Motorway Barriers?

silverharp

Has the motorway barrier situation here been cleared up yet. As someone who did his first motorway driving in the UK and Germany I still find it a little disconcerting to not have a metal barrier between both carriageways. I remember the NRA coming in for criticism for not having a central barriers a few years back. Now I know European motorways were build in the 60’s so is what we have “best practice”?
My own intuitive view is that a careful driver has a chance of avoiding accidents on his own side but has no control over a bus or truck coming across from the other direction, however are there stats that say that overall grass median is safer?

mike65

They have decided to install "cheese-wire" style barriers for the most part, though some roads have concrete barriers and others chicken wire, discarded trollies and hedges!

Mike.

Chris_533976

Hedges look good, I have no problem with them. As long as there are crash barriers there too.

darkman2

The hedge is not to prevent an accident but to hide, to some extent, the traffic on the other side of the mainline.

As for the new central barriers, I wouldnt want to be on a motorbike going into that. You would be sliced in half.

Hotblack Desiato

Not only that, but the wire is so low down it won't stop a jeep, never mind a bus or truck.

It's just there to make it look like the NRA / Cullen were "doing something" when the media were getting excited about a couple of crossover accidents. Cullen promised to put in barriers and we got the cheapest (to install), least effective, most difficult and expensive to maintain long term, and most dangerous to motorcyclists barrier possible.

God help us, we've government by Joe Duffy and the Evening Herald front page.

Slice

The median between each direction of a motorway in Ireland is wider than other countries and the NRA uses this instead of crash barriers because it's believed to be safer. The logic being that if a car loses control there is an oppoturnity to regain control of the car in the central median instead of crashing into a barrier. I don't really know if it is safer but Irish motorways are safer than any other type of Irish road as is the case with motorways in other countries as well.

Last I heard the NRA were being encouraged to build future motorways with crash barriers instead of wide central medians because it was contributing to land aquisition costs.

jlang

The land costs for road building have gone up massively in recent years so they are definitely going for minimum width alignments where possible. (Minimum length too - but there's more factors that lead to route selection than road length). Also with design and build schemes, the contractors need to and do manage their costs much tighter than the older scheme where the government picked up the tab for overruns.

Another reason for wider central medians on the earlier motorways was that it would be easier to upgrade to add a third lane without requiring extra land take on the outside of the road. They're having a certain amount of trouble shoehorning a third lane (narrower lanes, tight junctions, lower speed limits) onto the M50 but imagine how difficult it would have been if a narrow median had been used. As the motorways are extended farther from Dublin, and it is questionable even whether a motorway is required at all, this is not as important as the 2-lane-each-way road is plenty future proofed already.

Hagar

Slice wrote:

The logic being that if a car loses control there is an oppoturnity to regain control of the car in the central median instead of crashing into a barrier.

At 120kph you travel 33.33m per second. So if the median is less than that width you have less than 1 second to react and control a speeding vehicle on grass. What do you think the odds of bringing the vehicle back under control are?

Slice

Hagar: At 120kph you travel 33.33m per second. So if the median is less than that width you have less than 1 second to react and control a speeding vehicle on grass. What do you think the odds of bringing the vehicle back under control are?

Well I'm not saying that's my logic but it is the logic behind it. Having been a passenger in a car that carriered off the road and regained control (on secondary road, at slower speed with less room for manouvre) it seems to me that the central median on the motorways would be sufficient for some cases, no?

mike65

The idea is to avoid fatalities on all cases which which case you'd need a median of about 250 metres! Or a sand trap.

Mike.

Hagar

I would agree in some instances the driver could regain control. I would not like to bet my life on it on a wet winter's night. I would like to make the point that other vehicles travelling in the same direction may well be involved and negate each other's attempts to regain control.

Factor in the possible swerving/evasive manouevers taken by approaching drivers even if you don't completely cross the median, human nature will have oncoming drivers trying to avoid a head on crash.

Let's not forget the large number of relatively inexperienced provisional licence drivers, un-accompanied or not, using the motorways and add their abilities to the mix.

I think given the overall cost of building 1km of motorway the cost of the barriers should not have been skimped on and people should not be trying to excuse it. The powers that be should face up to the shortcoming and just put up the barriers.

HelterSkelter

I'm waiting from BrianD to come on and tell us we don't need a crash barrier as we have to take responsibility for our own actions while driving :rolleyes:

BrianD3

Most dual carriageways and M-ways do have barriers now. There are a few different types in use - metal armco, wire rope, concrete "jersey" barriers etc.

The wire rope is actually pretty good at stopping crossovers. Even when hit by large vehicles. From what I've seen the rope barriers seem more effective than the armco ones. Both of these types are nasty for motorcyclists who have fallen off and are sliding along the ground.

Aidan1

At 120kph you travel 33.33m per second. So if the median is less than that width you have less than 1 second to react and control a speeding vehicle on grass. What do you think the odds of bringing the vehicle back under control are?

I'm waiting Hagar to come back to explain how a vehicle travelling at 120kph is supposed to make a 90 degree right turn to cross the central division at a right angle ...

Cos other wise you have a lot longer than 33m to make a correction. Of course, the odds of successfully making that correction without veering back into the lane you just left and causing a collision have to be balanced with the odds of hopping off armco or the cheese wire divider and back into traffic.

The wire rope barrier is definitely better for cars than armco (it tears them up but tends to absorb the impact rather than sending back them out into traffic). It works for trucks too, but one truck accident can mean that a very long section of the barrier has to be renewed. Then again, since trucks are not supposed to be in the outside lane of Mway, it shouldn't be so much pf an issue.

As for bikers, well, I can see why they'd prefer armco, but in reality, if you come off a bike at over 120kph on a Mway or HQDC at over 110kph with other traffic around, what are the odds of survival in any case?

Hotblack Desiato

Aidan1 wrote:

As for bikers, well, I can see why they'd prefer armco, but in reality, if you come off a bike at over 120kph on a Mway or HQDC at over 110kph with other traffic around, what are the odds of survival in any case?

That depends on the circumstances, after all a sub-30mph accident can kill, but glancing off a smooth barrier at a shallow angle causes relatively little injury. Hitting a wire rope barrier is highly likely to result in amputation of limbs or head.

Hoof Hearted

Aidan1 wrote:

I'm waiting Hagar to come back to explain how a vehicle travelling at 120kph is supposed to make a 90 degree right turn to cross the central division at a right angle ...
QUOTE]

Aidan is talking some sense here.

For the sake of completeness if a car travelling at 120kph hits the barrier at a 5° to the motorway (a reasonable assumption), its 90° speed will be 10.5kph (This is the effective sideways speed against the barrier which is really what counts) An analogy is an aircraft landing at 220kph its decent speed is about 6kph on touchdown.

I'm sure the media would never report that a car hit a barrier at 10kph. It really depends on the angle, at 1° the "sideways" speed is 2kph.

Sideways speed x = 120kph X Sin(5°)
x = 10.5kph

Aidan1

but glancing off a smooth barrier at a shallow angle causes relatively little injury. Hitting a wire rope barrier is highly likely to result in amputation of limbs or head.

Thats what I meant when I said I could see their point. However, and personally speaking, I wouldn't like to 'glance off' anything at 100-120kph when only wearing some Kevlar and leathers, regardless of closing/impact speed. In the vast majority of cases, the difference in end result would be minimal in every sense other than optics. For low speed, and low angle of incidence, crashes, then there would be severe differences in result though, making the use of wire on 2+1 and close to junctions very dubious IMVHO.

popebenny16

All of the motorways now have some sort of barrier, mostly the high tension wire one which has been retrofitted on the M7, and on the new Nass road there are a mixture of metal and concrete ones.

The Cashel bypass which is motorway standard (but 100kph limited at the moment) has a concrete barrier all the way along it.

The hedges were the prevent you from being dazzled by the high beams of traffic the other side of the road, nothing else. The wide medians were previously accepted as a substutiution for the barriers. Two fatal accidents on the M50 where cars went straight across and ploughed intoi oncoming traffic have proven otherwise.

Hotblack Desiato

Aidan1 wrote:

Thats what I meant when I said I could see their point. However, and personally speaking, I wouldn't like to 'glance off' anything at 100-120kph when only wearing some Kevlar and leathers, regardless of closing/impact speed.

Neither would I, but as MotoGP proves every other weekend, it's not sliding down the road that hurts you, it's what you hit.
As other posters have pointed out, at a shallow angle the impact against the barrier isn't severe - almost all of your speed is forward speed, the sideways speed is small.
The problem with wire rope isn't the rope, it's the exposed posts, armco has less "open" area for limbs to go through and get caught, and armco can easily and cheaply be upgraded to have hidden posts and no open area. This is impossible for wire rope.

In the vast majority of cases, the difference in end result would be minimal in every sense other than optics.

This is certainly not the case. On a straight high speed road almost all impacts are going to be at a shallow angle to the barrier, because of the high forward speed. Accident scenarios with a steep impact angle are possible but have low survivability with or without a barrier.

For low speed, and low angle of incidence, crashes, then there would be severe differences in result though, making the use of wire on 2+1 and close to junctions very dubious IMVHO.

This is my point exactly, in the most common accident scenario on the type of roads where we use wire rope, it makes a huge difference in outcome for motorcyclists. I think the points about other countries removing wire rope, a likely EU ban eventually, and the high costs of wire rope maintenance are important too.

Hagar

Some nice maths there lads. If any of you are prepared to try and prove any of that theory in real life/death let me know. I'll be somewhere else on purpose. I don't like gore.

It's impossible to predict what angle a vehicle will approach a barrier in a collision. Have you ever seen skid marks on the road that abruptly change direction and head off at an unexpected angle?

Aidan1

Nice maths? Kinda. I still want one of the cars that you have that can make a 90 degree turn at 120kph though. No one is minimising the effect or consequences of accidents here, which is kinda critical.

MotoGP proves every other weekend

Which is why the tracks they use for Moto are conspicuously short of things like road signs, cars and articulated trucks one lane over doing 90-100kph. Added to that, the tracks are a good deal wider than a road lane, and have run off areas/sand or gravel traps. All the Moto example proves is the extent of the safety precautions required for bike racing on a closed circuit. By comparision, look at the things that cause fatalities on TT racing. And thats still without other forms of vehicular traffic.

Were I a biker, I'd prefer a smooth concrete wall on motorways as well, but mainly for the sake of peace of mind. Riding a bike at speeds like that on a public highway is inherently dangerous, as any biker will know. To borrow from an earlier post, thats 33.33ms, with no deformable structure around you. If you hit the wall (or are pushed into it) at 120kph with other traffic around, the chances of surviving it are very slim indeed. 'Glancing off' is not something you do at that speed. Poles or not. The fantasy of sliding serenely into a gravel trap on your back is just that in a world populated by other vehicles, light posts, bridge abutments and trees.

MrPudding

ninja900 wrote:

Not only that, but the wire is so low down it won't stop a jeep, never mind a bus or truck.

Believe it or not they will stop a truck. I remember seeing some video footage a a fully laden 40 foot artic being driven into a wire barrier at 70MPH at an approach angle of 45 degrees. The barrier collected it up and brought it to a halt. Very impressive.

Some google searching may locate the clips.

I personally think the wide median is bull. When the gov is asked why they didn't put in 3 lanes they say "we put in a wide median so we could upgrade easily." When asked why there are no crash barriers they say "we have a wide median to allow drivers time to regain control." Which is it, it can't be for both.

I must admit I used to be of the opinion that the barriers should be in place but I must admit my view has changed somewhat. How many people dies as a result of carriageway cross overs? Not many. I think the money spent retro-fitting barriers could have saved more lives had it been directed somewhere else.

MrP

bk

MrPudding wrote:

I must admit I used to be of the opinion that the barriers should be in place but I must admit my view has changed somewhat. How many people dies as a result of carriageway cross overs? Not many. I think the money spent retro-fitting barriers could have saved more lives had it been directed somewhere else.

I disagree with this, I don't have actual figures, but if you watch the news, you'll see that the most serious accidents where multiple people are killed are almost always head on collisions.

The reason is very simple, the velocity of the impact is the sum of the speed of the two vehicles. So if the two vehciles are travelling at 60km, then the impact is equivalent to a 120km crash.

BrianD3

bk wrote:

I disagree with this, I don't have actual figures, but if you watch the news, you'll see that the most serious accidents where multiple people are killed are almost always head on collisions.

I think the point he was making is that head on crashes on dual carriageways are rare. Even if there is no barrier fitted, they are still far, far safer than single carriageway roads.

I also used to be of the opinion that barriers should be fitted and that it was a disgrace that they weren't. But thanks to BrianD's posts on this forum I have changed my view somewhat. In terms of reducing road deaths the money may be better spent on engineering improvements in other areas eg
-improving visibility of nat secondary and regional roads by cutting hedges
-more/better road markings and catseyes
-making the roads more forgiving of mistakes, for instance removal of dangerous roadside objects like trees and deep ditches

Slice

I'm of the same opinion. Unless there is statistical evidence that barrier free motorways are not as safe motorways where barriers are fitted then the issue of motorway safety is a non-starter really when the fact remains that motorways are the safest roads around.

If anyone wanted to address road safety it should be secondary roads that we should concentrate on...

Hotblack Desiato

Aidan1 wrote:

Riding a bike at speeds like that on a public highway is inherently dangerous, as any biker will know.

:rolleyes:
It's not inherently dangerous. It carries a risk, as any vehicle does, and yes the risk is higher than for some forms of transport, but less than others.
Plenty of pedestrians get killed on the roads but we don't say that walking is inherently dangerous. Is this bias on your part?

If you hit the wall (or are pushed into it) at 120kph with other traffic around, the chances of surviving it are very slim indeed. 'Glancing off' is not something you do at that speed.

Sigh, you just don't get it do you. Forward speed is IRRELEVANT as that component of your velocity is parallel to the barrier. What matters is the sideways velocity into the barrier, which is often a couple of metres per second or less. The inherent problem with wire rope is that it's likely to cause very severe injuries in common situations where a smooth barrier would cause little or no injury to a rider wearing normal protective gear.

popebenny16

How many people dies as a result of carriageway cross overs? Not many.

Isnt one enough?

As I said above it has happened twice on the M50, the last time was when joyriders went over the meridian on the northern cross route and ploughed into a car driven by a priest on the other side, I think three died as a result. It happened before that also on the NCR and there was one fatality.

Also, dont forget our version of the Washington Sniper over in clondalkin who was taking pot shots at truck drivers, any one of them could have resulted in a cross-over.

Finally, if you've ever seen those police video shows on the TV you will have seen plenty of cars and trucks resting against the inner barrier after a crash.

Aidan1

Sigh, you just don't get it do you. Forward speed is IRRELEVANT as that component of your velocity is parallel to the barrier.

Not even close. Closing rate with the barrier, of whatever type, is critical obviously, but the forward speed of the vehicle is equally so when it comes to the interaction between two objects. Are you seriously suggesting that the result of a swipe at 30kph will be exactly the same as one at 120 kph on a bike, so long as the closing rate is the same?

Even leaving out the difference in effect on the bike (in terms of damage and/or the rate of departure from control) or the immediate physical impact on the rider (consider same angle of incidence, same bike, same rider at widely different speeds - the faster you go, the harder the impact), the simple fact that you have much, much longer to slide before coming to a halt means that you have a much greater chance of (a) hitting something solid or (b) being run over.

Tell me, which would you prefer, an accident at 30kph or 120kph? Cos according to you, there should be no difference so long as the angle of incidence remains the same...

It's not inherently dangerous. It carries a risk, as any vehicle does, and yes the risk is higher than for some forms of transport, but less than others.

Risk is sometimes defined as the odds of something happening multiplied by the consequences if it does. On that basis, yes, motorcycling is an inherently risky business because (a) motocyclists have accidents on a regular basis and (b) the odds of a fatality are much higher when that happens, due to fairly straightforward reasons. Its not a bias, its just a fact.

On the broader issue, yes, concrete medians are the ideal, but for the moment, and on the 'open' sections the wire barriers do just fine. On 2+1s and near junctions, concrete or armco is the way to go.

Hotblack Desiato

Aidan1 wrote:

Are you seriously suggesting that the result of a swipe at 30kph will be exactly the same as one at 120 kph on a bike, so long as the closing rate is the same?

Yes, by definition you will hit the barrier with the same force.
Forward speed only causes injury to you if limbs get caught in the barrier - which is what happens with wire rope.

Even leaving out the difference in effect on the bike

The bike is irrelevant, the scenario being discussed is a sliding rider. The rider rarely stays with the bike for long in an accident.

the simple fact that you have much, much longer to slide before coming to a halt means that you have a much greater chance of (a) hitting something solid or (b) being run over.

(b)You're just as likely to get run over if you're doing 30mph before falling off and the driver behind is tailgating you. Irrelevant.

(a) Sliding in a straight line along a straight road, the only thing to hit is the barrier, or objects on the nearside like poles. It's barriers we're discussing here.

Tell me, which would you prefer, an accident at 30kph or 120kph? Cos according to you, there should be no difference so long as the angle of incidence remains the same...

Emotive handwaving about speed isn't relevant either. It's basic physics. The component of velocity at right angles to what you hit is irrelevant to the force of the collision provided you are hitting a smooth surface. A wire rope barrier is an aggressive surface.

On that basis, yes, motorcycling is an inherently risky business

Which is what I said, but so is driving a car or crossing the road, it's just a question of degree.
Saying motorcycling is "inherently dangerous" is another kettle of fish entirely, it's an expression of emotion not a discussion of fact.

MrPudding

popebenny16 wrote:

Isnt one enough?

As I said above it has happened twice on the M50, the last time was when joyriders went over the meridian on the northern cross route and ploughed into a car driven by a priest on the other side, I think three died as a result. It happened before that also on the NCR and there was one fatality.

I know this. Any death is regretable but the fact remains, as harsh as it may sound, deaths from carriageway crossovers in Ireland are a pretty small proportion of the overall death toll. All I am saying is the money spent on barriers *may* have had a bigger inpact on deaths had it been directed elsewhere.

popebenny16 wrote:

Also, dont forget our version of the Washington Sniper over in clondalkin who was taking pot shots at truck drivers, any one of them could have resulted in a cross-over.

But did it? It is all very well saying what might have been but we have people actually getting killed right now on ****ty roads.

popebenny16 wrote:

Finally, if you've ever seen those police video shows on the TV you will have seen plenty of cars and trucks resting against the inner barrier after a crash.

So what? We know it happens. The point is it doesn't happen very much. There is a finite amount of money available and it would probably be better spent elsewhere.

MrP

bk

I agree that cross-overs are less likely on Motorways, but they still do happen. A particular problem is when people fall asleep at the wheel. It is called micro sleep, the person falls asleep for only a second, but that is often enough for them to swerve into oncoming traffic. What is particularly scary is that it is quiet common amongst lorry drivers because of the long hours then spend of the roads. A 18 wheeler crossing over is not good.

I certainly agree with BrianD3 that there are other things that can also be done to improve safety, but I don't think it is one or the other, there should be doing all of them.

The thing with BrianD3 ideas is that they help single vehicle accidents (or just cars going in the same direction), but not cross overs (except perhaps the cats eyes), I'll repeat, cross-over accidents are far more serious then single car accidents as they double the speed, therefore almost always causing more serious, often fatal accidents. Another thing I don't like about them is that they often kill innocent, safe drivers.

Lets be honest most accidents are caused by drinking or too much speed. If a drink driver hits a tree, that is very sad for the family, but they did it to themselves. However if they cross-over then they can be killing the safest driver in the world and that is what frighten me when I'm driving, other incompetent drivers.

But here is the thing, when building new motorways, barriers only cost a fraction of the overall cost, barely worth talking about, so I think we can all agree that they should be fitted on all new roads and should be fitted on older roads when money permits.