UK roads, constuction spec & traction

Discussion in 'Lounge' started by Mattie660, Jul 26, 2018.

  1. Mattie660

    Mattie660 Elite Member

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    Watching a UTube vid about bikes going round corners, and traction - except it was a US vid.

    He mentioned that the US highway specification had to provide lateral grip up to 1.1 g.

    This must mean that the road surface is sufficiently rough to provide this level of grip - as part of its design specifications.

    He said what this means is that on a normal day, you will not run out of grip going round a corner on a Harley because the floor boards (whatever they are called) will ground out before the bike leans sufficiently to generate the 1.1 g of sideways force.

    Sportsbikes can achieve this with a lean angle of 45' or more.

    So what about the UK ?

    I have just had a look through the Highway Construction Specifications but it does not mention specific lateral G force criteria.

    So what is going on in Britain - is there a G force spec and what is it - will the road spec just not be sufficient to allow big elbow down leaning - no matter how good you are - 'cause the road spec is just not up to it ?

    Does anybody know ? it would be interesting to know what UK spec is

     
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  2. Naz

    Naz Active Member

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    I don’t know what the spec is but I do know that when the materials chosen, as there is a variety to choose from, they must provide a certain level of grip for cars, motorcycles and bicycles. A issue was raised earlier this year or late end of last year about the new cycle lanes in central London and how they are not providing sufficient grip for bicycles and the new road surface adjoining again was inadequate for motorcycles as a few accidents had occurred and the surface was being blamed
     
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  3. Manofsteel

    Manofsteel Well-Known Member

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    the rating used in the UK is PSV or polished stone value this relate to the skid resistance of any tarmac surface laid
    upload_2018-7-27_16-27-2.png
    a word of warning though some newly laid surfaces are more slippery than the old surface until they are rubbered in by traffic especially surfaces in SMA (stone mastic asphalt)
    hope this helps
     
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  4. nigelrb

    nigelrb Elite Member

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    Very interesting @Manofsteel .

    I wonder if any of us phoned local councils to enquire about the PSV value of our favourite roads, would any officer have the knowledge to answer?
     
  5. Manofsteel

    Manofsteel Well-Known Member

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    a highways inspector is supposed to inspect all major roads for any defects every six months,i doubt he would know what the current psv for the road was only when it was first laid but you have to remember it also depends on the category of road so a class 1 or 0 road will generally require a higher psv than a class 3 or 4 but in the HAUC Spec these amounts are not mandatory just a guideline for local authorities to use or come under the terms "local practices" in other words a get out clause,the HAUC does get updated from time to time but the local authorities don't have to adopt it again "local practices"
     
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  6. gixxerjim

    gixxerjim Active Member

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    manofsteel has answered it, its the psv rating which has to be met for the road. there are numerous tests being carried out when surfacing a road, one is the psv test along with many others.

    one thing which has changed recently is going back how it was, everyhting used to be HRA (hot rolled ashphat). this has next to no skid resistance so has granite chippings placed on it when the ashphalt is warm and rolled in.

    SMA came along, it didnt need the chippings, so you didnt need a chiping gang as part of the laying crew, saved you getting another tractor, chipping machine, you have to weigh it as you lay the chippings so you put enough down, you need less labour and plant and so is cheaper.

    of recent councils are realising the sma isnt lasting as long as the HRA, last year I was back on roads with crews I have worked with before, you couldnt sell a chipper 10 years ago, now you need them again, HRA is more commonplace again,
    chiiping gangs back.

    other thing you will notice is antiskid, this can be on certain corners, but usually up to a roundabout or a traffic light. it can be hot or cold applied but basically is a grippier surface approaching a place to stop.

    chipper below, chippings being weighed in the centre, paver and last one antiskid being put down
     

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  7. nigelrb

    nigelrb Elite Member

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    Thanks @Mattie660 for this thread. Has turned out really fascinating.

    A great wealth of knowledge on this forum - across so many areas/trades/disciplines!:)
     
  8. Mattie660

    Mattie660 Elite Member

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    How interesting.

    Polished Stone Values (PSV); "local practices"; Stone Mastic Asphalt (SMA); Hot Rolled Asphalt (HRA) with granite chippings to name a few terms that are new to me !

    Seems like there is quite a wide range of possible road surfaces around the country, old and new, and still within specification.

    I suppose, as a bike rider, experience counts in being able to assess the road surface - you cannot assume that you can lean the bike the same (all optimal conditions) on every road and be saved by the road specification providing enough grip - as there seems to be quite a wide variety of road surfaces (new and old) and a variety of grip levels - all within specification. As a bike rider that ties in to what you find in reality. The linked video seems to suggest that things are more uniform than they probably are in reality in the UK.

    Seems like a good idea to return to HRA with chippings - probably provides consistently better grip over a longer life. I would think this also has implications for what riding gear we choose to wear - don't want to be sliding along granite chippings on your backside !

    Keep up the good work - the sight and smell of new tarmac being laid is public money being properly spent !
     
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