Concrete carriageway dividers

[Enceladus]

Pretty much all the sections of motorway built in Ireland since 2005 have concrete central barriers. The older sections of motorway have wide grass medians with wire-rope barriers which must be lethal to motorcyclists if they hit them.

I suspect the newer motorways with concrete barriers were standard policy as it is easier and faster to build them as one wide road surface and then slap the concrete barrier in the middle to separate the two carriageways. Also less land take too.

TBH I didn't like the concrete barriers at first but I do appreciate their safety benefits and have got used to them at this stage.

[GrahameCase]

Another illustration as if any was needed that Armco barriers are woefully inadequate for motorway use : http://www.bbc.co.uk/news/uk-england-gl ... e-41294963.

Any help but feel that a concrete barrier would have deflected or arrested this lorry much better

[WHBM]

Concrete barriers of the current design will restrain cars fully but not necessarily HGVs, depending on the speed, weight, and angle of strike.. They can also overturn over the top of them, as I witnessed with a tipper truck on the M25.

They also deflect the striking vehicle back into their carriageway, commonly having put them into a spin, when collisions will also ensue. This now applies to cars, whereas the old Armco, which is quite a sophisticated engineering product, would typically contain them off-carriageway in the median.

As I understand it their justification was nothing to do with road user safety, but a H&S conclusion about the risk to work crews who go out to repair Armco strikes, concrete requiring less frequent repairs. I sometimes wonder if the review was correctly multiplied by the far extended duration of works when such concrete repairs are required.

It is quite possible to specify rapid-cure concrete of the same strength which has additional chemical additives, as used in overnight concrete carriageway repairs on the concrete M25. It is more expensive than Plain Jane, 30 Newton stuff, but presumably any additional material cost comes out of the repair budget, whereas the huge delay time to road users does not.

[Stevie D]

They also deflect the striking vehicle back into their carriageway, commonly having put them into a spin, when collisions will also ensue.

My gut feeling is that this would be significantly less hazardous than a crossover where a lorry continues at some speed on the opposite carriageway, in terms of the closing speed of vehicles at the time of the collision and the better likelihood of other drivers anticipating what is about to happen and taking preemptive action to avoid it.

[TheKeymeister]

Wasn't there a 'cheapening' of the new concrete barriers a few years ago?
If I remember right, the old ones used to be dug out and sunk into the ground, whereas the new ones just sit on the top of the surface. Surely this lessens their effectiveness for restraining an HGV crossover.

[darkcape]

I think all concrete barriers are embedded into the ground in central reserves.

[M&T's Dad]

I'd like to see some solid evidence about what happens when 44 tonnes of vehicle hits various types of barrier at nearly 60mph. I doubt anything the government is willing to pay for would make much difference in circumstances like this, though. Regardless of the barrier, other road users were going to be killed or injured by uncontrolled machinery with that amount of momentum.

[Helvellyn]

They also deflect the striking vehicle back into their carriageway, commonly having put them into a spin, when collisions will also ensue.

My gut feeling is that this would be significantly less hazardous than a crossover where a lorry continues at some speed on the opposite carriageway, in terms of the closing speed of vehicles at the time of the collision and the better likelihood of other drivers anticipating what is about to happen and taking preemptive action to avoid it.

Probably, although a lot will depend upon circumstances. Straight through and across the carriageway quickly might be less hazardous than spinning around for a bit collecting nearby traffic, although the traffic on the same side will probably have more time to react and avoid.

[Reading]

Armco and the steel rope barriers are also worse for motorcyclists as they have verticals which can be slid into at speed http://www.worldhighways.com/categories ... rcyclists/