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Old September 15th, 2014, 11:04 PM   #321
sponge_bob
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A 16m 2+2 width is not in the least substandard at 100kph unless:

1. There are too many roundabouts inline or
2. The junction run in and run out ( RIRO or Right in Right out) lanes are too short.
3. The outer edge is not painted in reflective paint.

They are very safe and predictable otherwise except that they cannot take much beyond 30k AADT unless they are completely 100% rebuilt to Motorway and the curve geometry will often be too tight for safe 120kph Motorway running. Then again England and France have numbers of 80kph curves on their motorways where they cocked up the curve geometry on day one.

Ireland also has a 2+2 'Rural Motorway' standard with 3.5m lanes and most of the Irish Motorway Network by length is built to this standard save near cities. It is probably fine up to 40k AADT not that any sections are near that yet. The carriageway is 21.6m total inc the 60cm slipform concrete barrier. Above that design year AADT you need proper width 3.5m hard shoulders and a wider median ...in case.

Obviously the curves are 120kph rated too. In practice it is perfectly fine to drive it at 140kph, allowing for stiff crosswinds and water spray or fog of course where you should slow down to a more sensible speed.

http://nrastandards.nra.ie/road-desi...d565b/no_html1

But I would not go below 3.5m lane widths in Northern Europe save for 'urban' sections limited to 60-80kph max where I might consider 3.2m width lanes as safe. One must be mindful of side winds/storms and ice too.
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Old September 15th, 2014, 11:12 PM   #322
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Sweden was in a unique position that it had so many 11-13 meter wide roads which could be converted to 2+1 at minimal cost. I've read reports that some segments cost only a few € 100,000 per kilometer to convert (mainly restriping and adding a cable barrier).

How common are 2+1 roads with no barrier in Sweden? I don't recall having seen them. They are fairly common in Germany.
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Old September 15th, 2014, 11:20 PM   #323
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Quote:
Originally Posted by ChrisZwolle View Post
How common are 2+1 roads with no barrier in Sweden? I don't recall having seen them. They are fairly common in Germany.
They are a 1980s era retrofit standard in Sweden. France and Germany built a lot of 2+1 on their national road network in the 1950s and 1960s before they gave up and built a Motorway alongside in the end.

I doubt if France and Germany built (or retofitted in) any rural 100kph (110kph) 2+1 after 1980.

Both Germany and Sweden liked wide straight 1+1 as they planned heavily on dispersing their substantial air forces to them in the event of war pre 1991.
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Old September 15th, 2014, 11:27 PM   #324
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First class road I/48 in Czech Republic is a 16m wide grade-separated road designed as a two-lane road with wide shoulders, but painted as a four-lane road. The speed limit is 90km/h and it carries 12000-20000 VPD. I have to say, that on weekdays at peak hours it is a very unpleasant road to drive on with many HGV etc.
On the other hand, when the traffic volume is lower(weekends, early mornings, ...), it isn't that bad, especially the part with cable barrier.

Unseparated part: http://goo.gl/maps/xMQC0
Part separated by a cable barrier: http://goo.gl/maps/widbZ
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Old September 15th, 2014, 11:44 PM   #325
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Quote:
Originally Posted by patakcze View Post
First class road I/48 in Czech Republic is a 16m wide grade-separated road designed as a two-lane road with wide shoulders, but painted as a four-lane road. The speed limit is 90km/h and it carries 12000-20000 VPD. I have to say, that on weekdays at peak hours it is a very unpleasant road to drive on with many HGV etc.
I think the unseparated part is a tad less than 16m and the geometry (curves) is tighter than Ireland and Sweden would allow.

The Irish and Swedish ones are straighter than that which allows 100kph.
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Old September 15th, 2014, 11:57 PM   #326
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A short 2+1 stretch in San Marino, driving from Acquaviva to San Marino city.
September 2014.

1.


2.


3.


4.
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Old September 16th, 2014, 12:01 AM   #327
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Quote:
Originally Posted by sponge_bob View Post
I think the unseparated part is a tad less than 16m and the geometry (curves) is tighter than Ireland and Sweden would allow.

The Irish and Swedish ones are straighter than that which allows 100kph.

Whooops, the road is actually built in two categories:
http://goo.gl/maps/VpwTv S15,0/100 - 15m wide, designated speed 100km/h, no barrier
http://goo.gl/maps/5oRn7 S15,0/100 - 15m wide, designated speed 100km/h, cable barrier
http://goo.gl/maps/1wloH S16,5/100 - 16,5m wide, designated speed 100km/h, no barrier
Anyway, the part with a cable barrier could easily have a speed limit of 110.
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Old September 16th, 2014, 12:11 AM   #328
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Quote:
Originally Posted by patakcze View Post
Whooops, the road is actually built in two categories:
http://goo.gl/maps/VpwTv S15,0/100 - 15m wide, designated speed 100km/h, no barrier
Anyway, the part with a cable barrier could easily have a speed limit of 110.
Ahhh. I thought it was less than 16m looking at it.

The real problem is with the continous curves you encounter.

You feel yourself 'pushed' out or in all the time and OUT means against a car travelling at a relative 180kph less than 1m away from you. That 1m of median and the barrier makes it 'feel' more comfortable and if the road was straighter it would feel more comfortable again. Tell the Czech lads to read the Irish and Swedish and Finnish standards _properly_ next time to see how it is done.
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Old September 16th, 2014, 12:33 AM   #329
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Well, the whole I/48 is constantly being reconstructed to an expressway in category R25,5/120. However, I don't really think that it's necessary, especially in the parts with AADT <15000. Adding a cable barrier and a little widening to 16,5m must be enough. But that's my opinion.
By the way, the narrowest four-lane expressway than can be built today in CZ is R21,5/100 with a maximum speed of 110 and left lane just 3,25m wide. And there is no category for 2+1 roads and I don't really get why, because I think that would be a perfect solution for newly built roads with AADT <10000.
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Old September 16th, 2014, 12:45 AM   #330
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Quote:
Originally Posted by patakcze View Post
Well, the whole I/48 is constantly being reconstructed to an expressway in category R25,5/120. However, I don't really think that it's necessary, especially in the parts with AADT <15000. Adding a cable barrier and a little widening to 16,5m must be enough. But that's my opinion.
Well 16m at least but the road may still be a 90kph after that owing to the curviness.

Quote:
By the way, the narrowest four-lane expressway than can be built today in CZ is R21,5/100 with a maximum speed of 110 and left lane just 3,25m wide.
Considering Ireland can get a full 120kph motorway into 21.6m you must be doing something a bit odd there.....oh!!! and NO

Quote:
And there is no category for 2+1 roads and I don't really get why, because I think that would be a perfect solution for newly built roads with AADT <10000.
Only in urban areas, too many crashes at the end of the 2 bits if you build them in rural areas apart from climbing lanes on mountains. Developed countries should not build 2+1 roads any more, too dangerous. Even in urban areas the middle lane should be a tidal flow lane to my mind not a 'real' 2+1

Build 1+1 or 2+2 and thats it or if you must 2+2 > Roundabout > 1+1 > Roundabout > 2+2 etc etc. And no hard shoulder on non motorways, just a layby area every 10km or so.
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Old September 16th, 2014, 02:51 AM   #331
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Quote:
Originally Posted by ChrisZwolle View Post
How common are 2+1 roads with no barrier in Sweden? I don't recall having seen them. They are fairly common in Germany.
There are a few. Mostly climbing lanes though.
http://goo.gl/maps/oduRR and http://goo.gl/maps/x91I7 (both same stretch, built in early 90s). There's also a newly built bypass here, which is 1+1 and 2+1 without barriers, but I can't find any images of it.
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Old September 16th, 2014, 03:23 AM   #332
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Old September 19th, 2014, 03:26 PM   #333
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This 13 m wide road in Poland (DK22) will be converted to 2+1

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Old September 19th, 2014, 04:33 PM   #334
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This is the standard cross-section for 2+1 roads in Estonia:


Currently there are no 2+1 roads in Estonia but the first section should be built in a couple of years.
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Old September 20th, 2014, 02:34 PM   #335
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This is the standard cross-section for 2+1 roads in Estonia:


Currently there are no 2+1 roads in Estonia but the first section should be built in a couple of years.

15m. When you could get a 2+2 into 16m.

Hopefully Estonia will ditch that standard and build full 2+2 instead. Much safer and more futureproof.
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Old September 20th, 2014, 03:12 PM   #336
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If you would incorporate the Estonian design standards of 2+1 into four lanes, the road width would be around 17.5 meters wide.
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Old September 20th, 2014, 03:39 PM   #337
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Go for 3.5+3.5 or 3.4+3.6 and no 1.0m edge strip either side and you get a perfectly good 2+2 into 16m.

As Estonia is flat there is no need for climbing lanes on 1+1 which is the only possible use for that standard in my opinion.
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Old September 20th, 2014, 04:00 PM   #338
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Quote:
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Go for 3.5+3.5 or 3.4+3.6 and no 1.0m edge strip either side and you get a perfectly good 2+2 into 16m.
By 'perfectly good', you mean 'heavily substandard'. You can't eliminate all safety features and then call it a 'perfectly good road'.
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Old September 20th, 2014, 04:30 PM   #339
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Quote:
Originally Posted by sponge_bob View Post
15m. When you could get a 2+2 into 16m.

Hopefully Estonia will ditch that standard and build full 2+2 instead. Much safer and more futureproof.
The difference between 2+1 and 2x2 is not one extra lane. It's limited access, collector roads, interchanges etc - that´s why it's a lot cheaper to build 2+1.

Mind you, the planned 2+1 roads currently have an AADT of around 7,000 which is way too little to justify a dual carriageway.

BTW, 15m includes the 50cm wide gravel shoulders on both sides. Without them it's 14m, perfectly fine for a 2+1 road IMO.
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Old September 20th, 2014, 07:46 PM   #340
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Quote:
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Go for 3.5+3.5 or 3.4+3.6 and no 1.0m edge strip either side and you get a perfectly good 2+2 into 16m.

As Estonia is flat there is no need for climbing lanes on 1+1 which is the only possible use for that standard in my opinion.
What narrow lanes and no edges, what crappy road to drive on. The extra cost is marginal! Should never have lanes narrower than 3,75 m and constrained shoulder unless there is a real reason (existing viaducts or dense urban area...)
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