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It's a really cool idea, but I couldn't help but think they should move the water stop sign to well BEFORE the million dollar damage point. Some big trucks would have a hard time seeing the stop sign, reacting to it, slamming on the brakes, and coming to a complete stop in time before they cause damage to the overhang and beams.
The advantage with the signs before the final water sign is that they should be enough for any reasonably alert driver and don't make the environment more hazardous.

You really want to have the water screen projection, which douses the road with water, as the last line of defence. Water on the road is likely to make it far more difficult to stop a large truck like that. Having it earlier could actually be detrimental to their stopping ability[1].

We're also assuming the unexpected water doesn't cause additional accidents from all the other vehicles. A wall of water could provoke some quite irrational reactions. I drive that road on a fairly common basis and even a small accident there could well result in an expensive pile-up.

[1]: Conjecture

Better a wall of water than a truck crashing into the tunnel!
I worked near a train bridge that was constantly being hit by trucks. It was a near weekly event at times. They installed big, flashing lights and drivers would still blow through.
Check out 11foot8's YouTube channel for some great examples of how common this can be in some places.

http://www.youtube.com/yovo68 http://11foot8.com/

An other fun one is "2m40" (after the tunnel's height, of 7ft10), on the tunnel de l'etoile in Paris: http://www.2m40.com/ (in 2009, a truck crashed into it every 10 days and there were bets on the time the hanging sign would last)
signs and "plackards" go ignored all the time. i worked in a computer lab and had to put up signs when things were broken ( internet, printer, etc.. ) and we always got people ignoring them...
"Placards" is the word you're looking for.

Yeah, nobody likes reading, and even when they do, they assume that they can disregard the signs if they have a good reason - such as, they reaaaally want to.

At some point you have to accept this, do some A/B testing and find the way to actually get people's attention. For instance, a WET PAINT sign will be ignored. But "This paint was wet at 8:32 AM, please do not touch til after noon" might be more effective.

A sign on the printer that just says it's broken will be blithely ignored. But if you cover it with a sheet, and the sign says "Printer out of order on May 10th, tech has been notified", that's a lot tougher to miss.

The burden of communication is on the communicator, not the recipient, so if the sign's not working, get better at making signs.

Sort of related: I heard a story where a decorator would write signs that said "wet pant" instead of "wet paint", because the "wet paint" sign would cause people to touch the paint to see if it was indeed wet. The "wet pant" signs, however, would cause people to point out the spelling error instead of leaving finger marks.
True, but not always. There will always be the 1-3% of the population that can't do something right, no matter how elegant the UI or detailed the sign. These trucks fall into that bin. Some people are just going to plow through whatever you put in their path.
I have to agree.. thanks for the reply I guess i never thought of that while i worked there, i just kept thinking "why don't they read the signs...", we did try a few different ones, and also made them 2 feet from the door sometimes, but it was still ultimately our responsibility to inform them of whatever the situation was..

@placards: i figured i spelled that wrong, thanks

No. The whole point is to make this work for the sleep-deprived, inattentive drivers. Designing for "any reasonably alert driver" will result in horrible accidents.
When we have reliable, safe, self-driving cars this is the first industry that should be replaced by robots. How archaic is it that we pay people to ruin their bodies while attempting the inhuman task of keeping perfectly alert for several boring hours, while piloting a giant mass at lethal speeds.
Unfortunately when we have reliable, safe, self-driving cars, the loudest complainers will be truck drivers who now have to find new careers. I hope I don't sound too mean to hope their concerns are ignored.
I predict legislation saying that certain self-driving vehicles cannot be unmanned. This benefits the truck driver while still maintaining a reason to have one. Besides, someone will still have to fill the thing with diesel.

In the long term, though, you're most likely right; truck drivers will have to find new careers. However, said legislation combined with what I believe will be slow adoption due to high cost should give truck drivers a decade or two to migrate to other jobs.

Someone can fill the thing with diesel at the gas station. You'll get full-service pumps outside of Oregon and New Jersey! (Another industry that requires regulation to avoid firing unnecessary people).
Over that long, most of the industry should disappear through attrition alone.
If we make long-haul trucks self-driving, then we'll just have to replace the 'driver' job with 'guard' job. Otherwise it's far too simple - block the road; the robot will stop to avoid an accident, and you loot the cargo and/or the car.

It doesn't really matter what they're shipping - a truckload of TVs is nice, but even a truckload of sh*t is valuable enough to make it worthwhile.

That's fine as long as they don't kill people by driving while fatigued
It's a really cool idea, but I couldn't help but think they should move the water stop sign to well BEFORE the million dollar damage point

I thought the stop sign was only visible because of the dark background (i.e. moderately lit tunnel) behind it?

My first thought was similar - it needs to be seen sooner - but I presume that even some braking before slamming into concrete is better than none.

You mean, before the 3 flashing stop signs BEFORE he got to that point?

A better idea might be a low bar that causes the truck damage well before they reach the tunnel. Only issue is how to make it safe and very obvious it's done the truck damage?

The problem with a barrier that is hit is that you need to make sure it is structurally sound before you allow any other traffic past it. And if it leaves debris on the road, that needs to be cleaned up too. It's already a slow process to back out the oversized truck, so you don't want countermeasures that make it even slower.
I wonder if a clearly labeled "all trucks go into this lane" well before the tunnel would work. You could have your barrier there, and not impede the rest of the traffic. You could even divert trucks into the car lanes while you clean up.

One one hand, they're already ignoring signs. On the other hand, a sign that says "ALL TRUCKS go this way" might get a better, or at least different, response from "YOU are too tall".

Depending on the truck, load, and barrier, that could be a hazard to other vehicles and occupants. Likely less so than the tunnel itself.
Many places in Europe have a bar with chains, the chains hang off the bar at the height of the upcoming tunnel / bridge. Does of course assume that the driver will hear the chains knocking about on his truck...
The whole point of the water sign is not to cause damage/kill regular cars that might be next to or in front of the truck.
You mean, before the 3 flashing stop signs BEFORE he got to that point?

The video shows why the stop-signs may be ineffective:

https://www.youtube.com/watch?feature=player_embedded&v=...

They use the blinking not only for critical messages ("STOP") but also for unimportant stuff ("slow down"). The boy who cried wolf...

I think they actually shut down the lights in the tunnel before the screen goes off. You can see it in the video when the lights go off and tunnel is suddenly much darker.
Probably not the whole tunnel, just the entrance to enhance the projection effect. Remember there is still traffic in the remainder of the tunnel.
That and apparently some active enforcement about load heights. Load height is one of the things that is checked and enforced at truck inspection stops on US highways and interstates for this exact reason (to try to prevent over tall loads from damaging bridges).
We have a variant of this installed on a tunnel (which is probably safer, but not as cool :) ): Directly after the last highway exit before reaching the tunnel is a light barrier installed. If something breaks the barrier the tunnel entrance will be closed by boom barriers (and warning lights, so nobody drives into the boom barriers). Then the police drives out to the tunnel, finds the culprit, pulls him out and unlocks the tunnel again.

Obviously, this only works because there is enough time after the last exit to block the tunnel before the truck reaches it.

There are already THREE HUGE flashing stop signs that light up on the way to the tunnel if your truck is too big. The water sign is a last resort only.
ironically, the water on the road makes it that much more difficult to stop
The sign was mounted just inside the tunnel. If the truck were there, then it's already too late.
ironically, physics would preclude an oversized truck from reaching the wet pavement.
It has carefully designed overhead friction surfaces?
I daresay you could engineer a drainage grate or something beneath the sign jets to minimise the problem.
The footage of the 20 ton beam getting knocked out of the tunnel ceiling by a truck was remarkable. I hope there were no injuries!
I'm surprised a truck was able to knock it down. A 20 ton beam sounds like something that's rather important, I figured it would be attached fairly securely.
Well if the common use-case is for force to come from the top, they probably didn't optimize for the case of lots of force coming from the side.
What a neat idea! But if these trucks are PURPOSEFULLY breaking the laws and continuing to go through the tunnel, I am not sure that this solution will hold up for too long; after all, the clever truck drivers will know it is a mere illusion.

Furthermore, instead of a water screen, wouldn't a brick screen be more effective? Personally, I wouldn't mind going through water nearly as much as I would be running into a brick wall. Nonetheless, as I said before, a really neat idea and definitely a solution for some instances--limitations need to be addressed though.

Funny, I also thought a stop sign wasn't severe enough (I wanted the water screen to project an oncoming semi to scare the sh*t out of the driver), but illusions like that would cause some drivers to panic and endanger motorists around them.
"would cause some drivers to panic and endanger motorists around them."

About to smash out the top of a tunnel and crush the neighboring cars under your rubble? If you're not already in a panic, its certainly time to start...

I don't think the water is used to make the driver think he's about to drive into a wall of water: I figured the water is used as a medium for projecting the huge stop sign in front of them?
Err, they're not going through the tunnel. They're too tall for it. They crash into the roof of the tunnel, causing severe damage to the infrastructure, their trucks and anyone who happens to pass by.
There's likely some space left between actual tunnel height and truck height limitation (for safety), and clever driver's incentive to go through the tunnel (if it's a nice shortcut) might be stronger than any kind of sign.
Can you, maybe, also cite a trustworthy source on how many trucks actually went through the tunnel without a problem? I imagine there're clever drivers who know precisely metrics of their vehicle and tunnel regulations. I think we rarely hear about those cases on the news, though.

Edit: if you're responding “No” to whether there's leeway between actual tunnel height and regulations, I'd like to hear a source on that as well—I couldn't find one, but common sense suggests that in such a case then there'd be enough incidents of trucks with allowed height damaged because of, say, a bump on the road.

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I think you missed the point, and most of the video. If the truck continued it would have crashed into the tunnel, tearing off the top of the truck and possibly taking days to clean up and fix. The video showed one of those accidents.

I don't think ignoring the illusion and trying to continue would do him any good.

The drivers aren't doing it purposely. They have been driving for 16 hours, are in an unfamiliar city, and are almost asleep at the wheel.
16 hours!? Wow. The EU has a legal maximum of 10 hours per day — and that's only allowed twice a week, ordinarily 9 hours, with at least 45 minutes break every 45 minutes.
And the trucks are controlled, still drivers manage to trick the regulators: "I'll drive your shift now you'll get mine once" etc.
If you deliberately put yourself in a situation where you're operating a machine without the mental faculties you need to do it safely, then I think we can safely say that you deliberately caused the accident, even though you may not have thought, in so many words, "I think I'll go cause an accident now."
People are probably more afraid of losing their jobs. They also probably think it won't happen to them.
I doubt the driver was scared of losing his job. I would say that the blame may fall, in part, on the company. I have a friend who owns a business which does a lot of trucking. If they work overtime, these drivers can make $70k+ a year (including benefits, health). For a job with few qualifications needed, that's pretty good. A lot of businesses in the area actually have too few truckers.

Anyway, the point is that by working overtime you can make a good living being a driver. This is why you can find so many truck drivers drivin tired. As such, there are strict rules in place at my friend's business that prevent drivers from driving for too many hours / too many hours without a break. With GPS and whatnot, this is quite easy to monitor and enforce. As a result, along with other rules and superb maintenance, my friend's business has a superb safety record. There is still the occasional accident (can't stop 'em all), but something like this incident has never occurred.

Well, if people are deliberately endagering lives of others for fear of losing their jobs; then maybe we should ensure that they'll fear the legal consequences more than their boss?

For example, if you temporarily take away the truck drivers licence as a punishment for driving too many hours without rest (as EU does, for example), then they'll make sure that they don't drive without rest, since they will definitely lose their driving jobs if they do.

low-tech solution: http://vanishingpoint.at/wordpress/wp-content/uploads/2010/1...

(edit: actual image url instead of article)

If you hit that sign chances are you'll rip it down and drop it on the car behind you, as can be seen happening in the video in the linked article.
A fairly low bridge (high enough for a standard trailer, but any oversized loads on a flatbed could easily hit it) in my area had what were essentially large metal cans hanging by wires along a sign warning about the height. Anything tall enough to hit the bridge would hit the bits hanging from the sign and clang them around/together/against the vehicle which makes a pretty audible noise for the driver.
More severe low-tech solution: https://maps.google.co.uk/maps?q=blackwall+tunnel&hl=en&...

(Blackwall Tunnel, northbound, London)

And again, just in case you missed the scraping sounds the first time: https://maps.google.co.uk/maps?q=blackwall+tunnel&hl=en&...

(For some reason they don't appear to have anything similar going south...)

There is a diversionary slip road for overheights (OHT) on the approach to Blackwall after the first pic and before the second. If you've made it to the second (having ignored a good few red lights), expect to be prosecuted.
It was cool seeing it in action (I wonder who thought of it, and got passed the bureaucracy to make it happen). I wonder whether they considered industry standard truck height when building that tunnel.
Overheight vehicles are 4.3m and over in New South Wales, and this tunnel is signposted at 4.4m (and probably has a bit of leeway).

Trucker often have to deal with road limits: they are expected to know the size of their vehicle and pick an appropriate route. And if they don't, they are expected to read the signs along the route that indicate road limits ahead.

If anyone was at the London 2012 Olympics then they may have seen this: http://www.youtube.com/watch?v=FwNTczEIaDI

They may well have these in many other places of course, I thought it was dead cool.

When I'm rich I'm going to build an RSS reader that works like this
Cool enough that some exec is wondering how they can utilize it for future advertising. Looks like that water screen even had space in the corner for a "Glasses not working? 1-800-CONTACTS".
Sydney's harbour tunnel was built to relieve congestion on the famous Sydney Harbour Bridge, and both the bridge and tunnel follow very similar paths.

This tunnel doesn't need to accommodate every vehicle size as there's a perfectly serviceable bridge right above you.

What if it was a convertible truck??
It'll end up convertible if it wasn't before.

Crashing into a bridge like that can peel the top off like it was hit with a can-opener.

Nice blog spam. A youtube video with no article.
You might think that trucks ignoring multiple, obvious flashing warning signs wouldn't be that common. This hilarious video proves otherwise:

http://gizmodo.com/5955244/watch-this-bridge-destroying-doze...

"multiple, obvious flashing warning signs wouldn't be that common."

Unfortunately they are way too common. Did you know there's wild animals living outdoors and they cross roads? 75 miles away a divorced family is having a custody dispute so here's abduction alert #243 for the year as a punishment from one parent to the other? There's a terrorist hiding behind every tree stump? Next month some roadwork is planned although nothing so far has been done other than put up the warning sign and barrels and collect higher traffic ticket fees? Six months ago a long term road work lane closure happened so everyday commuters now completely ignore a giant bright flashing warning that lanes have changed? The bright flashing overhead sign reports that 30 miles away where you aren't even going, there is a traffic jam? This is before I even get started on the billboard advertisements designed to distract you from driving.

If everything's an emergency, then nothing is an emergency. Including, unfortunately, bridge height.

These yellow flashing signs are useless, as you say, but you'd think that drivers are conditioned to obey traffic lights, and most every tunnel in existence - including the one in Sydney - has these red and green lights up top that allows the tunnel crew to block lanes individually. I couldn't tell why truckers see these and still blow through them.
Precisely right. Overabundance of signage only conditions drivers to ignore individual signs.
It's easy to not see stuff when you've been driving for 16 hours straight.
It's also easy to not see stuff when you're blind drunk.

Both of these things are illegal, it's no excuse.

Not sure about Sydney, but there's no international law stating that you can't drive for 16 hours straight.
I was under the impression that all civilized countries do have such laws - the impact on accidents and fatalities is really huge.

Throughout almost all of Europe cargo haul & bus drivers hours are regulated (registrating devices at the vehicle + enforcement by traffic cops), and you can't take a truck across the continent w/o rest unless you swap drivers.

It's not about excuses. It's about avoiding that the accident happens, because it can cause the tunnel to get shut down for weeks.
If you can't read or don't speak english, a sign with text and flashing yellow lights may not be that obvious.
Then you didn't pass your driving exam and get a license. In the US that's required and I suspect most countries require the ability to understand posted signs to get a drivers license.

If you're driving without a license, then that's a different issue.

You might be driving abroad on a valid license, just not a license from the country you're driving in. In which case it's perfectly possible the signs wouldn't be in your native language.
The video that jere linked to is from North Carolina which happens to be where I live. The drivers test here is offered in English, Spanish, Chinese, Japanese, and Korean. They also offer it orally, specifically for people who have trouble reading. There's a sign test, but they just show you the shape and color of a sign without text. For example, you have to identify that a red octagon is a stop sign and a yellow pentagon indicates a school zone. At no point is your ability to read english tested so it's perfectly plausible that someone could obtain an NC drivers license and not understand a yellow flashing sign with text on it.
Touche. I worked at BrightLeaf Sq next to this bridge for a few years. While the wording might be different across languages, all the aforementioned nations use Arabic numerals to my knowledge, so "11.7ft" would mean the same to them, I'd hope.
They could get more creative and put up a projection of Steve Irwin with crocodile in hand, going "Crikey. An oversized vehicle. Watch out boys and girls - DANGER! DANGER!!".
Why not have a plastic flap hang down and thwack the top of the too-tall truck?

Next, if that's ignored, a plywood barricade hanging down: Better some splintered plywood than a jammed tunnel.

And lastly a large flashing sign, or water sign, saying there is tire damage up ahead. Then have tire damage spikes come out of the road. It's the drivers responsibility to not damage the tunnel or bridge. Better to damage some cheap tires on a truck than the tunnel.
That's not a good idea. Tire damage reduces control of a multi-ton vehicle in the middle of traffic, and vastly increases the amount of time it will take to get the vehicle back out. Even the flying rubber tire parts have huge amounts of energy and can damage nearby cars or even kill people.
The trick then is to have something negative happen before the tunnel that isn't so dangerous to other drivers.
A vehicle with its tires blown will take longer to stop than one with its tires intact and brakes applied. This would just turn it into an 40-ton wrecking ball - what if there's stopped traffic in the tunnel?
Yeah about that, giving some severe tire damage to a truck isn't the best way to bring it to a safe halt.
Because nothing communicates "STOP" better than A GIANT F'ING RED GLOWING STOP SIGN AS BIG AS YOUR TRUCK RIGHT IN FRONT OF YOUR FACE. ('shouting' to convey the brain-slamming scale of the message it communicates, not yelling at you.)
It can't hang down lower than the height limit. Trucks that are over by just a few inches will not even feel the hit, as seen in the other videos posted here.
How is this HN content?
And I think some people will STILL crash on the tunnel anyway.

I made a arcade game once: www.abril.com.br/blog/campus-party/2011/01/19/fanatico-por-jogos-leva-seu-proprio-fliperama-para-a-arena/

It has instructions printed on the sides of the screen... It was VERY, VERY, VERY common to someone ask people around them what a button do (sometimes to even random passerby people, or for example a couple arrived at the machine, and the guy would start to play and ask stuff to his girlfriend), and then the asked either looked confused, or pointed to the instructions, and the people asking would behave surprised, confused and shamed.

Why people ignored the instructions and asked for example their girlfriends, random people and so on instead?

Why people see a huge sign blocking the way to a ATM saying it is out of order, they remove the sign from the way and attempt to use it anyway?

Or alert boxes: Don't assume people read them. Most don't. They just click them away. Even if given several choices.
its because most instructions are unhelpful and a waste time to read, so we're conditioned to ignore them.
Even when you make great, easy to understand documetation, people are fucking lazy. That fact keeps the most of people in our support department employed.
I don't think you read the parent comment.
An important customer once told me "Yes, I have read about the manual, but it is so much easier to call you." - the problem with lazy customers is that they will make false assumptions about what the software does (everyone will probably do this at one time, but not reading the manual / instructions is much more dangerous).

She also refused to upgrade from a 15" monitor to a larger model, so we had to keep the screen layout in accordance with her outdated screen format. (The cost of a new screen would have been negligible compared to the profits).

That's probably true, I'm always surprised when I find the answer to a problem is in the manual.
From their perspective, they can't really know whether the sign is accurate or out of date.

When you get somewhere and ask "Is this the address X?", it's not because you have absolutely no idea where you are, but rather because you're only 97% sure and hence would like a simple "yep" confirmation to reassure yourself.

Designers are often burdened with creating a design that doesn't require additional interaction by the user. To create something where the user needs to consult instructions or a help file often deters new users from getting past the initial discovery stage.

Even then though there are those "special" users who are beyond help and ignore all rational signs and hints along their path to self destruction. My first job was pumping gas and we had one set of pumps that had a smaller tank than others: it ran out very quickly. So when it was empty we'd put "Out of order" bags over the pump (clearly displayed and labelled) only for people to drive up, remove the bag then complain the pump is dysfunctional.

You should talk to my mum about it. When anything comes up on her computers' screen, she will just panic and call me or my dad or anyone else, BEFORE even reading what is says. Most conversations look like this: "Hi son, my computer just broke, something came up on the screen and it won't go away" "ok mom, what does it say?" "I don't know, I haven't read it"

People are exceedingly good at ignoring information if they don't want to get involved....

So damned true. In one of my apps, I literally had to hide everything else on the screen to keep people focused on the tasks at hand, one field at a time.
This is a very innovative idea. I have seen those water displays shown in the malls for fun. This is a very cool application of a fun technique to save lives and property damages.
I'm mildly surprised that requiring trucks to file travel plans has not become a more widespread practice. What with terrorism concerns, and the widespread use of GPS monitors on trucks it's both feasible and plausible. It seems like major metro areas could institute a slightly tighter control of large load vehicles; which could actually benefit from coordinating with traffic control signals in some cases.
I'm also surprised that the drivers or their company failed to check a truck atlas when planning the route. I imagine the company has just as much incentive to prevent incidents.
Did you notice the truck in the video was overloaded way above the normal height of the bed? The truck could have easily passed any checks on paper, but the load itself is what causes the interference.
Yeah, in theory they would check the heights in the atlas versus the effective height of a given load, not just the height on paper. Why the truck was overloaded also begs a look at company policies. If this particular site is experiencing this issue 2 or 3 times a month then I wonder if the cost of guessing wrong and congesting the tunnel isn't high enough compared to just sending two trucks.
Since Garmins and other GPS devices have lane information and speed limit information, you'd think you could punch in your load height and get a route that worked for it.

Anyone want to go collect 500K bridge heights for the database?

In the US at least the state DOT's have that information and have a GIS office that would make it available for a nominal fee. You'd still need to check a lot it in cities. Big worry would probably be liability; if your database of overpasses has an error (inevitable) can the truckers insurance company hold you financially responsible for relying on your app?
Garmin already offers a specific product line for truckers and bus drivers, that deals with these kinds of issues - beyond vertical clearance you have issues of turning radius and maximum load.

I've seen them being sold at major truck stops in the US. You're not suppose to use a normal consumer GPS if you're driving an oversize / multi-axle vehicle.

http://sites.garmin.com/dezl/

That's a cute high-tech solution. A simpler one is to put a horizontal bar, the same height as the tunnel's ceiling, which will physically stop the truck before causing millions worth of damages. It's often done in France, sometimes with an early warning: a first arch with chains hanging to the maximal height. It makes a lot of noise on the truck's top, but won't destroy it.
A similar solution is used in my area yet perplexingly it still doesn't seem to stop it happening... so I think new ideas like this are definitely a good thing.
Did you see the truck in the video take out an enormous steel beam that was presumably attached to the structure of the tunnel in some kind of permanent way? How would your solution avoid the same fate?
The warning beam is several stopping-distances before the tunnel itself, and far easier to replace/reconstruct.

I'd try a 3-stage contact-warning system:

(1) hanging bar that makes noise on contact but causes little damage. This might even go before a suitable turn-off.

(2) breakaway cord with trailing noisemakers. This would be torn from its mast by the collision, and drag noisy items behind, emphasizing the need to stop and investigate.

(3) hard bar providing some slowing/resistance (but almost certainly not full stopping power, given the position and expense). By design this would actually damage the vehicle (and even risk harming the driver), approaching the same level of damage that would occur at functional tunnel-entry. But, it'd happen earlier where easier to clear/repair.

And yet, with this solution, no repair is needed for either the truck or the infrastructure.

The vehicle is able to be removed under its own power, the driver is not injured, there is no debris.

If you are in a vehicle behind a truck that has damage to its top, you very likely will have damage to your vehicle from flying debris.

Or a ten-ton beam falling on your car.
Oh, I like the water-wall too. But a driver who misses the 1st two no-damage physical-contact warnings I've proposed -- and thus would hit the damaging third hard bar -- would quite possibly ignore the water-wall too.

After all, the water wall seems primarily visual, and the driver has already missed numerous visual warnings. The contact protectors add collision-noise and vibration, which are rare enough that even a dozing/road-hypnotized driver is likely to take note.

Comparative testing is of course justified.

Solid beam is probably a bad idea, but many tunnels have chains dangling above the road at the tunnel's maximum height - if you hit them, you will hear it,but they will do little damage to the vehicle.
Solid beam is an excellent idea as last recourse, from a structural POV since the vehicle is going to be destroyed anyway it's better to destroy it before it damages the tunnel itself.
That beam they took out is called a "sacrificial beam." It was not a structural support, but was meant to take the impact before any structural members were damaged. You'll see them on many modern bridges and underpasses.
That's interesting and seems like a good idea, except perhaps it should be paramount that the 20-ton beam NOT fall on the following cars! That is an entirely different meaning of "sacrificial"...
See the videos on 11foot8.com, that beam is a freestanding structure separate from the bridge solely designed to decapitate trucks.
The sacrificial beam that appeared to fall on top of the car behind the truck?
Something that causes the vehicles engine to stop... a shock? It wouldn't stop the vehicle but it will decrease destructive force.

Or a trapdoor (warning this is a joke disregard it if you know you don't like jokes)

(intentionally ignoring joke warning…)

Excellent plan! A trapdoor! In the harbour tunnel!

Relevant anecdote: My Dad worked for the company who built the fire control system in the Sydney Harbour Tunnel. It's got (from fuzzy memory - numbers not guaranteed accurate) 128 sectors of "deluge valves". It's got pumps capable of keeping up with only 10 of those sectors of deluge valves - more than 10 sectors of valves open means even with all pumps running at maximum capacity the tunnel will fill up with water. There's some software controlling it all which is intended to ensure the operators don't accidentally flood the tunnel. Dad knows who wrote that software - he won't drive through the tunnel.

Yes, I hope though that the pressure on the writer of that software was enough to make him check thoroughly for errors.
I guess they are afraid that the broken bar can damage some other vehicle. Still, something heavier that can be damaged and can stop the truck before the tunnel is the proper solution, not the strange projections. Drivers are too sleepy sometimes, in spite of the expectations of the idealists.
One additional benefit to the water sign: It doesn't leave the roadway strewn with debris.
self-driving car systems are going to eliminate human operators in a few years anyway, no?
In a few decades maybe, certainly not a few years.
The Blackwall Tunnel in London has a something similar with heavy metal weights on chains. http://www.sabre-roads.org.uk/forum/viewtopic.php?f=1&t=...

These will make a fair mess of a vehicle, I saw them hitting a lorry once but are pretty attention grabbing.

The Blackwall Tunnel has different heights and widths for different lanes due to the tunnel profile which is why the restrictions are different in each lane in this photo.

In some jurisdictions, the owner of the truck can sue you for damages if the structure was constructed with the intent and purpose of damaging the truck.
Sad, when the alternative is no device there, and the owner of the tunnel/bridge can sue the truck owner for damages.
You just need to remember that a small number of people are just not going to get it. Mostly truck drivers that are dead tired. That water screen does the trick because you're not expecting it. Signs, bumps, and noises are all common to highway driving.

In Boston a few months ago a coach bus had the top ripped off going under a 10ft bridge on a road that truck/bus traffic is banned from. The driver hit several low bars and signs and plowed onward until the bridge cut the top off. Several times a year this happens on Storrow Drive, despite all the warning devices as some drivers just can't be reached.

http://bostonherald.com/news_opinion/local_coverage/2013/02/...

we had a fatal bus crash at the Miami airport back in december due to the driver not heeding the signs .

http://www.miamiherald.com/2012/12/04/3126826/details-emerge...

"When Miami-Dade Fire Rescue arrived five minutes and 10 seconds after the first emergency call, they began to pull passengers out of the window. Lopez, now out of gauze, told rescue workers that the victims were all Jehovah’s Witnesses, and couldn’t receive blood transfusions because of their faith."

Sigh.

"Mostly truck drivers that are dead tired."

This. People don't even realize how important it is that people operating heavy machinery are well rested, and sometimes even put down appropriate regulations as just "worker's issues". Then you get a sleepy, bored guy on a highway, with neither awareness to spot dangerous situations, or willpower left to restrain from doing stupid things. It's a testament to how good they are at their jobs that they get to their destinations at all.

And that's why the EU every truck needs to be legally fitted with a Tachometer that measures every parameter of a vehicle, and a truck driver cannot legally drive for more than 8 hours (I think they can do 9 hours once per week, and they need a 24h break at least once per week as well) - after that, they need at least 8 hour break, when the vehicle cannot move. If the truck is stopped by the police,and they find that the driver has been driving over the time limit in the past 3 months, they will issue a massive, multi-thousand euro fine, so it's extremely rare for drivers to work overtime.

I knew a driver who drove for loading at a company, and because it was taking them too long, his time for a break started before they finished. He refused to move the truck from the spot for a whole 8 hours,even though it was blocking the warehouse - he knew that if he moved it even a little bit, he(and the company he worked for) could be fined several thousand euros months down the line.

Actually I'm from EU country(-ie, actually), and it works... inconsistently. There's fraud, and there's shifting the blame on drivers while trying pressuring them to take the risks anyway (works especially 'well' in countries where many truck drivers are self-employed, like, say, Poland).

And then you get a Polish bus driver with a bus full of people going for a pilgrimage through Swiss Alps, which then fills the news for a week in two countries.

It's way better than nothing, though, and the deficiencies are something that should be fixed even within existing law (e.g. the "self-employment" could really easily be proved to be actually a normal job, if the prosecution cared enough).

These restrictions exist in Australia as well. They sometimes need to refund the drivers if they get fined due to a traffic lockup.
That's the beauty of the metal bar 10m before the tunnel: they won't fail to notice when it acts as a can opener on their truck's cabin, and it only costs a metal bar in public infrastructure (plus towing a cabriolet truck out of the way)
Violently ripping off the top of the actual cabin at speed sound like a way to have a good go at killing the driver.
They showed footage where low bars did physically stop the truck (or at least tore off the top part of the cargo container), but this still caused debris to be showered across the tunnel entrance, which resulted in large traffic delays.
That causes stuff to be knocked off the top of the truck onto other cars on the road possibly killing innocent people.
Yes, but that would require that the road close for debris to be picked up. The water wall solution allows the tunnel to resume operation quickly. A small jam in the Sydney Harbour Tunnel blocks the whole city, so we want to avoid unnecessarily large delays.
great article but terrible slug -- headline reads like a zippy the pinhead punchline.
The drivers cannot be not simply ignoring the signs.

The sign is telling them that later down the road they will absolutely get in to problems, and get literally stuck. No one would continue with that certainty of getting stuck or in trouble. On top of that, it cant be repeat offenders either. Some one who has been there before must have gotten caught out, one way or another. Its not like drivers on small roads who see a 6ft width restriction sign, but know through local knowledge that really you can squeeze 7ft wide car through the lane.

What we have is drivers who do not know the road, and in their minds don't think the big huge warning signs are meant for them. In their heads they think it for a another driver on the road in close proximity, even if there is no sign of one.

The problem with road signs is making it known to specific individuals that the message is absolutely for them. The brilliant last resort sign absolutely makes it clear who the message is for.

So the key is to some how make driver know that the message is actually for them specifically.

I think truck drivers are more or less trained to ignore everything but the last-resort sign. Near where I live, there's a small bridge (railroad on top, road crosses below) with not enough height. It has some limit on vehicle height that is posted on the streets quite some distance away, so that drivers can choose an alternative route. Of course the bridges always will be higher than the posted limit, taking account inaccuracies of the actual vehicle height and movement during driving, so drivers take a certain amount of leeway for granted.

Now I've seen them back out after having touched the posted bar in front of the bridge and having (almost or actually) touched the structure countless times.

Probably with the consecutively more noticable signs in the video, it's made such that the later signs trigger just at slightly bigger heights than the earlier ones, to avoid scaring drivers that made it through the earlier ones un-warned. So I can see that a driver would try testing the later ones, just because he's pretty sure that he might fit, eventually.

In the US, there's a system called PrePass[1]. It's intention is to be used to allow a truck to bypass weigh-ins. The in-vehicle transponder has a red and green light on it. It could be repurposed to flash red when the vehicle triggers a too-tall warning, though this would be of minimal benefit since it's a small flashing red light most likely in the driver's peripheral vision.

However, I'm unsure if there's any similar system in place in Australia (or most other countries, for that matter.)

[1] http://www.prepass.com/services/prepass/Pages/PrePassTranspo...

I have always felt that this is an issue, as i have personally had many problems when interpreting road signage.

For example, i once pissed off some builders by following a truck into their work zone (they were working on a highway lane). The truck had a huge sign on the back that said 'do not follow into work zone', but how can i possibly know if i'm following a truck into a work zone without some indication of where the work zone is? There were no other signs or lights or orange barrels or anything.

Another example is the way exit ramp signage is written where i live. Highway signs don't include units of measure when they refer to distance, so the first few times i saw the sign 'ABC ROAD — 2' i had no idea that it was telling me that the exit for Abc Road was in 2 MILES, not that i was meant to take Exit 2, which happened to be the very next exit after the sign.

The 11foot8 Web site linked elsewhere in the thread mentions that the rail bridge has a flashing sign that says 'OVERHEIGHT WHEN FLASHING'. The site calls this 'pretty good' signage. It makes sense sitting at my computer reading about it, but i can almost guarantee that if i was seeing that sign for the first time on the road i would have absolutely no fucking idea what it was talking about until after i had already crashed into the bridge.

etc.

The first three or four times I read this post title, it made no sense at all to me. It might as well have read "Sydney tunnel correct horse battery staple". Once I clicked through to the article it made sense, but this is one of the few times I wish the mods had edited the title to match the article.
Eventually the tunnels will have "soft walls" which send large trucks a remote-braking command if collision seems likely... and the trucks themselves collision-avoidance radar. And soon after that all the trucks will be self-driving.
This would make Speed interesting.