Blackwall Tunnel Speed Limits 2022

[B1018 A120 M11]

I admit it, I’m confused. I often went through the Blackwall Tunnel before the COVID-19 lockdowns but haven’t done it for a while, and I’m wondering if the limits have changed recently in line with TFL’s policy of giving more roads a 20mph limit. And yes, of course, I can look on-line to try to find an answer… but if you do that, while you quickly find lots of sources confirming that the Blackwall Tunnel limits are 30mph (exactly as I remember it), none of them are dated later than 2019, which means that the limit might have changed since.

I passed through southbound in the wee small hours a couple of weeks ago on my way to the Channel Tunnel, and didn’t notice any changes then — but it was dark, so I may have overlooked something. Then, yesterday, on my way back from Europe, I passed through northbound and saw a 20mph sign on the other side of the carriageway, but facing me, as I emerged from the northern tunnel portal. Looking on Google Maps, there is a recent (May 2022) Streetview capture which confirms the existence of this sign:

https://tinyurl.com/BlackwallNorth2022

It’s clearly aimed at northbound traffic, as no southbound traffic would ever see that sign in its position on the back of the concrete bridge surround, and its location also means it can’t be a sign for southbound traffic that’s somehow been accidentally turned around. But it’s a *very* odd place to put a speed limit sign.

When I got home, I wondered if there were other 20 signs I’d missed, so I got Googling and found this at the southbound portal, which I didn’t see at all on my way north:

https://tinyurl.com/BlackwallSth2022

Again, it’s only on the OTHER (southbound) side of the carriageway, but facing the northbound traffic, which is odd, given that there are several gantries on the northbound tunnel approach which carry height and lane width warnings which could be used to carry speed limit signs.

From memory, the situation in 2019 and earlier used to be like this:

SOUTHBOUND:
A 50 mph limit on the A12 southbound until the Stratford Olympic Park, then 40mph down to near the Blackwall Tunnel (just north of the A13 junction, from memory), then 30mph through the tunnel until just after the junction with the A2203, Blackwall Lane, then 50mph on the rest of the A102 and the A2 out to near the M25, where NSL resumes.

NORTHBOUND:
50mph in on the A2 and A102 until just short of where the slip road comes in from the A2203, Blackwall Lane, then 30 all the way through the tunnel until the slip road joins from the A13 north of the northbound tunnel exit, at which point the northbound D2 becomes the A12 and gets a limit of 40mph out to Stratford, where it becomes 50mph again.

Of course, I could be remembering the above incorrectly…!

On both my recent trips through the tunnel, southbound and then northbound, I was careful to do 30mph or less throughout, as I always have done in the past… but could it be that the limit is now 20mph? And if so, when did it change? I can’t think of any other explanation for that sign on the other carriageway at the northbound tunnel exit (and its accompanying average speed limit warning notice)… but it seems a pretty odd way to signpost a speed limit…?

[M4Simon]

It is years since I drove that way, and even more since I worked on the Blackwall Tunnel approach roads, so I don't have a definitive answer on this. However, the southbound tunnel routinely runs in contraflow during maintenance closures of the northbound tunnel and I imagine the 20 signs are part of the traffic management regime for that.

Simon

[B1018 A120 M11]

Thanks for your reply, Simon. There is indeed some stuff I found on-line from before 2019 about 20mph limit signs being used when the southbound bore of the tunnel was used two-way, in contraflow. However, I don't know if this info is still current in 2022. I thought I had read somewhere, probably here on SABRE sometime over the past few years, that TFL don't run Blackwall contraflows through one tunnel bore any more, and that when one tunnel is closed for maintenance weekly these days, you can only use the tunnel northbound, and southbound traffic has to find another route? I seem to recall this was the case for another one of my European trips a few years back, maybe 2016 — I was due to head south through the tunnel on a Saturday night, but Saturday night is when the routine weekly tunnel maintenance happens, and I discovered that there was no southbound route at all through the tunnel, only northbound. If I remember rightly, I ended up going through the Rotherhithe tunnel instead. I had the same issue two weeks later on a Saturday night returning from Europe, but this time, although half the Blackwall tunnel was again shut for maintenance, I was now going northbound, which is the flow that is left open, so I was able to come through OK.

The sign I only found on-line when I got home yesterday, near the southern portal of the tunnel, could certainly be used for southbound traffic on the southbound tunnel bore by being turned around — it's on a pole. But as noted in my original post, there's no way that the 20 speed limit sign near the northern tunnel portal, but on the southbound carriageway (and its accompanying 'Average Speed Check' sign underneath) could ever be used for southbound traffic flows, as the sign would be completely out of sight to southbound traffic — it's on the back of a solid concrete bridge surround. Even if you turned the sign around, it would be hidden to southbound traffic by the concrete. So it must be for northbound traffic to read and obey. The only remaining question, I guess, is if it's a leftover sign from the days when they used to have mixed north/south traffic in contraflow through the tunnel, and was used only for northbound contraflow traffic on the southbound carriageway... or if it's new, and is supposed to be obeyed by northbound traffic on the northbound carriageway, like me yesterday. But if so, that is an extremely odd place for a speed limit sign for northbound traffic when both tunnel bores are open normally, and rather confusing.

On a dual carriageway, doesn't a speed limit sign have to be on the side of the road you're travelling on to properly apply to the direction you're travelling in? Or is that just the way it's usually done, and not traffic law?

At the end of all this typing, I'm still not really sure what the current speed limit in the tunnel is, and whether it's different in the northbound bore from the southbound one...!

[WHBM]

I thought I had read somewhere, probably here on SABRE sometime over the past few years, that TFL don't run Blackwall contraflows through one tunnel bore any more, and that when one tunnel is closed for maintenance weekly these days, you can only use the tunnel northbound, and southbound traffic has to find another route?

You are correct. Quite some years ago one TfL department spent a considerable sum replacing the 2-way signalling in the newer southbound bore, as the reliability of the previous equipment had caused issues. As soon as done, another department of TfL decided that 2-way in the tunnel was unsafe and it was prohibited from then on. So when either bore is closed it's northbound only with two lanes using the opposite bore.

[Bryn666]

There must be a much more technical reason for why Blackwall doesn't have the contraflow because 1 mile to the west a much narrower and less safe tunnel runs two way traffic every day and no one bats an eyelid.

From Hansard:

"Ostensibly, the decision is said to have been made on the advice of the Metropolitan police because there had been an increasing number of near misses and there was a road safety hazard."

Sounds to me the police couldn't be bothered doing routine patrols to enforce the speed limit and crossovers and pulled out the usual British excuse for banning anything, "elf and safe tea".

[B1018 A120 M11]

Right, Bryn — and the Rotherhithe tunnel is bendier and has pavements for pedestrians in the mix as well!!! However, at least you couldn't be accused of failing to know what the speed limit is in that one... there is no shortage of utterly unmissable 20 signs all over the place. Whereas I still don't really have a scooby what the current limit is in the Blackwall, and not for want of trying to find out on-line since yesterday...! Does anyone here on SABRE have more definitive knowledge?

MattB

[Chris Bertram]

There must be a much more technical reason for why Blackwall doesn't have the contraflow because 1 mile to the west a much narrower and less safe tunnel runs two way traffic every day and no one bats an eyelid.

Rotherhithe Tunnel has 2.0m/6'6" with *and* height restrictions, so basically bikes, motorbikes, cars and small vans only, which I would think reduces the risk element. Larger vehicles will have to use either Tower Bridge or head outwards to Dartford.

[multiraider2]

I must admit to having been similarly confused. It's that sign high up above the wall as you go down that you can see northbound that does it. It doesn't normally cause a concern because at most times of the day I would love to be able to top 20mph in the tunnel. But I do tend to go to holidays in the North utilising the tunnel and getting there before 6am. I'm going to do it again very shortly. If the tunnel is free-flowing and given that there are average speed cameras I have been concerned that I was topping 20mph on average.

I just think it's a sign that shouldn't be visible to northbound users but I also think that the speed limit is actually 30mph.

[Scratchwood]

I'm pretty sure (99.999999%) that both tunnels are 30mph.

That 20 sign doesn't belong to the northbound tunnel, as after all you can see behind it "no turning right signs", which also are for northbound traffic going the wrong way. When they do work on the northbound tunnel, they usually divert northbound traffic through the southbound tunnel, and tell the southbound traffic to "go somewhere else!". I think the logic is that it's easier for the southbound traffic to divert down the A13 to Dartford, Rotherhithe or the mythical Woolwich ferry whereas there is no such option for the northbound traffic once they've reached that point.

As an aside it's crazy that both tunnels have the same speed limit. 40 is perfectly safe southbound, whereas 30 is only attainable in short bursts going northbound. 20 north and 40 south would be more realistic.

[M4Simon]

I thought I had read somewhere, probably here on SABRE sometime over the past few years, that TFL don't run Blackwall contraflows through one tunnel bore any more, and that when one tunnel is closed for maintenance weekly these days, you can only use the tunnel northbound, and southbound traffic has to find another route?

You are correct. Quite some years ago one TfL department spent a considerable sum replacing the 2-way signalling in the newer southbound bore, as the reliability of the previous equipment had caused issues. As soon as done, another department of TfL decided that 2-way in the tunnel was unsafe and it was prohibited from then on. So when either bore is closed it's northbound only with two lanes using the opposite bore.

Not quite true. When I worked that patch, TfL ran tidal flow northbound traffic through the southbound bore for 15-20 minutes at a time, perhaps three or four times in each morning peak period, removing tidal flow when the gaps in the northbound flow became too long. They refurbished the tidal flow signals in around 2005, but as the project was finishing, it was the police who pulled the plug on tidal flow, not TfL. The tidal flow was deemed unsafe because whenever gaps in the northbound flow became too large, some southbound drivers would forget that tidal flow was operating and try to overtake using the tidal flow lane, and yes, ignoring the big red crosses above it.

The maintenance contraflow is a different thing, and as far as I knew that still happens, though it wouldn't surprise me if they'd been pulled as well.

I've posted on this subject before, and it may well be my posts that B1018 A120 M11 is referring to.

Simon

[M4Simon]

Sounds to me the police couldn't be bothered doing routine patrols to enforce the speed limit and crossovers and pulled out the usual British excuse for banning anything, "elf and safe tea".

The police were all over the tunnel and its processes - I have been in the control room and have seen the problem with my own eyes. However, they do not have the resources to have endless patrols running back and forth to catch a driver who attempts an illegal overtake inside the tunnel.

Simon

[Telstarbox]

I've been through northbound at 30mph before (at off-peak times) and always wondered if that stray sign was a mistake. Never had anything through the post so assume the enforcement is set up for 30 not 20.

As an aside that bus stop in the cutting for the 108 must be the bleakest one in London!

[B1018 A120 M11]

Well, that's reassuring — thanks everyone. If most people who've posted here think the limit is 30 (as I did), have been through the tunnel on that assumption (as I did) and *not* received a penalty in the post, hopefully it will go the same way for me.

As a final thought on this, it does amaze me that in this day and age, it can be so hard to find out the speed limit on a certain piece of road, and that even with publicly accessible resources like Google's StreetView, the situation can *still* be so ambiguous thanks to confusing signage. I'm clearly not the only one who has wondered about the limit in the tunnel, and not only amongst those who've replied in this thread here on SABRE, but also more generally on-line. I found out from Googling yesterday before posting here that someone actually went to the extent of using an official Freedom of Information request in 2019 to find out the tunnel's speed limit, which shows the lengths you might have to go to to get a definitive answer! The official answer given then, incidentally, was that the limit was indeed 30... but as I said in my original post, that was in 2019, and I was concerned the limit might have changed *since* then, particularly as a spate of limit-lowering happened on fairly big roads like the A10 on TfL's watch earlier this year.

[WHBM]

Given that we live almost within sight of the north side ventilation shafts, and during school hols I'm currently doing a round trip through then back quite often, and paid particular attention this morning, I can give a bit of a commentary.

The southbound is Variable Speed, as indicated here

https://www.google.com/maps/@51.5112786 ... 384!8i8192

there are switchable louvre signs, and LED lit signs inside the tunnel. Must say I have never seen them show anything other than 30. The variable speed was presumably put in when the two-way contraflow signalling was all renewed, maybe 10 years ago.

The southbound, newer bore, has fixed signs at the southern end facing diverted northbound traffic for that bore showing 20, so presumably the LED signs show that when reverse running is in force. As described previously, two-way traffic within this bore was fully banned some years ago. TfL ? Met Police ? It's all under the Mayor of London, just different departments.

Northbound, old bore (waiting for someone to say like me), I looked this morning and there is not a single speed limit sign I could see after the 30 well back up the approach, so presumably that applies at all times. It's pretty self-enforcing. There are 10mph MINIMUM speeds on both bores, so if 20 is in force that's a pretty narrow band you have to be between (is there any narrower anywhere else ?)

https://www.google.com/maps/@51.51246,- ... 384!8i8192

[M4Simon]

Northbound, old bore (waiting for someone to say like me),

I'll bite...like you

I looked this morning and there is not a single speed limit sign I could see after the 30 well back up the approach, so presumably that applies at all times. It's pretty self-enforcing. There are 10mph MINIMUM speeds on both bores, so if 20 is in force that's a pretty narrow band you have to be between (is there any narrower anywhere else ?)

I assume there are no 30 repeaters as the Blackwall Tunnel is lit by a system of street lighting with units less than the presecribed distance apart, so the national speed limit for such a road applies - 30mph. As you say, it is self-enforcing.

Simon

[Telstarbox]

I've just found a couple more 20 signs which are on the rear of the gantry on the southbound carriageway (just north of the control room?). In that position I can't see how they could be expected to apply to the northbound carriageway, so that would support the 'northbound but contraflow' theory.

https://www.google.com/maps/@51.5096105 ... 384!8i8192