New roads can be slippy!!!

[Daz]

Did anyone watch Real Story tonight? It was scary stuff. They were investigating the state of Britain's roads. It showed how a newly layed road can be slippy in the dry :shock: Apparently just as slippy as a wet road :shock:

They said, that if you see a slippery road sign, to treat the road like a wet road. After a while the surface will wear and it will be ok.

It is cause by a newer design of road surface. Hopefully someone here, who has seen the program, can explain it.

Also, we all know that the overbanding, used to seal road repairs, can be dangerous, especially in the wet. However, one of the accidents they investigated showed that the overbanding was faulty and caused a biker to die :(

Real Story (http://news.bbc.co.uk/1/hi/programmes/real_story/4607181.stm)

[adam]

http://forums.sv650.org/viewtopic.php?t=25180

[hall13uk]

it was a sobering program the main point was recently (last 10yrs) a new road type that is easier to lay & cheaper to produce has a lot of oil in it when first layed, so when your tyre skid's on it & produces friction the oil is raised to the surface under the heat. so making the road as dangerous as if it was covered in standing water, many cars have aquaplaned on it. This new road surface is due to be layed on 60% of british roads my 2010, many of these roads now have sikd warning signs but onl after a police investigation was carried out.

[fizzwheel]

Now this is going to sound harsh, so I will apolgise in advance.

I dont get what the sudden revelation in new tarmac roads will be slippery fuss is all about.

I've been out an about on the roads since I was a kid, I used to ride a very super light push bike pretty fast then I moved onto four wheels and now I am back to two again.

I've always treated newly laid tarmac with utter discontempt whether it be shiny and smooth, or covered with stone chips which move about and give no grip what so ever. Also its new so how can you judge how much grip or anything you are going to get back from it. Tarmac that has been down for a while has weathered so you can normally judge it by the colour, is it shiney kind of things.

Ever watched tarmac being laid, no go and watch it, watch what they do, watch all the oil and bitumen form a slick over it once they've laid it.

Its not a new thing, newly laid tarmac is slippery it always has been. Sorry if this upsets anybody, but this kind of thing I think just about sums up the nanny state we live in now.

As for the overbanding issues on that program tonight, well thats different completely, but again I dont trust overbanding and I will if possible try ad avoid riding over it.

[Carsick]

Its not a new thing, newly laid tarmac is slippery it always has been
Good point and well made.
It's true and I have confirmed it myself more than once.
Managed to get myself into a situation where I had to do an e-stop up a fairly steep hill, from about 40mph and managed to slide quite badly. Still stopped in time, but that's not the point.

[21QUEST]

Now this is going to sound harsh, so I will apolgise in advance.



Don't think you needed to apologise. As previously said , good post.

Newly laid roads look look wet and slippery for Petes sake :roll: . If people need a program to tell them that then maybe they should not be driving/riding.

With regards to living in a nanny state people complain about that yet they almost ask to be nannied .

[BillyC]

Fizz,

Good point, and you're absolutely right. However, I think the programme (I didn't see it) may have been looking at a particular type of road surface that has been banned in many European countries.

Unlike most road surfaces, this kind (I've forgotten the name) can take YEARS to bed in! :shock: While I appreciate that very new roads take a little while to settle down, compact, and wash off the excess, this surface can go through all that, and still tripple your stopping distances.

Something similar was posted on here a few months back, from a Radio 4 programme talking about roads in general. On it, was a Police motorcyclist who witnessed a colleague infront of him, lose his front wheel on a bend, at a reasonable and acceptable speed - and crash into an oncoming car, killing him instantly. The copper couldn't understand why.. the road was good condition, the conditions were dry, the speeds weren't high... but on closer inspection, the surface joins were too large, and the surface was of this "banned" type.

[fizzwheel]

The road surface the were talking about was called SMA or something like that

I cant remember what it stood for though.

[Warren]

a patch of old tar that has been used to repair roads can be just as slippery in the sun.



just thought id point that out.

[Captain Nemo]

The road surface the were talking about was called SMA or something like that

I cant remember what it stood for though.


Captain Nemo is a Highways Engineer and pavement specialist so here goes..

forgive me if im preaching to the educated..


SMA= stone mastic asphalt.

SMA is the (generally) prefered option being adopted by many Highways Authorites, it is not currently permitted for use by the Highways Agency so it will be unusual to find this material on trunk roads or motorways.

this is partly down to known problems with early skidding resistance and high speed roads, and partly down to namas (the labs that approve material) approval and quality control.

ALL SURFACINGS have a reduced psv (polished stone value) when newly laid, this includes traditional hot rolled asphalt surfacings as well as proprietry sytems such as shelltex and britpave.

this is because of several points,
1, then binders used to hold the aggregate together needs to be worn slightly to reach max psv
2, the binders need to be worn away slightly to allow the micro tecture of the aggregate to be exposed above the level of the binder, the aggregate provides the skidding resistance
when a surface is freshly laid the aggregate is slighly "embedded" into the binder as the binder wears this is less noticable.

SMA wearing course is not cheaper to buy and lay than other systems, in fact SMA is less tollerant to being laid at low temps or in wet weather, however SMA does exhibit cost savings due in less maintenace being required during its servicable life.

because reduced aerly resistance to skidding it is a recognised feature of SMA wearing courses manufacturers tailor the design mix to take account of this for example

if a road requires a PSV of 60, it may be that the psv of the material when freshly laid is say 57, the manufacturers produce a mix that will give an initial psv of 60, this will rise over the first few months to around 62-63

a lot has been made of SMA surfacing "failing" skid resistance tests, this is not strictly true, some SMA testing has shown that the mix has fallen below its design resistance, but that doesnt neccesarilly mean that it is nusafe to use in the locations it has been laid..

The Highway code says that motorists should drive to the conditions at the time, if a corner looks slippery it usually is.

knowing what i know about surfacing sometimes makes me very wary of surfacing conditions.

"slippery road ahead" signs are often used on sections of new SMA surfacing as well as on surfacings that are on there way out adn have fallen below the intervention level for skid resistance, these signs can only be used for max 6 mths before action has to be taken, and they dont negate the highway authorities responsibilities, although this wont be much comfort if your sliding on your **** watching your bike go into a field...

sorry to be longwinded but it is rocket science after all.

incidentally i am a more interesting person than this post suggests
:oops:

[Stormspiel]

As a fellow highways technician (albeit trainee :lol: ) can i say well done on your description of the pros and cons of SMA ... and can i borrow you to do my HNC next year Ha Ha Ha :lol: :lol:

[Captain Nemo]

As a fellow highways technician (albeit trainee :lol: ) can i say well done on your description of the pros and cons of SMA ... and can i borrow you to do my HNC next year Ha Ha Ha :lol: :lol:

If you do my IPR submission for me :)

[Warren]

sorry to bump this thread . . .but dont suppose anyone has the link to the radio program about SMA highway where the biker lost his life ?

cheers

[OF.uk]

incidentally i am a more interesting person than this post suggests
:oops:

No you're not :wink: :lol: :lol: :lol:

[kwak zzr]

i lost the front on my cbr about 2 years ago,it was bone dry but the new road had a shiny surface to it.when i picked up what was left of the cbr and put it on the stand i then went to where i lost grip and the road was simalir to ice (very oily) i never take grip for granted now on new roads!
i'd been aware that new roads were slippy but i just didnt realize how bad they can be.
daz