This morning's M25 crash, and concrete barrier safety.

[The Natural Philosopher]

On 10/12/14 12:35, "Nightjar

[dennis]

They will stop cars and glancing blows from lorries but you need a lot more material to stop a 40 ton lorry. The best way to design a motorway is to ignore the greens and build the carriageways 50 yards apart. The "wasted" space between would be good for wildlife.

[Adrian]

On Thu, 11 Dec 2014 09:11:11 +0000, Nightjar >>>>>>>> The best way to design a motorway is to ignore the greens and

If the Highways Agency bought enough land up, there could be enough central reservation to put as much width as you like between the carriageways...

Doing so on the M25 might be tad problematic, politically, especially given that many stretchs CANNOT be widened any further without compulsory purchase of quite a few rather expensive houses.

[JTM]

Repair /replacement of metal barriers isn't cheap or convenient either. - close a lane in each direction for several hours with a team taking several hours to do the work following even a minor incident.

I see the concrete barriers on the N340 (Med coast road) has eveidence of many many collisions and doesn't (usually) need remedial work

John

[Nightjar]

On 11/12/2014 09:19, Adrian wrote: ...

Put them far enough apart and they don't need to own the land between the carriageways, as with the sheep farm in the M62 central reservation.

The point is you don't need to widen the existing motorway. Follow the concept of the original Ringways scheme and build another ring motorway well outside it. However, instead of having them as two-way motorways, use the full width of the existing M25 for traffic travelling in one direction and build the new motorway just as wide, for traffic travelling in the other direction. The existing M25 could even be kept as two separate carriageways, both travelling in the same direction, but with limited access to one carriageway, so that long distance through traffic does not need to mix with local commuter traffic.

[bzooow]

e will sit in a boat drink beer all day.

Not sure on the comparable cost/time of replacement but metal barriers alwa ys seem to be replaced pretty quickly whereas the currently damaged concret e M25 barrier is still not repaired after three days. Not sure when it's sc heduled but with "40m" needing repair and "time for concrete to set" being required total disruption time seems a lot higher for damaged concrete barr iers.

[bert]

You could always put a high speed train up the middle

[news]

That's strange because I thought they were anchored by 24mm rebar. The reason being in the 80s a welsh engineering firm that built forestry harvesters had developed a device using compressed air for firing such rods 7 metres into the ground and installing crash barriers was one of the jobs touted. The other one was doing the same with well point tubes to collect gas from landfill.

The base projector was allegedly surplus from a soft launch system from Porton Down.

AJH

[meow2222]

A goods train might make better economic sense. Perhaps design it to take truck trailers whole.

NT