Coefficient of rolling resistance of Irish roads

tunney · 19-04-2019 10:05pm #1

Anyone got any idea of the coefficient of rolling resistance of the average Irish national and regional roads?

ednwireland · 19-04-2019 10:07pm

heavy

tunney · 19-04-2019 10:14pm

ednwireland wrote: »

heavy

Noted.

If you could convert that to a number to 6/7 decimal n places it would be great.

Pkiernan · 19-04-2019 10:15pm

tunney wrote: »

Noted.

If you could convert that to a number to 6/7 decimal n places it would be great.

3.1415

secman · 19-04-2019 10:19pm

Heavily pot holed ?
Moderately pot holed ?
Tarred and heavily gravelled but not rolled ?
Patched and patted by shovel ?
No easy answer !

Buzwaldo · 19-04-2019 10:34pm

Love the way they come along and put down lovely flat ‘tarmac’ surface - a pure dream to cycle on - then a few weeks later come along and tar and chip on top of that.
Fierce buzz up through the handlebars, not to mention all the loose chippings on it (for a few weeks until they get flung away into the ditch by traffic).
Sorry OP, not the mathematical input you were looking for.

Wildly Boaring · 19-04-2019 11:17pm

Buzwaldo wrote: »

Love the way they come along and put down lovely flat ‘tarmac’ surface - a pure dream to cycle on - then a few weeks later come along and tar and chip on top of that.
Fierce buzz up through the handlebars, not to mention all the loose chippings on it (for a few weeks until they get flung away into the ditch by traffic).
Sorry OP, not the mathematical input you were looking for.

The flat tarmac is probably a cheap DBM.
It has no skid resistance but is always the layer below wearing coarse. It is laid as build up for longevity and/or to regular unevenness.

Tar and chip is by far the cheapest wearing coarse. SMA or HRA, the proper wearing on a motorway, N road or many R roads is far, far dearer.

With no figures in front of me. Tar and chip is max a fifth the price of the proper surfaces

Buzwaldo · 19-04-2019 11:32pm

Wildly Boaring wrote: »

Buzwaldo wrote: »

Love the way they come along and put down lovely flat ‘tarmac’ surface - a pure dream to cycle on - then a few weeks later come along and tar and chip on top of that.
Fierce buzz up through the handlebars, not to mention all the loose chippings on it (for a few weeks until they get flung away into the ditch by traffic).
Sorry OP, not the mathematical input you were looking for.

The flat tarmac is probably a cheap DBM.
It has no skid resistance but is always the layer below wearing coarse. It is laid as build up for longevity and/or to regular unevenness.

Tar and chip is by far the cheapest wearing coarse. SMA or HRA, the proper wearing on a motorway, N road or many R roads is far, far dearer.

With no figures in front of me. Tar and chip is max a fifth the price of the proper surfaces

Interesting.
For the uninitiated , what do DBM, SMA and HRA stand for?

Wildly Boaring · 19-04-2019 11:44pm

Dense bitumin macadam
Stone mastic asphalt
Hot rolled asphalt.

DBM is just your basic tarmac/asphalt. Has poor skid resistance. May have contributed to Navan bus crash as vehicles where running on it.

SMA is like DBM but has very angular stones in it and once top fat is worn off, it has decent skid resistance. It's use is under a bit of scrutiny as the skid resistance isn't as proven as it's supposed to be.

HRA is a very sandy asphalt with small particle sizes. While still hot, angular stones are spread on it and rolled in to the surface. Most expensive.

There are other wearing coarse but these 2 and tar/chip be most common a cyclist would encounter

Wishbone Ash · 20-04-2019 8:24am

Buzwaldo wrote: »

Love the way they come along and put down lovely flat ‘tarmac’ surface - a pure dream to cycle on....

That's a sort of 'undercoat' which, as Wildly Boaring has said, has no grip. It has been cited as the reason for several fatal accidents.

tigerboon · 20-04-2019 8:00pm

Wildly Boaring wrote: »

The flat tarmac is probably a cheap DBM.
It has no skid resistance but is always the layer below wearing coarse. It is laid as build up for longevity and/or to regular unevenness.

Tar and chip is by far the cheapest wearing coarse. SMA or HRA, the proper wearing on a motorway, N road or many R roads is far, far dearer.

With no figures in front of me. Tar and chip is max a fifth the price of the proper surfaces

It's not really a fifth of the price. A primer coat is applied first to fill voids and prevent too much soaking of the bitumen in the main layer. This ensures bonding of the chip. The 2 layers combined are about half the price of a SMA. When you add site costs like additional traffic management and sweeping up the loose chipping it's probably about 60 per cent.
To answer the OP, I don't think the rolling coefficient is something that is measured. Texture and skid resistance is.

nilhg · 20-04-2019 8:34pm

tunney wrote: »

Anyone got any idea of the coefficient of rolling resistance of the average Irish national and regional roads?

Seemingly your tyres make a big difference

https://www.cyclingpowerlab.com/TyreSelection.aspx

As for some indicative figures the setup for the powerpod PM requires selecting a tyre/pressure/surface combination to generate a typical Crr, a premium grade clincher @110psi givest the following

Wooden track 0.0010
Smooth Concrete 0.0021
Good Asphalt 0.0042
Asphalt Blend 0.0052
Rough Asphalt 0.0083

Wildly Boaring · 20-04-2019 8:43pm

tigerboon wrote: »

It's not really a fifth of the price. A primer coat is applied first to fill voids and prevent too much soaking of the bitumen in the main layer. This ensures bonding of the chip. The 2 layers combined are about half the price of a SMA. When you add site costs like additional traffic management and sweeping up the loose chipping it's probably about 60 per cent.
To answer the OP, I don't think the rolling coefficient is something that is measured. Texture and skid resistance is.

Fair enough.

Was an educated stab.
Depends on your project too.

I manage a lot of utilities jobs. Comes in about 5 times dearer for us to do a real surface to a lane width over spray and chip.

Takes substantially longer. Need to plain entrances and tie-ins. If only doing one lane we also need to sort the longitudinal joint. TM way harder esp for HRA. The chipper and 2cx to load need space. Adjust ironworks. Crew and a half for HRA.

Basically we avoid HRA and SMA at all costs. Often offer council a payment to avoid.

Daroxtar · 20-04-2019 8:44pm

The road surfaces I've been on in Spain and France seem to have a far smoother grade of stone but still have great grip and feel fast under the wheel. I'm not talking big wide roads either, some are narrow goat tracks up nasty inclines and have potholes and cracks too but the surface just feels so much better.
Can't figure out why we keep getting the crap chip and seal when there are obviously other alternatives. It can't all be down to cost as some of the areas I've been in are very remote and not in any way wealthy. There are often rows between local authorities about the funding of road upkeep and yet they can avoid cheap tar....

Daroxtar · 20-04-2019 8:47pm

Wildly Boaring wrote: »

Basically we avoid HRA and SMA at all costs. Often offer council a payment to avoid.

^^^Yeah, now that seems to be par for the course here

Gerry · 20-04-2019 9:00pm

Daroxtar wrote: »

^^^Yeah, now that seems to be par for the course here

That's a bit mental.. do the council not specify a particular surface in the tender??

tigerboon · 20-04-2019 9:06pm

Daroxtar wrote: »

The road surfaces I've been on in Spain and France seem to have a far smoother grade of stone but still have great grip and feel fast under the wheel. I'm not talking big wide roads either, some are narrow goat tracks up nasty inclines and have potholes and cracks too but the surface just feels so much better.
Can't figure out why we keep getting the crap chip and seal when there are obviously other alternatives. It can't all be down to cost as some of the areas I've been in are very remote and not in any way wealthy. There are often rows between local authorities about the funding of road upkeep and yet they can avoid cheap tar....

There's a period of time required for bitumen to wear and expose the aggregate. During this period the road can be slippy in wet conditions. Road surfaces being slippy when wet is not news. However, if an accident happens, the first thing looked at is the skid resistance. Not the crap driving or if the driver was on the phone or if there's €30 half plastic tyres on the car. There's always variations in skid resistance depending on age, aggregate used etc so it's an easy target for the legal industry. Councils probably use surface dressing as the aggregate is exposed from the start giving them the right results.

Wildly Boaring · 20-04-2019 9:33pm

Gerry wrote: »

That's a bit mental.. do the council not specify a particular surface in the tender??

Dont work for the council.

We dig up their roads and reinstate.
There is a "Purple book " for reinstating L and R roads. TII guidance for N roads.

Council can also chance appending special conditions over and above but generally wont happen as we'd just not bring broadband or gas or water or whatever to the area and they'd be shat on.

Generally purple book says if road is under "9" in condition = tar and chip to lane width.
9 is perfect or near perfect. Any road under 5 years old in here usually. Some less trafficked older.
9 plus means match previous to full lane.

TII not 100% so I wont guess without looking. Harsher on trenches and most N roads are SMA or better

Wildly Boaring · 20-04-2019 9:37pm

tigerboon wrote: »

There's a period of time required for bitumen to wear and expose the aggregate. During this period the road can be slippy in wet conditions. Road surfaces being slippy when wet is not news. However, if an accident happens, the first thing looked at is the skid resistance. Not the crap driving or if the driver was on the phone or if there's €30 half plastic tyres on the car. There's always variations in skid resistance depending on age, aggregate used etc so it's an easy target for the legal industry. Councils probably use surface dressing as the aggregate is exposed from the start giving them the right results.

Also councils will not put SMA on a road they don't have on a salting (gritting) route.

HRA is too dear. So most L roads get tar and chip.

ED E · 21-04-2019 10:45am

Do any councils inspect 3rd party works that they actually conform? The Dublin ones appear not to.

Lumen · 21-04-2019 11:46am

With the slightly ludicrous amount of choice now available in big tyred road bikes, I'm surprised anyone cares much about road surfaces.

I quite like the Wicklow gravel around where I live. It adds a frisson to every ride.

outfox · 21-04-2019 9:45pm

Cork County Council are obsessed with tar and chip. The bigger the chip, the better. Other Councils seem happy to use a small chip. Not Cork CC tho.

hesker · 21-04-2019 11:41pm

outfox wrote: »

Cork County Council are obsessed with tar and chip. The bigger the chip, the better. Other Councils seem happy to use a small chip. Not Cork CC tho.

Like the lovely coastal route from Kinsale to Timoleague. Imagine if that was smooth tarmac

outfox · 28-04-2019 4:15pm

Yeah, that road is a headwreck.

Thargor · 18-07-2020 9:40pm

hesker wrote: »

Like the lovely coastal route from Kinsale to Timoleague. Imagine if that was smooth tarmac

Wow looks great, never heard of it:

https://www.google.com/maps/@51.6474786,-8.6953815,3a,75y,172.49h,69.13t/data=!3m6!1e1!3m4!1stR2iYr0R3l9MO3XtjEGW7Q!2e0!7i16384!8i8192

Thats on the to-do list next time Im down there, chippings or not.

magicbastarder · 18-07-2020 9:53pm

i drove that last year, wasn't fun with cars, vans, and camper vans along it with poor sight lines at inadvisable speeds.
a friend was on it two weeks after we were and lost a wing mirror to a camper van.

n1ey · 20-07-2020 6:13pm

tigerboon wrote: »

It's not really a fifth of the price. A primer coat is applied first to fill voids and prevent too much soaking of the bitumen in the main layer. This ensures bonding of the chip. The 2 layers combined are about half the price of a SMA. When you add site costs like additional traffic management and sweeping up the loose chipping it's probably about 60 per cent.
To answer the OP, I don't think the rolling coefficient is something that is measured. Texture and skid resistance is.

It always wears faster. Many consider it a false economy in America. The new research into HRA with tints to reduce heat build up is leading to the best in practice.

Mercian Pro · 20-07-2020 8:55pm

From a similar debate to this a few years back, one poster quoted a roads engineer in Kerry who claimed that HRA was unsuited to roads where there might be any slight movement or settlement of the base layer. I was thinking of this on the Military Road south of Sally Gap where there's a variety of road surfaces including some great smooth ones with no chippings and presumably bog underneath. I know the foundations were put in by the British Army over 200 years ago but they were hardly that good.

CramCycle · 20-07-2020 9:07pm

Wildly Boaring wrote: »

The flat tarmac is probably a cheap DBM.
It has no skid resistance but is always the layer below wearing coarse. It is laid as build up for longevity and/or to regular unevenness.

Tar and chip is by far the cheapest wearing coarse. SMA or HRA, the proper wearing on a motorway, N road or many R roads is far, far dearer.

With no figures in front of me. Tar and chip is max a fifth the price of the proper surfaces

But when you have to replace it so often, there is no way it is actualy that much cheaper, I imagine when you add in man power, complaints, traffic reduction, it costs more in the long run but Ireland doesn't do long runs, it does year to year, which is mental.

tigerboon wrote: »

There's a period of time required for bitumen to wear and expose the aggregate. During this period the road can be slippy in wet conditions. Road surfaces being slippy when wet is not news. However, if an accident happens, the first thing looked at is the skid resistance. Not the crap driving or if the driver was on the phone or if there's €30 half plastic tyres on the car. There's always variations in skid resistance depending on age, aggregate used etc so it's an easy target for the legal industry. Councils probably use surface dressing as the aggregate is exposed from the start giving them the right results.

This I am also skeptical on, a road near me in Wexford and the lovely smooth coating, and a driver went into the ditch. Everyone blamed the road. BS,driver was speeding and knowing the driver, not fully focused. I went round that road faster than i had when it had been a potholed mess without issue. Needless to say, tar and chip went on it soon after, several scrapes of the edge of the road and skid marks as cars take it to fast. There is alot less grip IMO at lower speeds as if i locked up the brakes at a suitable speed, I'd skid on the chippings. At this point, I wish they had just left like the surface of the moon, it was safer.

Wildly Boaring · 20-07-2020 10:10pm

CramCycle wrote: »

But when you have to replace it so often, there is no way it is actualy that much cheaper, I imagine when you add in man power, complaints, traffic reduction, it costs more in the long run but Ireland doesn't do long runs, it does year to year, which is mental.

See the problem is essentially the foundations.

The roads we're all worried about are minor roads. They generally have a terrible foundation.

To do a proper job you'd want to pull the whole lot out and start again.

So you're left with half assed regardless.

You go and fire in full HRA it'll probably pothole just as quick as a thin layer of DBM and tar and chip.

So do the cheapest......

crosstownk · 20-07-2020 10:51pm

CramCycle wrote: »

but Ireland doesn't do long runs, it does year to year, which is mental.

Wildly Boaring wrote: »

So do the cheapest......

Speaks volumes really.

Coefficient of rolling resistance of Irish roads

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