Basics of Concrete Barriers (2000)
highways.dot.gov
highways.dot.gov
I was trucking up 44 at a fairly moderate pace (I'm not a big speeder) around a curve when there was suddenly a car in my lane, so I jerked the wheel to the right lane ... where there was another car, I twitch back to the other lane and begin, well, hydroplaning or whatever it is when you have just a touch of rain to bring up the oil from the road. Brakes were not effective and I was headed right for the highway divider at somewhere between forty to fifty miles per hour, at a forty-five degree angle. In this flimsy little car, that corner impact is going to hit me pretty hard.
That's when I looked at the little slope at the base of the highway dividers and reasoned that if I could get my car parallel to the divider, the impact would be taken on the left wheels and the left side of the suspension, areas designed to bear some weight from that particular direction already. I managed to get the car aligned by tweaking the wheel direction, hit, slid for about ten or fifteen feet. I was so nearly perfect to parallel that I only lost the rubber covering to about an inch of bumper. Ended up replacing the tires a few weeks later just out of an abundance of caution, but otherwise fine.
(It turned out that there was a big wreck up around the curve and various drivers had decided to just sort of stop where they were, hence my surprise obstacles)
>> fairly moderate pace (I'm not a big speeder)
But you were speeding, right? On a wet roadway with what sounds like poor visibility.
You should not drive at an unsafe speed, even though many drivers will do so especially when it's beneath legal limits. If you're losing steering authority, you either are going too fast, or you're somewhere you shouldn't be driving at all. The car is intended to operate with your steering wheel controlling where it goes, when that's not working you've stepped outside the intended bounds of operation.
Like I said, glad you're OK. Glad the barrier saved your life / reduced the damage. These barriers are a last resort. Terrifying to read just how many stories there are in this thread of people relying on them.
Better than barriers I would think is more driver training, higher standards for licensure, and more alternatives to driving. Safest way to travel is not in a personal car operated by an amateur.
In situations like that you can try to regain traction by making sure the wheels are pointing at the same direction you are traveling, not being on the brakes, etc. Practice on snow or ice in a safe environment. I'm not that great at this myself but I have recovered traction in a handful of real life snow/ice scenarios... Go-karting can also develop some skill/feel for this. You can also take lessons...
In my part of Europe (Slovenia) they now make you take a “safety driving” course within 2 years of getting your license. Skid plates, hydroplaning, all the fun stuff.
My sister got to do it. I missed the fun by a few years and instead practiced with lots of late night drifting fun on fresh snow (don’t tell mom :P)
I loved the skid plates — for those who don't know: this is basically a "moving floor" that yerks your rear wheels randomly left or right when you drive over it. This happens right before a wet section of track and depending on the speed you have while going over it recovering can be quite a challenge.
My car did not have ABS, so I had a lot of fun doing this.
Thank you for this explanation! There is a completely different kind of device called a "skid plate" in the context of 4x4 off-road driving, so I was imagining some gnarly things must be happening in this "safety driving" course!
That school principal was cool in a lot of ways like that. He'd never keep his job these days.
As a tip for others: If you ever encounter hydroplaning make sure not to keep your steering wheel straight (or at least: know why you are doing what you are doing) and step off the gas pedal.
In hydroplaning your wheels don't have contact with the road surface, so turning the wheel won't do shit. But as you loose momentum your wheels will regain contact appruptly again at some point. At that point it really matters how your front wheels are oriented when you do so.
If your front wheels point hard left and there is a dry part of the street you will be yerked directly into oncoming traffic for example.
remove the "not".
> (or at least: know why you are doing what you are doing)
Remove that too, it's unnecessary.
https://interestingengineering.com/innovation/this-new-korea...
Purely from a safety standpoint, outright prohibiting bicycle traffic on motorized roads would be a massive improvement at the expense of inconveniencing a small minority of people (while improving the convenience for everyone else). I'm kind of surprised more states haven't done it yet. Failing that, it's probably better to also use guardrails to physically separate the bike lanes from the motor lanes, which is yet another use-case for improved guardrails.
> In Zimbabwe, jaywalking is illegal, as per the traffic laws gazetted in 2013 by the Ministry of Transport and Infrastructure Development.
> In recent years, jaywalking has become more strictly controlled in China as car traffic increased. Police have tested facial recognition to identify jaywalkers.
Italy:
> Pedestrians are allowed to cross a street without any recognised crossing point only if there are no zebra crossings within a range of 100 m
To me this sounds like the equivalent of permanently shutting down a public park because it's infested with disease carrying rats rather than trying to get rid of the rats.
Wasn't this the same kind of argument we used in the past to justify slavery?
In that case perhaps we could compare the number of drivers in the United States with the global population and then talk about the environment? The US is a major contributor to global climate change and the US is exceptionally bad compared to other developed nations in GHG contributions arising directly from motor vehicle use. I'm not interested in contrived arguments about slavery but if you want to take a principled stand against a small minority forcing their preferences and the adverse consequences of those preferences on a much larger majority then unfortunately you are on the wrong side of this issue.
But then you have the self-perpetuating problem of stigmatising cycling and promoting car use. Given the numerous advantages of promoting cycling for journeys where it's a reasonable alternative it seems quite understandable that governments wouldn't want to universally ban on-road cycling.
I find this point of view amusing because it is so contradictory to my personal experience. In my case, I started commuting by bike after years of being tired to spend an unpredictable amount of time stuck on traffic, looking through the window at cyclists merrily passing by. Since becoming one of these cyclists, I feel a bit of pity every time that I see people stuck in their useless cars.
I concede that cars can be more useful than bicycles in some circumstances. There are also people like you who legitimately seem to love using cars, and there's nothing wrong with that. But at least in my country:
- there are more bikes than cars
- there are more people who can drive bikes than cars
- every year, more bikes are sold than cars
- most car trips are less than 10km
- most of those cars only carry a single person
- most people would prefer to take the bike than the car if they could
Why do most people still use cars, then? Because there is no safe infrastructure for cycling, and that is the main problem. Improving cycling infrastructure would be a net benefit for everybody, especially for car lovers who would then find their streets liberated of other drivers who just hate being there.
Another problem with cars is that they are ridiculously space-inefficient. Especially when they carry a single person, which is most of the time. A street with 20 people in 20 cars is crowded in dense traffic. The same 20 people cycling or walking are almost invisible, low density occupation of the same space.
It took around fifteen minutes. I'm a pretty quick cyclist and it would have taken over half an hour.
It was also 6 degrees C outside and raining.
I don't consider cycling particularly unsafe even on the road.
But, aside from it being pretty good exercise, it's objectively inferior for me to do it, unless the car infrastructure is unavailable or deliberately crippled.
It is about not promoting car infrastructure to the detriment and ultimately exclusion of alternatives that have the potential to be widely beneficial to society (including, ironically, to those who still drive motor vehicles in our hypothetical alternative reality).
You can provide well for different modes of transportation at the same time. Several European cities have had great success in doing so and they are much nicer places for it.
Which, as I pointed out, could be addressed with more effective barriers between motor vehicle and bicycle lanes. But I think you’re very much overestimating the willingness of Americans to ride bicycles to get around in a Florida or Texas summer, or a Minnesota winter, or up the hills of Seattle or San Francisco, as well as the degree to which Americans are willing to tolerate constantly stinking of sweat.
Unfortunately it isn't as simple as that. Statistically most serious accidents involving cyclists happen at junctions or other localised hazards. For obvious reasons complete physical separation of car and cycle lanes usually isn't possible in those places.
It's because the infrastructure for biking is almost non-existent. Thanks to people who keep saying "just ban bycicles because cars!".
Read and watch this: How the Dutch got their cycling infrastructure https://bicycledutch.wordpress.com/2011/10/20/how-the-dutch-...
The Netherlands is an extremely dense, flat, temperate country, which is ideal for bicycles. The United States is none of those things. Bicycles predate automobiles by decades, but in the US they never even displaced horses or horse-drawn vehicles because even those are more practical than bicycles here.
No. Please read about Netherlands again.
> The Netherlands is an extremely dense, flat, temperate country, which is ideal for bicycles. The United States is none of those things.
Ah yes. All of United States is mountainous land where each person leaves 100 miles from another person.
However, even in places where United States is more like the Netherlands there's almost non-existent bicycle infrastructure (or even pedestrian infrastructure for that matter).
> Bicycles predate automobiles by decades, but in the US
Ah yes. The uniqueness of the United States where bicycles were introduced decades before the car. Unlike any other country where... bicycles were introduced decades before the car.
If you actually made the effort to read the link (and watch the video), you'll see that it's not a unique thing only seen in the US. Let me quote:
"But the way Dutch streets and roads are built today is largely the result of deliberate political decisions in the 1970s to turn away from the car centric policies of the prosperous post war era." The Dutch had the same thing: everything was being converted to roads used exclusievly by motorists, and "the Dutch don't use bicycles for travel". And yet, here we are in 2022.
> Ah yes. The uniqueness of the United States where bicycles were introduced decades before the car. Unlike any other country where... bicycles were introduced decades before the car.
You’re quoting me out of context and mocking me for your own misunderstanding of what I said. What I said was, “Bicycles predate automobiles by decades, but in the US they never even displaced horses or horse-drawn vehicles”.
In the English language, we use words known as “conjunctions” to combine two related thoughts into the same sentence. The first thought was, “bicycles predate automobiles by decades”, which is a general statement that was not specific to the US. The second thought was, “bicycles never even displaced horses in the US”. These two statements are joined by the conjunction “but”. Adding the qualifier phrase “in the US” after the conjunction “but” is done to indicate that the qualifier phrase does not apply to the first thought.
> The Dutch had the same thing: everything was being converted to roads used exclusievly by motorists
They didn’t quite have the same thing, which is the point I made earlier. From Wikipedia:
> Cycling became popular in the Netherlands a little later than it did in the United States and Britain, which experienced their bike booms in the 1880s, but by the 1890s the Dutch were already building dedicated paths for cyclists.[8] By 1911, the Dutch owned more bicycles per capita than any other country in Europe.
> The ownership and use of bicycles continued to increase and in 1940 there were around four million bicycles in a population of eight million. Half of these bicycles disappeared during the German occupation, but after the war the use of bicycles quickly returned to normal and continued at a high level until 1960 (annual distance covered by bicycle for each inhabitant: 1500 km). Then, much like it had in other developed nations, the privately owned motor car became more affordable and therefore more commonly in use and bicycles as a result less popular. That is: ownership still remained high, but use fell to around 800 km annually.[9] Even so, the number of Dutch people cycling was very high compared to other European nations.
This did not happen in the US, where private car ownership caught on much earlier, but also where bicycles were never as popular to begin with as they had been in the Netherlands.
And yet, "US is unique, everything about the US is unique, we are unique, and the wind blows because the trees move".
> Dutch people cycling was very high compared to other European nations.
And yet even other European nations have decent-to-great cycling infrastructure.
One thing the US and Netherlands have in common is that they are both democracies. The Dutch pivoted back to bicycle infrastructure because there was public demand for it. This is not true in the US.
That depends on your criteria. For journeys where they are a viable option bikes are usually much cheaper, healthier, less dangerous, more efficient and cleaner than cars. Of course that doesn't include all journeys that people need to make but it does include many of them.
which is why a very small share of the US population uses them on the roads in the first place.
Somehow I doubt their lack of utility is the reason that almost nobody in the US rides bikes on the road.
They didn’t always. That infrastructure was built and subsidized so they were used.
> Purely from a safety standpoint, outright prohibiting bicycle traffic on motorized roads would be a massive improvement at the expense of inconveniencing a small minority of people
Purely from safety standpoint, making less motorized roads would be a massive improvement and people would conform to new modes of travel just like when cars and interstates were introduced.
Part of the problem is that the US has a lot of roads. So often, the comparison that is made is not “which guardrail is the best”, but, “which places can we budget to install a guardrail?”
This is why even though the safety of cable barriers is disputed, the overall number of lives saved by them is usually said to be quite positive, because we can afford to install more of them. Hitting a shitty cheap guardrail (or cable) is usually better than hitting a vehicle head-on or hitting a bridge support.
Also, those end caps on that guardrail are not considered a safe design and aren’t really used in the US anymore because they spear vehicles when hit directly on the end.
Jersey kerb has become ubiquitous worldwide.
Interestingly, the alternate designs often used (guyed wires, steel barrier) have good and bad points, for survivability if an impact is unavoidable. They "give" -and in some circumstances, thats exactly what you want. Jersey Kerb is for the "nope: no giving here: wear the decelleration, hard" situations where giving (eg. into the oncoming traffic flow) would be worse overall.
I thought that is what the plastic filters at the bottom assisted with
[1] https://arco.co.nz/wp-content/uploads/2017/12/m23-road-safet...
Of course they're cheap and easy to install, but their main downsides are, having a higher rate of killing those who get caught up in them and are only really good for one use.
[0] https://www.google.com/maps/@48.2347588,-122.237414,3a,75y,3...
They had installed miles of these wire rope barriers in the last 10 years and I have seen them being installed up in Oklahoma too.
Of course, once there is an accident the wire rope may have been strained past its rated capacity so it needs to be replaced. You can buy spools of the wire rope [0] from recycled materials handlers. Along the interstates near my place you will see skid marks into the cable barriers every time the highways get wet. If the weather was really bad you could find a dozen new collision spots in a 20 mile stretch. It keeps the repair crews busy. People drive too fast out here nowadays.
The pdf document posted is a great read. I see several barrier designs there that I have never seen in use anywhere and all the familiar ones too.
The most common barrier for many years in Texas has been the W-beam SGR04B type or similarly, the thrie-beam rail SGR09B but they tend to use treated timber posts for mounts. The newer installations have impact-absorbing lead-ins to help prevent fatalities.
A couple years ago I was driving home along a two-lane US highway (not an interstate) where the W-beams were used at every creek or river crossing. As I rounded a long curve in the highway headed downhill towards a creek crossing about 1000' away (305 m) I saw skid marks leading to the edge of the highway where the guard rails should've been. The skid marks were obviously made by an 18-wheeler (semi) truck-trailer. The guard rail was completely wiped out and as I passed the creek I saw where it came to rest. The entire length of rail was curled and twisted with one end up more than 30' (9.1 m) in a tree beside the creek more than 30' (9.1 m) off of the highway and the other end curled down near to the ground. It had been launched up into the tree by the force of the collision.
[0] https://www.repurposedmaterialsinc.com/median-galvanized-cab...
> To contain and redirect a 36,000-kg gasoline tanker after impacts at high angles and speeds, a 2290-mm (90-in) concrete barrier is required.
[ picture of hard impact big truck side humping and sliding into said barrier ]
However the US improvement is 3-5X less than other similar countries. For details on that and links to some data sources, see https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4103211/
Lets not forget that is only necessary because the automotive industry is barbaric to begin with. Let's recall why trains dont require advanced crash barrier design like this.
The basic principles of concrete barriers are not generally known or understood. Concrete barriers appear to be simple and uncomplicated, but in reality, they are sophisticated safety devices.
I wonder how much of this stuff from 2000 is still relevant?
Back then moor anchor law was still in full swing, for one thing.
In 1999 I was driving a '68 Plymouth Barracuda southbound on US395 in Reno, NV USA, doing 65-70mph in the fast lane (the lane closest to the middle barriers).
Being an older car, the 'Cuda had a tendency to drift to the left, toward the barriers. I corrected to the right, as I always did. Nothing happened. The joint connecting the steering column to the steering box, held together by a flimsy piece of sheet metal, had come apart.
I was now a passenger, and didn't dare not slam on the brakes, lest the all drum brakes send me in some unknown direction as they often did. If you're getting the idea this car needed some TLC, you'd be right.
With only a second or two to think about what to do, I simply let off the accelerator. The car started slowing slightly, but by the time the car drifted gently into the barrier, I was still travelling at at least 60mph.
My imagination saw me bouncing off the barrier, back into the fairly steady Reno afternoon traffic, where I'd be bounce like a pinball between other cars, eventually going sideways, flipping, and probably not surviving. I hoped nobody else got seriously hurt.
But that wasn't what happened.
The Cuda's front left tire caught the bottom of the barrier- the steepest angle the barrier has- and the front tires immediately slammed hard to the left. Now, both my front tires were at full lock left at 60mph. I expected to flip over.
Once again, that wasn't what happened.
Instead of flipping, the front left corner of the car became airborne for only a moment. Without traction, the front end just came back down, unable to continue its journey past about 40 degrees to the right. I'm guesstimating here, since at this point I was simply enduring the ride and out of my mind with fear. I didn't scream.
The cycle repeated itself, and each time the car lurched into the air, it lost speed. After several cycles, I realized that the car had stopped climbing the barrier and was the front tires were just skidding forward against the barrier and the pavement. It was only then that I thought it safe to press the brakes.
Finally, the car came to rest. After I stopped shaking internally, I realized the car's engine was still running. I turned it off. I was alive, and I realized in a very short time that I owed my life to the engineers who designed the Jersey barrier.
After reading this article, my appreciation soars even higher. All of the things that happened to me in my car weren't accidental: They were designed.
Thanks, Jersey barriers. I owe you one.
----
As an aside to that story, I was about to horse-trade that car (straight across, no money changing hands) for a 1969 Land Cruiser FJ55 wagon just that week. I was sure that the trade would be a bust, but when I looked out the window, I saw that the only body damage was a bent fender lip! The barrier's design really shined even greater in that moment.
$100 to a not very friendly tow truck driver got me and the car home, and the very next week I was driving a 1969 FJ55 wagon. That vehicle was actually less safe, but way, way, more fun. And the new owner? He was doing a ground up resto anyway, and didn't care about the bent wheel, ruined tire, and broken ball joint. It was all being replaced anyway.