RE: 50 limits by the back door: PH Blog
Discussion
fuelracer496 said:
Engineer792 said:
At the risk of stating the obvious, a large proportion of car traffic already does regularly travel at speeds of 80-90mph, and has done so for decades, with little or no evidence of 'crossover carnage'
The tests may only be approved for cars up to 70mph, but the fact is that if the barriers can physically withstand heavy vehicle impacts then they can certainly withstand car impacts at much higher speeds than 70mph.
The point is, simply changing the test criteria would likely 'future proof the system' in the vast majority of cases without having to dig the whole thing up
A barrier's strength is directly related to the pullout force of the foundation it's installed in. In the case of bridge parapets (bridges being my field of work) the pullout strength of a parapet base plate is limited by the deck edge beam. In the 1970's when the motorway bridges were designed, they were built based on a taking a parapet system with a 70mph limit. When the parapet is stiffened (post centres reduced in most cases), the force is transmitted into the edge beam because the barrier isn't absorbing the impact and pulling the vehicle in, avoiding it ricocheting back into traffic.The tests may only be approved for cars up to 70mph, but the fact is that if the barriers can physically withstand heavy vehicle impacts then they can certainly withstand car impacts at much higher speeds than 70mph.
The point is, simply changing the test criteria would likely 'future proof the system' in the vast majority of cases without having to dig the whole thing up
Edited by Engineer792 on Saturday 1st April 11:55
You'd find that a high containment barrier installed on a 70's era edge beam would fail under impact because it would shear clean off the deck. To strengthen bridge decks up and down the land isn't an option, not just because of cost but because of the room it takes up and disruption to road users. You'd end up needing to avoid trafficking the deck on one carriageway during the works as it's likely the cantilever section of the deck (the section between the outer steel edge girder / box girder and the parapet edge beam) would need to be replaced. That typically wipes out the hard shoulder and lane 1 from use, so once your works zone and safety zone are in place you're reduced to potentially single lane running as lane 2 would be on the narrow side and has to be used as a HGV lane during works.
Engineer792 said:
It's not clear whether you're talking about 70mph car impacts or 70mph lorry impacts
The speed limit currently in place dictates the testing and approvals in place for the barrier's use. In the case of cars, it's 70mph, and as you know, in the case of goods vehicles exceeding 7.5t it's 60mph. In either case, if you increase the speed limit to allow the racing drivers to get to their destination quicker, there's a lot of work involved in upgrading structures to absorb the increased load placed on them from using stiffer barrier systems.If the point you're implying is regarding HGV's exceeding the speed limit by way of limiters being removed etc, that's an issue you need to take up with Highways England, or perhaps the police. As managing agent for them, we're tasked with keeping the network in shape to cater for those who adhere to speed limits, not those who decide speed limits do not apply to them. There are laws, regulations and standards that are to be worked to - it's not just made up for the fun of it (as some would have you believe).
If you consider unrestricted stretches of autobahn as being evidence of none of this applying or being relevant - when you have an RTC on those stretches of road, and it's found that excess speed was partly or fully the cause i.e. above the speed limit for regulated stretches, you often find insurance companies will not pay out and claims made against the highway authority (often along the lines of "why wasn't I protected when I had my crash") will go against the driver.
Hope that helps clear some of it up, I don't have much else to add - maybe we'll back again next year for another article about how awful a job we do
fuelracer496 said:
As managing agent for them, we're tasked with keeping the network in shape to cater for those who adhere to speed limits, not those who decide speed limits do not apply to them. There are laws, regulations and standards that are to be worked to - it's not just made up for the fun of it (as some would have you believe).
yes yes yes and we all know what the speed limit guidance says to make sure of thatSo setting aside those that are ok, when 50s are installed or appear outside of those rules - what should happen?
Does the computer receive a fine?
fuelracer496 said:
The speed limit currently in place dictates the testing and approvals in place for the barrier's use. In the case of cars, it's 70mph, and as you know, in the case of goods vehicles exceeding 7.5t it's 60mph. In either case, if you increase the speed limit to allow the racing drivers to get to their destination quicker, there's a lot of work involved in upgrading structures to absorb the increased load placed on them from using stiffer barrier systems.
If the point you're implying is regarding HGV's exceeding the speed limit by way of limiters being removed etc, that's an issue you need to take up with Highways England, or perhaps the police. As managing agent for them, we're tasked with keeping the network in shape to cater for those who adhere to speed limits, not those who decide speed limits do not apply to them. There are laws, regulations and standards that are to be worked to - it's not just made up for the fun of it (as some would have you believe).
If you consider unrestricted stretches of autobahn as being evidence of none of this applying or being relevant - when you have an RTC on those stretches of road, and it's found that excess speed was partly or fully the cause i.e. above the speed limit for regulated stretches, you often find insurance companies will not pay out and claims made against the highway authority (often along the lines of "why wasn't I protected when I had my crash") will go against the driver.
Hope that helps clear some of it up, I don't have much else to add - maybe we'll back again next year for another article about how awful a job we do
I think the point was that if the barrier can withstand a truck/coach at 60mph it should withstand a car at 80mph (for example).If the point you're implying is regarding HGV's exceeding the speed limit by way of limiters being removed etc, that's an issue you need to take up with Highways England, or perhaps the police. As managing agent for them, we're tasked with keeping the network in shape to cater for those who adhere to speed limits, not those who decide speed limits do not apply to them. There are laws, regulations and standards that are to be worked to - it's not just made up for the fun of it (as some would have you believe).
If you consider unrestricted stretches of autobahn as being evidence of none of this applying or being relevant - when you have an RTC on those stretches of road, and it's found that excess speed was partly or fully the cause i.e. above the speed limit for regulated stretches, you often find insurance companies will not pay out and claims made against the highway authority (often along the lines of "why wasn't I protected when I had my crash") will go against the driver.
Hope that helps clear some of it up, I don't have much else to add - maybe we'll back again next year for another article about how awful a job we do
fuelracer496 said:
Engineer792 said:
It's not clear whether you're talking about 70mph car impacts or 70mph lorry impacts
The speed limit currently in place dictates the testing and approvals in place for the barrier's use. In the case of cars, it's 70mph, and as you know, in the case of goods vehicles exceeding 7.5t it's 60mph. In either case, if you increase the speed limit to allow the racing drivers to get to their destination quicker, there's a lot of work involved in upgrading structures to absorb the increased load placed on them from using stiffer barrier systems.If the point you're implying is regarding HGV's exceeding the speed limit by way of limiters being removed etc, that's an issue you need to take up with Highways England, or perhaps the police. As managing agent for them, we're tasked with keeping the network in shape to cater for those who adhere to speed limits, not those who decide speed limits do not apply to them. There are laws, regulations and standards that are to be worked to - it's not just made up for the fun of it (as some would have you believe).
If you consider unrestricted stretches of autobahn as being evidence of none of this applying or being relevant - when you have an RTC on those stretches of road, and it's found that excess speed was partly or fully the cause i.e. above the speed limit for regulated stretches, you often find insurance companies will not pay out and claims made against the highway authority (often along the lines of "why wasn't I protected when I had my crash") will go against the driver.
Hope that helps clear some of it up, I don't have much else to add - maybe we'll back again next year for another article about how awful a job we do
I'm trying to have an impartial discussion here but, going by your language here, it's clear that you don't - which is a pity, but hey-ho!
It's instructive to run a little bit of o level physics against the idea that bridges aren't strong enough to handle higher speed impacts.
Allowing cars to drive at 90 raises the impact energy by approximately 100%. But that is still an order of magnitude less than the energy of a 44 tonne truck at 60. So if our bridges can't handle cars at 90, we should be seeing lorries fly through barriers all the time.
Allowing cars to drive at 90 raises the impact energy by approximately 100%. But that is still an order of magnitude less than the energy of a 44 tonne truck at 60. So if our bridges can't handle cars at 90, we should be seeing lorries fly through barriers all the time.
Engineer792 said:
My point is that if a barrier can't withstand an impact from a car at over 70mph then it's extremely unlikely that it will survive an impact with a 44-tonner doing 56mph.
I'm trying to have an impartial discussion here but, going by your language here, it's clear that you don't - which is a pity, but hey-ho!
I'm trying to have an impartial discussion here but, going by your language here, it's clear that you don't - which is a pity, but hey-ho!
it does seem to be an obeying orders mindset.Kenny Powers said:
saaby93 said:
Some of the threads off topic but do you mean the 50s that appear for no apparent reason?
Do you have amnesia? 
Loads of people have posted about the 50s that appear for no apparent reason
Some have said in roadworks it's due to safety of workforce, when in the hours we're talking about there is no workforce and its not clear it improves safety
Someone else said it was for the safety of the general public, when it gain it wasnt clear that the 50s send the risk analysis the right way
Then there's the 50s that appear when nothings happened, which someone said was due to the way the speed monitors detect something moving slowly and think there must be a problem when there isnt
Does that sound like something's not quite right
Finally there are what seem to be the few occurrences where it does work as it should eg at the M5 M6 junction at busy times.
Is that selective enough
fuelracer496 said:
The Moose said:
From where I sit, the solutions are just a sticky plaster over a gunshot wound.
You say very definitely that you're not doing several things that really should be done.
Infrastructure is vital and if that infrastructure, or assets as you refer to them, aren't improved, updated upon and increased then the country will continue to decline.
To address the questions about why the 50 limits are in place even when motorways aren't being worked on at evenings and weekends well my question is why can't those roads be worked on over weekends and evenings. There are plenty of countries around the world where roadworks of major routes (and some less major) are done 24/7 until complete.
I don't disagree with you, those who work in the industry share the same feelings - we produce portfolios that are handed to the client for future years work to agree funding. The funding at source is from central government - if that doesn't filter down to the level where the managing agent can crack on and get stuff done, there's little that can be done. The proposed works are based on routine maintenance, where items are updated due to time (wear & tear, expired elements etc), or premature failure / defects that we try to resolve before they become more severe and increase the time and cost.You say very definitely that you're not doing several things that really should be done.
Infrastructure is vital and if that infrastructure, or assets as you refer to them, aren't improved, updated upon and increased then the country will continue to decline.
To address the questions about why the 50 limits are in place even when motorways aren't being worked on at evenings and weekends well my question is why can't those roads be worked on over weekends and evenings. There are plenty of countries around the world where roadworks of major routes (and some less major) are done 24/7 until complete.
Regarding 24/7 working, we do when we can but certainly in the case of bridge works, there's sequencing and phasing issues that sometimes prohibit what can be done - as an example, concrete works require a minimum 5 days of curing before shutters can be removed. During that time, there's little that can be progressed elsewhere as the next action would be waterproofing but until the shutters are gone and cube tests have come back as sufficient, this cannot be undertakem. While additives can help speed up the curing time, you often find that the end concrete strength is too strong and no longer works well with the existing concrete grade - the key thing here being that repairs need to be a like for like in terms of compressive strength.
We've trialed putting up signage for road users saying "concrete setting" for this very reason as the travelling public might see no work force present at that moment in time.
I can't speak for anyone else, but I'm not saying you're doing a s
t job (unless you're Chris Grayling) - more that the system is broken and needs serious attention. Again, I can't speak for anyone else, but I certainly appreciate you explaining the situation from the other side of the dot-matrix signs.I' m afraid my knowledge of concrete road repairs doesn't extend as far as yours obviously does, however I'd hazard a guess that through the sections of the (say) M4 where there were roadworks for ages (don't know if they are still there) where people are working during the day but not at night/weekends is nothing to do with concrete curing times. I also refuse to believe that every set of road works where there are no workers is due to concrete curing.
Between Christmas and New Year I has to head up into the North - fantastic sporting day in the country you see. At somewhere along my route (I have a feeling around the M1/M18 section) there were signs showing 40/50mph from memory - doing the speed limit dance as seems to be the way. It was unsafe to do the posted speed (due to the speed differential between other traffic and myself) and with no hazard I just pushed on as if it were a NSL. Received a letter in the post telling me that I'd been caught however the local constabulary were kindly not going to pursue it this time.
I'm afraid the system is broken (whether you like it or not) and needs carefully looking at. There aren't many countries in the world that would put up with this s
t!fuelracer496 said:
big_rob_sydney said:
You do realise that "vast majority" does not mean 100%, right?
In the cases where it is not, which was my point that you are deliberately avoiding, what is the answer? This is the third time I've asked the question, and frankly getting exasperated by a deliberately twisted answer.
Is it right to tell people essentially "watch out for our boys working", when they're not actually working?
Rob, reduced speed limits are in place for the duration of works regardless of whether the work force are present at the time - this was covered in a previous thread relating to the same sort of article, and also by myself in a previous post in this thread when asked about why speed limits remain in place in areas of cluster scheme TM. This is a requirement of chapter 8 but also sits under TD/27 05 which governs speed limits relating to running lane widths.In the cases where it is not, which was my point that you are deliberately avoiding, what is the answer? This is the third time I've asked the question, and frankly getting exasperated by a deliberately twisted answer.
Is it right to tell people essentially "watch out for our boys working", when they're not actually working?
As mentioned already, traffic management is not installed and removed on a daily basis - it's too time consuming and poses a safety risk for both the workforce and road users. For that reason, the reduced speed limit is enforced for the period the TM is on. I appreciate you believe the speed limit is there for the protection of the work force, and yes, that's part of it, but it's not the sole reason for it - as important is the safety of the travelling public and legally we cannot implement traffic management (be it lane closures or lane width reductions) without reducing the speed limit.
A significant amount of time is spent repairing TM (cones, temporary barriers etc) where drivers have had an RTC in the works, despite the reduced speed limit. I imagine this does little to satisfy your query but it may go some way to explaining some of the background.
Attilauk said:
big_rob_sydney said:
You do realise that "vast majority" does not mean 100%, right?
In the cases where it is not, which was my point that you are deliberately avoiding, what is the answer? This is the third time I've asked the question, and frankly getting exasperated by a deliberately twisted answer.
Is it right to tell people essentially "watch out for our boys working", when they're not actually working?
I'm not deliberately avoiding anything, you are not reading my responses properly! WE DO NOT PUT 50MPH SPEED LIMITS OUT IN ROADWORKS ON MOTORWAYS WHERE THERE IS NO RISK TO THE GENERAL PUBLICIn the cases where it is not, which was my point that you are deliberately avoiding, what is the answer? This is the third time I've asked the question, and frankly getting exasperated by a deliberately twisted answer.
Is it right to tell people essentially "watch out for our boys working", when they're not actually working?
Is that clear enough? I stated that you can find the guidelines in Chapter 8, did you look for them? There is no deliberate twisting, I said vast majority as there are other reasons why we may use restricted speed limits (again all in Chapter 8) i.e. contraflow or long term lane closure, however in THE VAST MAJORITY of times in long term works we use narrow lanes as it does not reduce traffic capacity on the road. I run roadworks for a living, I have NEVER seen a restricted speed limit in roadworks on the motorway without a valid reason, just because you can't see or understand that reason doesn't mean it doesn't exist!
Installation and removal of Traffic Management is a time consuming and expensive process, it also puts the men who install it at risk. To remove TM for the weekends just so you can go a little bit quicker would be a massive waste of time, money and resources. Also it would mean that any works that were being carried out would have to be protected at the end of the week so as to not pose a risk to travelling public, again this would waste time, money and resources and in a number of cases this is simply not possible.
As I stated earlier (on a number of occasions now) if its 50 it is because it is deemed a risk to the general public, to relax the speed limits knowing that it would put people at extra risk is not a decision that any project manager would make...
king hard / costly to take down signs saying people are working, when they're not actually working, because of reasons X, Y, and Z.Now, excuse me for pointing this out, but you have the speed limits that are electronically controlled. These can be swapped any time remotely. There is no barrier to someone swapping the speed limit, other than a will to do it. And funnily enough, there are cameras, which lo and behold, are also clued to the speed limit. And wouldnt you know it, they too are controlled electronically...
So we fundamentally come back to the point that its not being done, because people dont want to do it. Well and good to fall back on a bureaucrats pinhead decision, and to demonise drivers (you know, the people for whom the asset has actually been created for in the first place, and who pay for the system through exorbitant direct and indirect taxes. Remember us?) for wanting a more efficient paid-for service. Outrageous that we should want such return on our investment, isnt it?
Mandown46 said:
Big Rob, I feel like I've completely lost the train of that part of the discussion
What is it you would actually want to see happen? within what is reasonable of course (we all have our dream scenarios)
Without wanting to answer for him, howabout a system that actually WORKS as advertised. Smart motorways are currently anything but - they were implemented (at great cost and disruption, just ask anyone who's had to suffer the M1 or M5 in the last few years) under a great headline but it would appear without sufficient planning on how they would work in practice.What is it you would actually want to see happen? within what is reasonable of course (we all have our dream scenarios)
- If the software algorithms can get glitched by a slow-moving vehicle, improve the algorithms. That's eminently doable, esp. given the advances in heuristic software over the last few years.
- If there are insufficient people to man it, why wasn't this thought of and budgeted-in before it was kicked-off? And how about it IS resourced appropriately?!?
- If there's a different issue (that I've missed in this thread), why isn't it gamed-out and solved.
Problem-solving is an innate human skill...we're very good at it (well, some of us...presumably those not in government employ). This is a problem that the HA (and wider gov't?) has created and now doesn't actually seem fussed about solving. And it IS a problem, as the whole system, from initial r'works through to current operation, has done little to improve matters for drivers - if anything it's increased stress levels*.
* Ignore those of us who care about our driving enough to post on here - how about those who don't pay as much attention but up-to-now have got by driving OK - a colleague of my wife (who hasn't had an accident in years and has a clean licence) scared herself silly on the M1 last week because she thought she'd missed a gantry sign with a lower speed limit - she was driving at twilight, talking to my wife in the pass. seat, and then realised the next gantry up said 50 not the 60 they'd seen previously and couldn't consciously remember what the previous one said. According to my wife the traffic wasn't a problem and the gantries shouldn't have been on. Colleague is now worrying about receiving an NIP in the post...she's one of these middle class people who fears the law and would be mortified to be in trouble!
Without the gantries and their constantly yo-yo'ing limits, she'd have been absolutely fine. Things like this are bit-by-bit making our lives that little bit less tolerable, all (apparently/allegedly) in the name of control-freakery.
I hate to be contrary, but this particular section now appears to be working really well. No more stationary traffic around junctions etc... The other night there was debris in the road, signs progressively stepped down to 40 then straight back to NSL afterwards. Clear at night, and looking at the speed some cars were flying through the cameras they don't appear to be on unless the gantry is on.
It's quite weird not doing 30mph on my commute.
It's quite weird not doing 30mph on my commute.
saaby93 said:
Mandown46 said:
Despite popular opion, Smart motorways do increase traffic flow,
Methinks that should be Smart Motorways can increase traffic flowand you can see an example at busy times at the M6 M6 junction
At other times and in other places theyre patently not being used smartly and if those instances outweigh the places theyre working its giving the whole thing a bad name. Stupid motorways or motorways that smart
Edited by rampageturke on Tuesday 4th April 11:40
rampageturke said:
The main problem I see with smart motorways is they keep putting them in and telling nobody how they work. So people just see a lower 50 limit for what they think is absolutely nothing, then start seeing red like a bull and continue to do 70 then hit the congestion and complain when they don't work.
Do you know how they work, I mean really know?Gassing Station | General Gassing | Top of Page | What's New | My Stuff