major incident would close the only crossing on the eastern side of the M25. Even the approaches are bad, a tanker fire here could be catastrophic,
https://www.google.co.uk/maps/@51.44243 ... 384!8i8192

The older Blackwall and Rotherhithe tunnels are even worse.
https://www.google.co.uk/maps/@51.51055 ... 384!8i8192

The LTC will do much better on all of these providing a sterile corridor can be maintained - meaning no tin sheds

While banning 'hazardous' materials is good the reality is that most materials burning in a closed space are hazardous including food products, burning animal and vegetable fats and oils. The Mont Blanc tunnel fire started on a truck carrying flour and margarine. Plastics as found in consumer goods and furniture are really nasty releasing highly toxic gases, that is why firefighters entering a burning building use BA Units and is also what killed most of those in the Grenfell fire. A realistic hazmat rating would score HGV's supplying supermarkets as high risk.

I was involved on the risk inspection process on Dungeness B nuclear power station before it was approved by the NII. The single largest transport risk was nothing to do with nuclear fuel but was the chlorine brought by road tankers that was used for water treatment. When we looked at the nuclear fuel flasks we found they were harder to crack than a main battle tank.

[Gav]

allowing hazardous goods to use the tunnel without escort is a step backwards, Im not keen on allowing hazardous goods through the tunnel without escort. not a good move even if the tunnel is more modern, a hazardous load of specific types will always pose a risk and if you are trapped in an incident it really isnt good.

Maybe they will have specific bans on particular goods and they will need to use the dartford crossing or go round the long way maybe. who knows but its not a good step in my opinion to had uncontrolled non restricted movement of goods through any tunnel.

We dont require escorts at Hatfield, Brynglas or Ramsgate Tunnel which has an A rating which means No restrictions for the transport of dangerous goods and no sign needed.

As I understand it assigning an ADR rating to a tunnel involves assessing the risk using standard risk assessment techniques which look at the following
1) Evaluation of Probability of an incident
2) Evaluation of Consequences of an incident, the major aspects that are evaluated are risks to life, financial risks and environmental risks

Now Dartford doesnt do well on any of these. The tunnels are narrow and have no refuges so incidents are more likely and one would produce a major risk to life. On the financial and environmental consequences it also is close to business, retail and residential developments and of course a major incident would close the only crossing on the eastern side of the M25. Even the approaches are bad, a tanker fire here could be catastrophic,
https://www.google.co.uk/maps/@51.44243 ... 384!8i8192

The older Blackwall and Rotherhithe tunnels are even worse.
https://www.google.co.uk/maps/@51.51055 ... 384!8i8192

The LTC will do much better on all of these providing a sterile corridor can be maintained - meaning no tin sheds

While banning 'hazardous' materials is good the reality is that most materials burning in a closed space are hazardous including food products, burning animal and vegetable fats and oils. The Mont Blanc tunnel fire started on a truck carrying flour and margarine. Plastics as found in consumer goods and furniture are really nasty releasing highly toxic gases, that is why firefighters entering a burning building use BA Units and is also what killed most of those in the Grenfell fire. A realistic hazmat rating would score HGV's supplying supermarkets as high risk.

I was involved on the risk inspection process on Dungeness B nuclear power station before it was approved by the NII. The single largest transport risk was nothing to do with nuclear fuel but was the chlorine brought by road tankers that was used for water treatment. When we looked at the nuclear fuel flasks we found they were harder to crack than a main battle tank.

we deal with helicopter loads for storing maintenance out at navigation aids, have to do the relevant courses to ensure that were following guidelines and legislation as its covered by law, some things getting into the sea etc...or contaminating the environment.

You can say that a grocery lorry could be worse with some of the plastics and packaging, that is so but the amount of hazardous loads on the road in and around dartford linked to risk assesments and likelyhoods of incident is complicated by the area and the provision of safe refuge should it go petetong. biggest worry is any incident and the ability to try and get out away from it. it will be a busy route and what ever happens you will have traffic behind and caught up in it. just a worry.

[KeithW]

we deal with helicopter loads for storing maintenance out at navigation aids, have to do the relevant courses to ensure that were following guidelines and legislation as its covered by law, some things getting into the sea etc...or contaminating the environment.

You can say that a grocery lorry could be worse with some of the plastics and packaging, that is so but the amount of hazardous loads on the road in and around dartford linked to risk assesments and likelyhoods of incident is complicated by the area and the provision of safe refuge should it go petetong. biggest worry is any incident and the ability to try and get out away from it. it will be a busy route and what ever happens you will have traffic behind and caught up in it. just a worry.

With many groceries the packaging is the least of the problems, flour dispersed in the air is extremely flammable and in the right conditions is very explosive. We mandated flame and explosion proof electrical equipment in bakeries and flour mills, olive oil is not that easy to set on fire but burns very nicely when it gets going and many other vegetable fats are even worse which is why so many domestic fires start in deep fat fryers such as chip pans.

As I already said I agree the consequences of a major incident at Dartford are indeed high which is why it has a category C, most are if anything are worse. One big issue highlighted by the Mont Blanc tunnel fire is that with narrow tunnels vehicles trapped behind a fire can neither turn round or reverse out and those escaping on foot are likely to be overcome by fumes. This can be mitigated with modern active ventilation systems which can vent smoke safely and contain the spread of the fire but these are hard to retrofit.
https://www.mottmac.com/en-US/article/6 ... ife-safety

Tunnel Locations & Codes
Blackwall (London) – Code E
Clyde – Code D
Dartford – Code C
East India Dock Road (London) – Code E
Limehouse (London) – Code E
Mersey – Code D
Ramsgate – Code A (means no escorts, signs or hazmat restrictions)
Rotherhithe (London) – Code E
Tyne – Code D

Now Hatfield and Brynglass dont appear on that list because ADR ratings are only usually applied to tunnels that are under water. Hatfield was updated in 2011 with improved ventilation, lighting and fire suppression systems and would probably get a better score than Dartford. A simulation of a collision between a tanker and other vehicles was done after the upgrade.
https://www.newcivilengineer.com/archiv ... 3-10-2011/

With Ramsgate a safe modern tunnel to the Port was built and as a result got an A rating.

[Bryn666]

It isn't particularly underwater tunnels that are subject to ADR ratings - it's any tunnel over a defined length that could be catastrophically damaged by fire or explosion as a result of transport of dangerous materials through it.

Despite the construction of new escape shafts, fire suppression, heat detection and fire doors, and improved communications systems for emergency services, when a tunnel is 10km+ long such as Mont Blanc any explosion or fire would still likely be a major disaster hence the regulation of hazardous goods (it's still Category E) and all regular HGVs being directed through a thermal scanner to ensure there are no engine problems after the steep climb to the tunnel portals. There are now strictly enforced speed limits (70km/h) and minimum distances between vehicles (200m for HGVs, 100m for everything else). All travellers are given both a placard to hang from their mirror to remind them of the rules as well as being advised to switch radio frequencies to ATMB's channel for up to date condition reports.

The wider and more open a tunnel is the easier it is for the forces of an explosion to dissipate, as the 7 July bombings showed - the deep level lines had far worse damage to the trains as the shockwave had nowhere to go so reverberated down the tube.

I'd expect a brand new tunnel like the LTC to have heat detection, smoke detection, and every kind of modern safety apparatus to allow dangerous goods through it.

[WHBM]

As was found with the (first) Channel Tunnel train fire, it isn't classified hazardous items that are necessarily the greatest fire risk. That did as much damage as it did because the lorry on fire was carrying 30 tons of pig fat.

The issue at Dartford northbound, which I have commented on here before, is not so much the restriction as the way that it is managed. One bore fully blocked, only when it is clear is the hazardous load allowed in (I don't think they are escorted any more), and only when seen clear is it opened again. But shortly afterwards it can all happen again. I've seen it, from the queue, where it was closed off again within 5 minutes of the previous closure, for no more than a single tanker - in the middle of the evening peak. Very commonly it gets closed off again before the queue has had chance to dissipate.

[Bryn666]

As was found with the (first) Channel Tunnel train fire, it isn't classified hazardous items that are necessarily the greatest fire risk. That did as much damage as it did because the lorry on fire was carrying 30 tons of pig fat.

The issue at Dartford northbound, which I have commented on here before, is not so much the restriction as the way that it is managed. One bore fully blocked, only when it is clear is the hazardous load allowed in (I don't think they are escorted any more), and only when seen clear is it opened again. But shortly afterwards it can all happen again. I've seen it, from the queue, where it was closed off again within 5 minutes of the previous closure, for no more than a single tanker - in the middle of the evening peak. Very commonly it gets closed off again before the queue has had chance to dissipate.

The previous holding area for dangerous goods at Dartford lacked capacity to allow for convoys, so the had to get things through on a drip feed basis. The new arrangement since the removal of the toll booths is supposed to have made this much easier to manage.

[A303Chris]

The only issue I have is, a lot of freight comes via the Channel Tunnel and given the height restrictions in the existing Dartford Tunnel, will the LTC result in additional traffic on the A229 between J6 of the M20 and J3 of the M2 as this is the most direct route between the M20 and the LTC.

Neither junctions are free flow, and also on a second look this will be a more direct route from the M20 to the M25 north of the Thames then going via Swanley, so even more traffic could be attracted to the route.

Personally free flow from M2 e/b to A229 s/b and M20 w/b and the reverse will be required to accommodate this diverted traffic.

[c2R]

The only issue I have is, a lot of freight comes via the Channel Tunnel and given the height restrictions in the existing Dartford Tunnel, will the LTC result in additional traffic on the A229 between J6 of the M20 and J3 of the M2 as this is the most direct route between the M20 and the LTC.

Neither junctions are free flow, and also on a second look this will be a more direct route from the M20 to the M25 north of the Thames then going via Swanley, so even more traffic could be attracted to the route.

Personally free flow from M2 e/b to A229 s/b and M20 w/b and the reverse will be required to accommodate this diverted traffic.

I think it will make the existing A229 pretty bad; yes. Perhaps once it is apparent how bad, then we'll see proposals for a replacement route in a super-expensive tunnel to bypass it.

[KeithW]

The only issue I have is, a lot of freight comes via the Channel Tunnel and given the height restrictions in the existing Dartford Tunnel, will the LTC result in additional traffic on the A229 between J6 of the M20 and J3 of the M2 as this is the most direct route between the M20 and the LTC.

Neither junctions are free flow, and also on a second look this will be a more direct route from the M20 to the M25 north of the Thames then going via Swanley, so even more traffic could be attracted to the route.

Personally free flow from M2 e/b to A229 s/b and M20 w/b and the reverse will be required to accommodate this diverted traffic.

As I recall we already discussed this in September.

[Scratchwood]

At the risk of going off on a tangent, is there no room for another higher quality crossing at Dartford? If there is the obvious solution seems to be another bridge to "complete" the M25, so there would be a bridge for each motorway carriageway and a tunnel for each local/non motorway traffic carriageway.

One problem is the Dartford approaches are horribly congested. On the northern side its constricted by the retail parks, Warehouses and the MSA while on the south its hemmed in a trench as it passes through Dartford. A second is that bridges as high as it needs to be to allow ships to pass underneath is prone to closure in bad weather.

Last but not least is that its a classic case of putting all you eggs in one basket, If a major incident such as a fuel tanker crash happens this can potentially cause prolonged closure which means the M25 and much of London grinds to a halt.

Exactly, a major reason for the new crossing is to give a completely separate route across the Thames, as currently when there is a problem, Dartford gets swamped with traffic. The last thing the residents of East Dartford want is to encourage more traffic along the A282 anyway, air quality in that area is very poor also.

[frediculous_biggs]

The older Blackwall and Rotherhithe tunnels are even worse.
https://www.google.co.uk/maps/@51.51055 ... 384!8i8192

The LTC will do much better on all of these providing a sterile corridor can be maintained - meaning no tin sheds

And hopefully no bus stops!
https://www.google.co.uk/maps/@51.51112 ... 384!8i8192

[Gav]

Going back to hazardous loads and passage through a tunnel...

It is all very well making the tunnel fire proof and with fire extinguishing and ventilation fitted the best line of protection is always going to be the removal of the risk. and suppression assumes that the worse has happened.

I did some movment around the country with refrigerant r22 and also oxy acetelene torches and had to wait for an escort through the tunnel. such is life. alternative was to go round the M25 or through london but not allowed to go through the other tunnels.

still think that these loads should not be mixed with normal traffic, held back and run through in convoy.

[Bryn666]

Going back to hazardous loads and passage through a tunnel...

It is all very well making the tunnel fire proof and with fire extinguishing and ventilation fitted the best line of protection is always going to be the removal of the risk. and suppression assumes that the worse has happened.

I did some movment around the country with refrigerant r22 and also oxy acetelene torches and had to wait for an escort through the tunnel. such is life. alternative was to go round the M25 or through london but not allowed to go through the other tunnels.

still think that these loads should not be mixed with normal traffic, held back and run through in convoy.

If the tunnel has any ADR category, which it possibly will given the length, then this is what will be done. But the overall design of the tunnel will be to mitigate the effects of any hazard regardless in order to minimise disruption to tunnel users caused by traffic management and convoys.

[Peter Freeman]

... the LTC result in additional traffic on the A229 between J6 of the M20 and J3 of the M2 ...

As I recall we already discussed this in September.

Yes - here : viewtopic.php?f=1&t=41882&p=1145346&hilit=A229#p1145346

[jackal]

The planning application has been withdrawn based on Planning Inspectorate feedback. A revised application will be made "early in the new year".

I also found it quite remarkable that "more than £100M has been spent on ground investigations due to the chalky conditions in that part of the Thames".

https://www.newcivilengineer.com/latest ... 0-11-2020/

[booshank]

The planning application has been withdrawn based on Planning Inspectorate feedback. A revised application will be made "early in the new year".

I also found it quite remarkable that "more than £100M has been spent on ground investigations due to the chalky conditions in that part of the Thames".

https://www.newcivilengineer.com/latest ... 0-11-2020/

Are those inner hard shoulders in the artist impression of the approach to the tunnel?

[Chris5156]

Are those inner hard shoulders in the artist impression of the approach to the tunnel?

I think it's just a paved central reservation where the carriageways splay on the approach to the tunnels. The two tunnel portals will be further apart than the two carriageways would be in open air.