Post-IMF Road Design Standards

miles deas · 11-02-2011 2:47am #1

Hi,
This thread is aimed at posting ideas and examples for a new mid-sized road option. Its all about one possible "Do Something Else Option". The debate about if one is needed could start here but lets get some options first. I'll put some background in first if that helps:

So a capacity AADT of anywhere between 14,00 and 18,000 say.

here's what we have already:

Comparison%20UK%20Irish%20Single%20Carrigeway.png

Comparison%20Swedish%20Irish%202%2B1%20Cross-Sec.png

Comparison%20UK%20Irish%20Dual%20Carrigeway%20Cross-Sec.png

Here's the land take for off-line construction:

Any idea is worth a punt on-line, off-line, construction materials or methods. You name it, if its an idea post it. Can we aim for constructive criticism there are bound to be posters with limited experience of road design and pro's. So help those who need it get the most from their ideas critique not criticism.

miles deas · 11-02-2011 2:58am

If accidents tend to happen at the end of the 2 lane section of a 2+1 because people squeeze in a cheeky overtake why not have a speed camera or dummy camera toward the end of as many such sections as possible. Could the RSA work with the NRA to publicize any such dangers intermittently.

runway16 · 11-02-2011 3:26am

I've been following the last thread with interest Sir.

You did indeed have a point all along, but sadly you got mired with a few misunderstandings concerning road types, compounded by some dodgy information from others.

Now that those have been resolved, you have a very worthwhile argument, and it is indeed a debate worth having on how we keep some investment going in these more frugal times.

My own view - we still need the M20, Cork Northern Ring Road, The atlantic corridor as at least a 2+2, the N24 as a 2+2, and a the remaining small sections of motorway or type 1 DC that the NRA have planned and seem to be proceeding.

I'd also argue that either the N4 or M3 corridors need to be developed as at least 2+2 to serve the North west to ensure it has equivalent access.

Beyond that, we need to examine the sort of road type for the few remaining national primaries that will never justify a motorway, and indeed for the busier national secondaries.

miles deas · 11-02-2011 3:44am

Good point it doesn't stop it just changes there will always be areas of highest priority things may not change there. Its the ones in between that need thinking out of the box. If you have any ideas please share your thoughts. If your interested Sponge Bob mentioned. Sparse 2+1's. The accident rates on rural dual carriageway is about 3 x10 to the power 8 per km while 2+1 is 4 to the same power per Km. If some ideas come on how to address this the the sparse 2+1 might fly. From the other thread widening 40% of an existing road instead of 100% sounds worth investigation in these times.

Thanks, signing off now, night.

L1011 · 11-02-2011 9:01am

Any form of 2+1 means that one direction has no overtaking opportunities *at all* for a period of time. Seeing as we have slow moving traffic using national routes, this is the main reason that 2+1 is a failed road type and was removed from the standards list for new builds.

If you'd actually drive a bit, you'd see that 2+1 is a poor road type, and you'd also see that there is little difference between it and 2+2 in land take and carriageway width (due to 2+1 needing a larger hard strip and refuge areas on the single side, as well as much larger deceleration areas for junctions. 2+2 is a mid sized road.

Sections of 2+2 would not have this problem but would still suffer from the bunching problems familiar to anyone who ever drove the A1 to Belfast more than a couple of years ago - this at that time had patchy DC between the border and Hillsborough

dubhthach · 11-02-2011 9:07am

miles deas wrote: »

If accidents tend to happen at the end of the 2 lane section of a 2+1 because people squeeze in a cheeky overtake why not have a speed camera or dummy camera toward the end of as many such sections as possible. Could the RSA work with the NRA to publicize any such dangers intermittently.

This is indeed a problem, I know for example where the M11 narrows to single carriageway (Arklow gap) that there is always a mad dash up the overtake lane to try and squeeze in before the merge.

In general I do think we need more work from the RSA for example on 3 lane motorway with "middle lane hoggers". I wouldn't be surprised that alot of problems are due to the fact that there is no mandatory driver training in Ireland. In lot of European countries you have to do 20hours certified lessons before you can do the driving test.

Sponge Bob · 11-02-2011 9:30am

We should look at interspersing 2+2 and S2 on certain corridors, eg the N5 and N21 and N22. Reliable overtakling opportunities every N KM should be provided by 2+2

As regards driver behaviour

1. The end of a 2+2 should be merge only ( no overtaking) with enforcement.
2. "Move Over" laws together with laybys should be considered on National Primary S2 sections ....with enforcement.

corktina · 11-02-2011 9:48am

congrats on the new thread. Now that you have "gone native", can we expect a change of name to "kilometre deas"?:D

miles deas · 11-02-2011 11:24am

Kilometres Deas it is then. Regarding platooning of cars (all bunched up behind a front slower vehicle) on single carriageway sections of a 2+2-S2 alternating stretch. What would people consider acceptable is there any safety or economic data.?

Remeber 4 lanes may offer the best driver experience but economics is important too. I know your belief that 2+2 is the ultimate mid-sized road Mr MYOB, a few years ago it would be hard to argue with you. Now maybe the best value lies in accepting a degree less of service for a cheaper option. I'm not saying necessarily 2+1 I believe its only 10% cheaper, on average. But maybe Sponge Bob's 2+2-S2 alternating road or sparse 2+1 which has mainly SSC with intermittant stretches of new 2nd lane alternating.

Mr MYOB you do a lot of driving in your line of work have you seen any other examples of road lay-outs in your travels for this target area?

I'll put up a UK slide that shows opening year AADT ranges for some roads. I'm not pushing necessarily for WS2, cos I'm not. But more the traffic range I think is worth a focus upon:

DMRB_UK_Vol-5-Sec-1-Part3-TA4697%20Ch.2%20Graph.png

DMRB_UK_Vol-5-Sec-1-Part3-TA4697%20Ch.2%20Graph.png

regarding dubhthach's comment on mandatory driver training, I think your right. That sort of long sighted investment lasts a driver a lifetime with an annual return through that time. I bet if you ask the ESTC they'll give you a wealth of data of financial returns 100's of percent greater than the initial investment. But it will be hard to champion at the moment when we're 7th out of the EU 27 for safety. Still if the economics is there it would be hard to dismiss.

Where else are the safety problems on 2+1's? Run with it for a second Mr MYOB just want to work this thing through.

miles deas · 11-02-2011 11:37am

Just had a thought on Sponge's 2+2-S2 concept. If we had more automated traffic counters we could target the S2 to the less trafficked sections on a route. It would enable a more consistent LOS (level of Service - a measure of driver experience sudden braking or platooning of traffic in little slow moving clusters etc.). Even when the road switches to cheaper S2 single carriageway.

I'll keep putting the explanations in to keep this accessible to all. Sorry the experts amongst us. You never know where a good idea might come from so keep it accessible if you have the time.

Sponge Bob · 11-02-2011 1:01pm

miles deas wrote: »

Just had a thought on Sponge's 2+2-S2 concept. If we had more automated traffic counters we could target the S2 to the less trafficked sections on a route.

Exactly, instead of intermittently measuring traffic for a single scheme we do a "whole of route" analysis. In the example of the N5 there are rural sections eg east of Charlestown and west of Ballaghadereen that do not carry as much traffic as NEAR and AROUND those towns. The 2+2 stretches should generally bypass a town around where the heavier traffic is. One could nearly go for Type 2 SC on those stretches were it built offline but I am minded to build Type 1 SC de minimis on a route like the N5.

As regards S2 stretches and platooning I would point out that much platooning is caused by crap drivers and crap drivers will not pull onto hard shoulders. Therefore we need laybys at predictable intervals on those S2 stretches together with a move over law.

The move over law should generally state that where a car is not constantly driving at a MINIMUM 80% of the permissible speed limit on the stretch AND where more than 4 cars are held up by that front car THEN the driver of the front car MUST pull into the next drivethru layby and let those cars past after which they may pull out and proceed. In practice that means 80kph on a 100kph road.

That means we need proper laybys with good merges but only for 200m out of every 5km. It also means we need not build hard shoulders that nobody uses...especially those who should use them the most.

This all makes the user experience more predictable and therefore much safer but does not require WS2 type roads and their associated land take or an overabundance of 2+2. If you do find yourself bunched you know that the gobdaw in front will have to pull over within 5km.

It would be possible to implement a move over law by retrofitting laybys to existing WS2 and even S2 as well. It should certainly be piloted on one of the more adequate ones. However in most cases we have no option but to build a new offline road because the existing one cannot be upgraded properly.

miles deas · 11-02-2011 1:14pm

Fair point Sponge. I get frustrated by slow drivers that won't pull over. Do you know of any international examples of similar laws to 1) provide a president and 2) a possible template. Its not a necessity we can have the good ideas first. The sort of cautious drivers that do this are just the sort that would religiously follow the law with minimal enforcement needs. I'm no lawyer but airtight drafting of this law would possibly be unnecessary. Its very presence on the books would probably have a significant effect. I bet the RSA has some cool term for this phenomenon and some research to boot that it causes frustration in other drivers and dangerous overtaking and accidents. Getting that would add weight to the proposition.

Amtmann · 11-02-2011 1:34pm

I think you need to establish a list of routes scheduled for upgrades that you are happy to have as type 2 dual carriageway for the full length of the road, and then outline your compromise solution for other specific routes.

miles deas · 11-02-2011 1:50pm

Tremelo, I'm not so sure it might look presumptuous of me. I don't have knowledge of the whole network like some of you guys do. What I could do is lay that open for all to make comment on and then offer to summarize at the end of each week with a table with 1 column showing the route another 2 columns showing positive and negative posts for 2+2 upgrade for each route and another 2 columns for positive and negative comments on a smaller on-line development. What do you think?

miles deas · 11-02-2011 1:56pm

I have enough knowledge of one route to post on that. But I don't want it to become too route specific a thread. But it would add relevance and more specific useful contributions especialy if Sponge Bobs 2+2-S2 alternating route option flies. The problem is I have my true name on this and I don't want to trash the thread by seeming biased to one route or a solution. Maybe I need an alias.

Tech3 · 11-02-2011 2:01pm

Which road do you have in mind miles deas? I think we will allow the discussion of any route once it stays on this thread.

Sponge Bob · 11-02-2011 2:06pm

Well we only want to see a single route as an example. I picked the N5 because I know it. People do understand the difference between an EG and Outright Advocacy around here.

You may change your username if a mod nicely asks an admin, PM a suggested new one " Blacktopper " is available for ya

miles deas · 11-02-2011 2:07pm

N11/N25 Rosslare-Oilgate. I think it can be argued an on line option with upgrades as proposed by Sponge Bob could fly.

dubhthach · 11-02-2011 2:07pm

miles deas wrote: »

I have enough knowledge of one route to post on that. But I don't want it to become too route specific a thread. But it would add relevance and more specific useful contributions especialy if Sponge Bobs 2+2-S2 alternating route option flies. The problem is I have my true name on this and I don't want to trash the thread by seeming biased to one route or a solution. Maybe I need an alias.

I wouldn't be too worried about been seen as biased when it comes to route selection. In general we all tend to have our own little "biases" -- for example as a Galway man I want the Outer bypass etc.

The important thing in general is to put forward your argument to "the floor". There could be features of that route which are applicable/similiar to other ones.

miles deas · 11-02-2011 2:09pm

Can a mod. change my name please to "the Scarletpumpinickle" or something equally foolish then?

Amtmann · 11-02-2011 2:10pm

miles deas wrote: »

The problem is I have my true name on this and I don't want to trash the thread by seeming biased to one route or a solution. Maybe I need an alias.

miles deas wrote: »

Can a mod. change my name please to "the Scarletpumpinickle" or something equally foolish then?

We all know some routes better than others. I'm clueless about most of the N50s and 80s for instance, and I don't know much about the N12-N16 either.

If you aren't happy with having your real name appearing here, maybe you'd like to register a new Boards.ie account with another email address and choose something more anonymous, and then post under that. Your posts thusfar would remain as written by Miles Deas, but all new posts would be under the new name you pick. That would be no problem in this case, seen as how you are being very open about everything. Up to you entirely! None of us have the ability to change your username though, unless you actually subscribe to Boards.ie for a small fee, in which case the admins will do it for you. Otherwise, registering a new account would be the best solution for you.

But I do think it would be good to have a few specific routes named and discussed for your design ideas, just so people can better visualise the solution as well as spot potential problems, practical difficulties, etc.

Sponge Bob · 11-02-2011 2:30pm

miles deas wrote: »

N11/N25 Rosslare-Oilgate. I think it can be argued an on line option with upgrades as proposed by Sponge Bob could fly.

Dunno about that one

The Only Online possibility I see is that the Wexford Bypass could be made 2+2 with Offline S2 south and Offline 2+2 North to Enniscorthy.

The road further north has too many entrances for it to be online upgradeable...in my opinion and from memory.

But I await the case...agog! Try using OSI maps to illustrate a point rather than Google which has dreadful road maps. Here is one spot with different overlays selected according to the number at the end. Practise a tad.

http://maps.osi.ie/publicviewer/#V1,700586,628607,6,1
http://maps.osi.ie/publicviewer/#V1,700586,628607,6,2
http://maps.osi.ie/publicviewer/#V1,700586,628607,6,3
http://maps.osi.ie/publicviewer/#V1,700586,628607,6,4
http://maps.osi.ie/publicviewer/#V1,700586,628607,6,5
http://maps.osi.ie/publicviewer/#V1,700586,628607,6,6

Convert OSI to Long and Lat ( or vice versa) using

http://www.fieldenmaps.info/cconv/cconv_ie.html

Simply enter OSI x and y example above, ie 700586 628607 into Irish Transverse Mercator field and press convert

Yahoo maps are vastly superior for Irish Roads as they NOW exist.

eg

http://maps.yahoo.com/#mvt=m&lat=55.431618&lon=-7.241814&zoom=14

blacktopper · 11-02-2011 2:36pm

Good afternoon gentlemen. I would like to contribute to the lads comments regarding Rosslare-Oilgate's proposed scheme. I wonder if there are sufficient grounds to advocate 2+2 throughout. Such as the port itself, is it a sufficient driver. I would like to show the traffic growth between 2007-2010 right at the port NRA automated counter N25-1 on the proposed route and surrounding counters as my first piece of evidence showing the fall in traffic around the proposed route:

Traffic, particularly at the port is shrinking at an ever increasing rate. What conclusions do you draw?

blacktopper · 11-02-2011 2:39pm

Just got the above Sponge will have a go.

Sponge Bob · 11-02-2011 2:56pm

You may presume we all read this too

blacktopper · 11-02-2011 2:58pm

I presume some of you may even of had a hand in writing it.

Sponge Bob · 11-02-2011 3:03pm

We would also know about this and personally I would generally consider Jan and Dec 2010 to be weather related anomalies.

blacktopper · 11-02-2011 3:07pm

If we ignore the falling traffic but follow present NRA predicted growth as per appendix 6 we show traffic growth as per below:

NRA%20Forecast%20Traffic%20Rosslare%202011-40.png

NRA%20Forecast%20Traffic%20Rosslare%202011-40.png

We never get to the max capacity threshold of S2. This is what got me interested 6 months ago. What would your initial thoughts be if you were me?

munchkin_utd · 11-02-2011 3:10pm

Again to re-iterate, on long cross country journeys, a mere or 3 individual slow motorist, holing up entire swathes of traffic, can add hours to your journey.

i suggested an idea before that is cheap and maybe suited to the more frugal post IMF times. It occured to me after many many frustrating kilometres en route from North of Cavan to the far side of Cork City.

On the N3 between Cavan Town and the Kells ByPass, I was behind a reasonably quick truck doing mostly 80, which at the same time slowed to 60kph for the crack of it every so often. The road is good quality, but still hard to overtake as its also busy in the other direction. So on a quiet day you would tip along at 90/ 100kmh no bother with the exception of Virginia Town.

Anyhow, we both slowed at the roundabout at the Cavan/ Meath border, but afterwards where theres 2 lanes, I blasted by him within seconds (as trucks and pensioners driving clapped out fiats have VERY slow acceleration)

The same happened to me on the 2+1 heading out of Letterkenny. The 2 lanes AFTER the roundabout afforded me the chance to very quickly steam by slower traffic that I was behind since the town.

To compare, the 1km overtaking sections on the Mallow 2+1 are not long enough, as you are moving along at 80 or 90, so actually have very little time to overtake.

The essence and elegance of my idea is that by overtaking at a slower speed, you get the advantage of a better acceleration of car vs truck (/15year old fiat) and you are both travelling slower, so you have longer to overtake so more people can overtake.
AND its a localised solution, as opposed to the long stretches that otherwise would be built.

And going back to the Roslare-Oilgate section.
Heres heading away from the roundabout at the southernmost section of the Wexford bypass, where a car is stuck behind a horse trailer, which on all probability they have been behind for kilometres.
http://maps.google.de/maps?f=q&source=s_q&hl=en&geocode=FYCfHQMdfoye_yk9iHeEJxpoSDFAHjKXqccACg%3BFbXgHwMd2mCc_ynPaK1uwgNoSDHwlTGXqccACg&q=Rosslare+to+Oilgate&aq=&sll=51.151786,10.415039&sspn=15.571663,47.768555&ie=UTF8&ll=52.303231,-6.461377&spn=0,0.046649&z=15&saddr=Rosslare&daddr=Oilgate&layer=c&cbll=52.30322,-6.461389&panoid=R4e_v6VXZe1hFTSKQgHaxg&cbp=12,242.59,,0,14.19
You could say that the horse trailer pull in for the car behind.
With my solution, the car would be past the horse trailer already after leaving the roundabout!!

Another advantage is that the cars are NOT going at full tilt coming into/ exiting a roundabout. With the lower speeds the solution is cheaper than a normal 2+1 as you could even get away without a central barrier (making the solution in the case of existing roundabouts like the roslare bypass no more than the cost of re-painting lines !!)

Amtmann · 11-02-2011 3:40pm

And again, please DO NOT make AADT the sole determinant in your analyses. You must also consider the current road's alignment AND geometry, as well as the amount of private accesses along it. Private accesses include houses, farmyards, pubs and field gates. Then you must consider junctions, where regional and local roads meet the main road. AADT may be a lot lower than the maximum capacity, but when you factor in all of the above, you see that the road's viability and utility as a transport corridor is greatly diminished.

blacktopper · 11-02-2011 4:05pm

Fair point Tremelo, but do those junctions affect say collisions on the road? after all that's one of the important factors regarding junctions and say 15% of the economic benefits. If I trawl the older work I found this:

I get your point, but where would the BCR be if traffic is down and accidents were low to start with. Quid pro quo.

Post-IMF Road Design Standards

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