Coefficient of rolling resistance of Irish roads

tunney

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

ednwireland

heavy

tunney

ednwireland wrote: »

heavy

Noted.

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

Pkiernan

tunney wrote: »

Noted.

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

3.1415

secman

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

Buzwaldo

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Lumen

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

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

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

Yeah, that road is a headwreck.

Thargor

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

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

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

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

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

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

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.

CramCycle

Wildly Boaring wrote: »

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......

Could you not put the cheap smooth layer and warning saying "Oi, f*ck hole, the road is slippy, always, drive to fast and your insurance is invalid, because, well, your a f*ckhole". I presume is will crack and break, and pothole as well but at least your not risking cyclists, and damaging cars or pedestrians.

Wildly Boaring

crosstownk wrote: »

Speaks volumes really.

I'd stand by my comment actually.
The cheapest is probably the most prudent course of action in the circumstances.

Full job not financially viable unless we stop funding to any other sort of transport project and focus on full rebuild to 100 year old roads.

Tar and chip has it's place. We as cyclists suffer for a few weeks after but ultimately if the council were forced to run s sweeper weekly it'd sort itself pretty quickly.

Unfortunately for that to happy probably need to suffer s few claims or be forced some other way.

outfox

Wildly Boaring wrote: »

Tar and chip has it's place. We as cyclists suffer for a few weeks after but ultimately if the council were forced to run s sweeper weekly it'd sort itself pretty quickly.

Unfortunately, it's not just a few weeks. Even after the loose chippings are cleaned off, the road is still sh1te because the new surface just settles on top of the original crappy surface, like throwing a new table cloth on a table without removing the plates. So the finished road is still bumpy, and gets worse after a year or 2. And of course the chips wear off from car tyres, so you get dangerous transition zones between chipped and unchipped parts. And then we get the bitumen melting on a hot day, throwing tar spots and grit all over cars/bikes. Tar and chip is the devil IMO. I can see why local authorities use it. It offers instant skid resistance, and is much kinder on limited annual budgets.

Council's should remove third class roads from their maintenance programmes, and use the money to bring regional roads up to scratch. If you chose to live in the arseh0le of nowhere up a third class road, tough. I say that as someone who lives up a third class road.

Don't get me started on contractors who carry out trenching works which result in settlement after a few weeks. It's beyond me that they cannot manage to repair the surface so that it stays flush with the surrounding surface.

magicbastarder

outfox wrote: »

Even after the loose chippings are cleaned off, the road is still sh1te because the new surface just settles on top of the original crappy surface, like throwing a new table cloth on a table without removing the plates.

yeah, saw a great example of this on mullaghteelin (just north of snowtown) last year. you could see the outline of old potholes *after* the 'resurfacing'.

Large bottle small glass

outfox wrote: »

Unfortunately, it's not just a few weeks. Even after the loose chippings are cleaned off, the road is still sh1te because the new surface just settles on top of the original crappy surface, like throwing a new table cloth on a table without removing the plates. So the finished road is still bumpy, and gets worse after a year or 2. And of course the chips wear off from car tyres, so you get dangerous transition zones between chipped and unchipped parts. And then we get the bitumen melting on a hot day, throwing tar spots and grit all over cars/bikes. Tar and chip is the devil IMO. I can see why local authorities use it. It offers instant skid resistance, and is much kinder on limited annual budgets.

Council's should remove third class roads from their maintenance programmes, and use the money to bring regional roads up to scratch. If you chose to live in the arseh0le of nowhere up a third class road, tough. I say that as someone who lives up a third class road.

Don't get me started on contractors who carry out trenching works which result in settlement after a few weeks. It's beyond me that they cannot manage to repair the surface so that it stays flush with the surrounding surface.

As a cyclist bad bumpy surfaces have an up side, they will usually have a slowing effect on traffic and will typically veer all but essential motor traffic away from road.

Personally I hate seeing roads repaired with any resurfacing works. I have a 200km route around South Tipp and some sections were like Baghdad alley before this summer. Now 4 sections of it have been repaired. As long you can pick your line a poor surfaced road is typically safer especially for a solo cyclist.

There is 80k km of local roads in Ireland, I'd imagine local authorities would love not to have to maintain them, but I can hear the Healy Raes shouting already.

If LA just enforced the 1993 Roads Act with regard to drainage roads wouldn't need near as much resurfacing.

@Lumens post makes a lot of sense
https://www.boards.ie/vbulletin/showpost.php?p=109985336&postcount=21

In a lot of areas the oversight on works by LA engineer is not very thorough. The manpower is thin on the ground in lots of places

tigerboon

outfox wrote: »

Don't get me started on contractors who carry out trenching works which result in settlement after a few weeks. It's beyond me that they cannot manage to repair the surface so that it stays flush with the surrounding surface.

When pipe laying is carried out the trenches are reinstated but the finished surface is not placed until they're confident settlement is finished. Once full settlement is achieved (might take a year or so), they replace the top bumpy 50mm or so with a lovely smooth final surface. That's the theory anyway.

outfox

That certainly makes sense, tigerboon, to allow settlement. But in the interim, some of the trenches can be messy. We've had a few falls in our club over trenches running along the road, one of which was nasty. And the trenches that cross the road can really hammer the sh1te out of your car.

smacl

outfox wrote: »

Council's should remove third class roads from their maintenance programmes, and use the money to bring regional roads up to scratch. If you chose to live in the arseh0le of nowhere up a third class road, tough. I say that as someone who lives up a third class road.

Personally, as a solo cyclist I try to take in as many quiet L-roads on my spins as possible. Very little traffic, great scenery and I use wider tyres so road condition isn't an issue. I would hate to see the loss of this part of our transport infrastructure which would occur relatively quickly without maintenance. Some of the most well loved cycling routes and mountain passes in this country follow L-roads.

Wildly Boaring

outfox wrote: »

That certainly makes sense, tigerboon, to allow settlement. But in the interim, some of the trenches can be messy. We've had a few falls in our club over trenches running along the road, one of which was nasty. And the trenches that cross the road can really hammer the sh1te out of your car.

Yep another problem with trenches is that it was always practice to seal the interface with the existing. The seal is just pitch poured on the joint. Nice and slippy on a bike

This case was an eye opener to the industry. It was on an N road which has a different reinstatement procedure to R and L roads. Has changed best practice.
https://www.irishtimes.com/news/crime-and-law/courts/high-court/cyclist-awarded-64-000-over-fall-that-left-him-seriously-injured-1.3858677

As it said earlier the only way I'd see the after care of spray and chip changing is under similar circumstances

magicbastarder

I had a near fall at 40km/h+ a year or two ago. Heading towards swords on the ashbourne - swords road, in the wet, I reached a section where the left most section of road, maybe 50cm wide, had been re laid. I suspect due to subsidence. It was the scenario in the article above - my front wheel slid on the tar poured between the old and new surfaces, which meant it slid left because of the camber of the road. Problem for me was that it slipped down onto the new surface which was probably a centimetre or two below the old one - and bear in mind my front wheel had already just been whipped to the left on me, i found myself desperately trying to steer to the right to rebalance, but my wheel couldn't mount that lip between the two surfaces, so was bouncing along it.
somehow i managed to stay upright, but it'd have been bloody sore if i'd come off.

outfox

smacl wrote: »

Personally, as a solo cyclist I try to take in as many quiet L-roads on my spins as possible. Very little traffic, great scenery and I use wider tyres so road condition isn't an issue. I would hate to see the loss of this part of our transport infrastructure which would occur relatively quickly without maintenance. Some of the most well loved cycling routes and mountain passes in this country follow L-roads.

Oh I agree that the backroads are spectacular, and a hugely untapped cycling resource in Ireland. But we have gravel bikes and MTBs for rougher roads, so I'm not sure if every back road needs regular resurfacing. There are third class boreens near me with grass up the middle that have better surfaces than nearby regional roads and local primary roads.