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Old August 4th, 2010, 01:51 AM   #1
Wallaroo
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Rebuilding emergency shoulders into a third lane?

I am thinking that full length emergency shoulders on motorways are unnessecary, and therefore should be rebuild into a third lane on the congested stretches. 3 lanes in each direction is a lot safer and gives a much better traffic flow too, as you propably know. A 30-40 meter long SOS emergency shoulder for every 500 or 1000 meters should be enough IMO.

obviously this is a lot cheaper than expanding with an extra lane + the shoulder, but the question is how much cheaper it would be?

for reference -motorway without shoulder

Last edited by Wallaroo; August 4th, 2010 at 03:51 AM.
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Old August 4th, 2010, 01:56 AM   #2
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Usually a shoulder is not wide enough to accommodate an extra lane. Moreover, if you want to achieve true safe high speed flows, you must have both a left and a right shoulder.
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Old August 4th, 2010, 02:24 AM   #3
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On part of the M42 in Birmingham the hard shoulder is used as an extra lane at busy times as part of the variable speed limit system - I think the Government policy (at least before the election) was to expand this to other motorways as a cheaper alternative to widening sections to 8 lanes

http://maps.google.co.uk/maps?hl=en&...35.71,,1,-9.42
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Old August 4th, 2010, 02:38 AM   #4
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same thing here in bologna. well, at the time google shot street view the lane was open

http://maps.google.com/?ie=UTF8&ll=4...11,238.05,,0,5
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Old August 4th, 2010, 03:14 AM   #5
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Quote:
Originally Posted by Suburbanist View Post
Usually a shoulder is not wide enough to accommodate an extra lane. Moreover, if you want to achieve true safe high speed flows, you must have both a left and a right shoulder.
in denmark where i live the shoulders are usually 2,5 meters wide, with 1 unpaved extra meter to the sides. the middle of the motorway is usually 3 meter, so if we repave the shoulder + the extra unpaved meter and take 1/2 meter from the middle, then we will have 3 x 3,5 meter wide lanes in each direction.

in germany the shoulders seems to be paved with asphalt and be at least 3 meters wide, so thats even easier
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Old August 4th, 2010, 09:52 AM   #6
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Unfortunately, this is becoming a common practise because it so much cheaper than actually widening the road. South of Stockholm the E4-motorway is being widened by replacing the median strip with a concrete barrier and using about of the emergency shoulder.

I've described this project in greater detail in the Swedish motorway thread.


Last edited by kanterberg; August 4th, 2010 at 10:04 AM.
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Old August 4th, 2010, 10:50 AM   #7
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It's a bad idea. Shoulders are not only for breakdowns, but also in case of accidents, so you have a place to stop without blocking all traffic. Additionally, shoulders need to be used in case of road works as driving lanes so you can maintain your number of lanes during roadworks, hence reducing congestion. Shoulders are also necessary to accommodate traffic on overloaded off-ramps. You can also use shoulders to avoid unexpected debris in the road.

No, structurally replacing shoulders with driving lanes is not a good idea.
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Old August 4th, 2010, 11:00 AM   #8
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If anyone has had a flat tire on a freeway with a small emergency lane it's a pretty awful experience.
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Old August 4th, 2010, 11:12 AM   #9
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It also depends on why it is done. I agree with Chris and FM, there are plenty of safety arguments to be made about an emergency shoulder.

However, there are times when this solution can be justified. In the Stockholm example above, there are plans to build a new motorway to the west of the current one. The only problem is this will take at least 10-15 years to plan, get all necessary permits, dealing with NIMBY’s etc. In the meantime, traffic is increasing on the current 2x2. It’s at 70 000 AADT today and expected to increase as the metropolitan area is growing rapidly. The Stockholm metro area is expected to grow by half a million people in the next 20-25 years.

In such a situation, rebuilding a motorway using the emergency shoulders and the median strip might not be such a bad idea. The alternative is having a 2x2 with an AADT of over 100 000 in ten years or so.
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Old August 4th, 2010, 11:29 AM   #10
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Quote:
Originally Posted by hofburg View Post
same thing here in bologna. well, at the time google shot street view the lane was open

http://maps.google.com/?ie=UTF8&ll=4...11,238.05,,0,5
http://www.autostrade.it/en/opere/a1...html?initPos=2



They even made the same thing in Mestre bypass (the old one, once with two lanes and the shoulder)



And they're going to build a dynamic lane in Milan on A4 urban stretch: in this case the widening will be from 3 to 4 lanes

The lanes are generally a bit more tight and max. speed allowed is low (80/90 km/h). A dynamic lane can be closed in case of emergency to become an emergency lane and let the emergency vehicles pass

This is how the signage works



-------------

I think this kind of system can be useful for little branches (10/20 km max) in densely urbanized territory where there is no space to widen the roadway.
In all the other cases better to add a new lane
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Old August 4th, 2010, 03:06 PM   #11
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Variable horizontal lane demarcation

Since we are discussing reversible lanes, running shoulders ans so, I have a question. Would it be feasible to have variable lane demarcation in such sectors with tightened (= more lanes than usual) lanes, running shoulders and so?

Running shoulders are usually activate by variable signaling like the one shown on the post above. However, it still means other lanes are shortened, thus maximum speed is reduced at all times.

I was thinking about a system of embedded "smart" lightening on the road pavement to "change" the demarcation of lanes according to demand (based on LED lights). During periods of lower traffic, those sectors would have fewer and wider lanes and shoulders at both sides, increasing speeds. During peak times, more lanes would be fitted in the same carriageway.

It would be just a matter of turning some light on (to mark the lanes) or black (to blend them with the asphalt), with some special sections with even more complex signaling to allow for "transition" when needed.
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Old August 4th, 2010, 05:53 PM   #12
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Converting an emergency lane into a driving lane might be handy in non-transit urban areas, but not on major motorways. They're planning to do this on Slovenian A1 between Ljubljana and Vrhnika. I searched for these plans again, but I couldn't find them, so I sincerely hope they let go of this ridiculous plan.
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Old August 4th, 2010, 10:41 PM   #13
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Quote:
Originally Posted by Suburbanist View Post
I was thinking about a system of embedded "smart" lightening on the road pavement to "change" the demarcation of lanes according to demand (based on LED lights). During periods of lower traffic, those sectors would have fewer and wider lanes and shoulders at both sides, increasing speeds. During peak times, more lanes would be fitted in the same carriageway.

It would be just a matter of turning some light on (to mark the lanes) or black (to blend them with the asphalt), with some special sections with even more complex signaling to allow for "transition" when needed.
OT: There are times when we have to live without lane markings entirely...

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Old August 5th, 2010, 08:00 PM   #14
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Actually, some of the most heavily used expressways in the densest cities of the World already don't have emergency shoulders : some NYC highways, Paris Périphérique, most (if not all) Tokyo expressways etc.

Since 2006 (date?) the emergency shoulder is also open to regular traffic during rush hours on a 3 kilometres stretch of A4 East of Paris, allegedly one of the busiest sections of expressway in Europe.

It is a clever idea in dense urban areas facing congestion, as long as the lanes are wide enough and the speed limit adapted (e.g. 80 km/h on the Périphérique, 90 km/h on the A4, compared to the 130 km/h on regular French motorways).
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Old August 6th, 2010, 10:59 AM   #15
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This has been done on one of Melbourne's freeways and also on the Westgate Bridge..... with an associated speed limit drop. Personally I think it is stupid, dangerous and is real good example of a do-nothing government looking for the cheapest and easiest "fix".
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Old August 7th, 2010, 09:02 PM   #16
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Quote:
Originally Posted by kanterberg View Post

Thats the way to go! It might have been even cheaper if they didnt mess with the median strip and took all of the shoulder instead, and then made short emergency shoulders for every 1 km. There are many stretches of italian motorways with this system, and it works perfectly IMO.
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