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Comment by zo1 | Hacker News Reader

Wow. The start of that concrete lane-divider looks incredibly dangerous for a highway. It pretty-much just "starts", with only some sort of object that they call a "crash attenuator" in front of it. I would imagine its purpose is to dampen/dissipate kinetic energy and maybe deflect oncoming objects from hitting the concrete slab directly.

I don't even see any sort of road-bumps to warn drivers of this dangerous obstacle approaching.

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Out of curiosity, are you not in the U.S.? These types of lane dividers are incredibly common throughout the country.

Note that I'm not defending the safety of them; I'm just surprised to see someone call them out as a hazard as they're such a common sight.

Dutch citizen here, I have never seen something like this.

To compare, here's a similar situation in The Netherlands:

https://www.google.nl/maps/@52.0928662,5.1734685,3a,75y,281....

Points of interest:

- big solid white arrow, line-fade is nearly impossible

- white-green sign indicating that the road is splitting

- big shoulder in the continuation of the division

- loads of grass instead of immediately using a metal barrier

- gently rising metal barrier, so driving straight into it will result in something like this: http://cdn.brandweersassenheim.nl/large/269dezilkvangrail104...

Same goal, but a completely different approach.

This is pretty apples-to-oranges. You see things like this in a lot of less dense U.S. areas as well. But in the crash example, it's right in the middle of an interchange, with the lane needing to form and rise quickly. Additionally, the gently rising metal barriers aren't safe in many situations because of their ability to launch cars. That's why they've been replaced by crash attenuators and sand/water barrels. Unfortunately the crash attenuator wasn't replaced after a recent (<1 week ago) accident, ensuring the next accident was fatal.

Here's an accurate U.S. analogue to your example: https://www.google.com/maps/@41.0286482,-102.1517159,3a,75y,...

Meanwhile, here's a Dutch example: https://www.google.com/maps/@51.9305956,4.4371182,3a,75y,66....

Turns out sometimes you need crash attenuators because space isn't infinite. Also, there's no grass in sight here.

Here's another example: https://www.google.com/maps/@51.9239112,4.4203482,3a,67.8y,2...

No sloping barriers, because they're not always safer.

Well, yes and no.

First, your counter-example is, ironically, pretty apples-to-oranges, as it is literally in the middle of nowhere. Meanwhile, the municipality where my interchange is located has a population density 1.5x that of Mountain View.

About the A20: it was built around 1970, inspired by American designs. Something like this would probably not be built today. Meanwhile, the specific ramp where the accident occurred, was constructed around 2006.

I do agree that safety measures should be adjusted according to their location, there is indeed no one-size-fits-all solution here.

You're right that my first example is in the middle of nowhere, but there's a good reason for that. American and Dutch city designs differ so much to make them incomparable. Even NYC has 0.63 vehicles per household (http://www.governing.com/gov-data/car-ownership-numbers-of-v...), and San Jose (the closest to Mountain View I could find) has 2.12. There's a lot more traffic to deal with, and a lot more sprawl, meaning less space for interchanges and long ramps.

Why are roads in the US so post-apocalyptic? Even your good example here looks horrible.

Hmm, perhaps something to do with there being more road miles in the US than in all of Europe combined?

The European road network is actually slightly larger than the US one (~6.5 million km vs ~7 million km).

Which makes the point just fine, when you compare the U.S's 326 million to the EU's 508 million.

Well, 741 million, I don't believe the road network figures were restricted to EU members only.

Here's an example of a crash attenuator right near your example: https://www.google.nl/maps/@52.0928978,5.1609792,3a,60y,305....

Edit: Also, that gore is freshly painted. Here's the same gore with faded paint. Mind you, it wasn't as bad, but even there you get faded painting: https://www.google.nl/maps/@52.0928706,5.1608083,3a,75y,109....

I've tried to find something similar in an urban area in Britain, here's one in Birmingham: https://www.google.nl/maps/@52.4901761,-1.889549,3a,69.6y,5....

That fence wouldn't be fun to drive into at full speed, and the lane markings are worn, but it's still far less awful than a concrete wall.

At highway speeds, if that "fence" is strong enough to prevent vehicles from falling from the raised left lane into the lower right lanes, then it would seem likely to cut a car in two. I think I'd prefer the crash attenuator.

That segment of the A38 has a 30MPH limit, with the right fork increasing to 50MPH. The dynamics of any crash would be very difficult.

The intersection in the Tesla crash is pretty sub par by US standards. Most highway off ramps are as you described. In space restricted areas we tend to use tons of reflectors then water/sand barrels or metal crumple barriers instead of gently rising barriers and a grass infield.

In basically all cases where there's a lot of pavement that isn't a lane there's diagonal lines of some sort that make it very clear that there isn't a lane there. A good chunk of the time there's a rumble strip of some sort.

In rural areas there's less signage, reflectors and barriers but the infield is usually grass, dirt or swampy depending on local climate.

Edit: and I'm wrong because why?

I wouldn't think wrong, but it seems to imply "AVs need great roads or bad roads, on mediocre roads they might kill you for no obvious reason, gee, too bad."

Such "pretends to work but actually doesn't", IMNSHO, would be far worse than "doesn't work there at all"

Granted my experience is my own and shaped by the areas I've lived in, but I'd say the crash barrier is pretty standard by US standards.

A few reflectors, a crumple barrier or some barrels and you've got a highway divider start! Certainly not as lengthy or as well marked as the Dutch example. This one I used to drive by in KC almost daily looks similar to the Tesla accident one (granted, this example does have some friendly arrows in the gore): https://www.google.com/maps/@39.0387093,-94.6774548,3a,75y,1...

I have also seen so many people crash into this one that they put up yellow hazard lights: https://www.google.com/maps/@39.0790636,-94.594365,3a,75y,17...

That's an interesting (and amusing) picture, but I'd expect many more incidents of a "gently rising metal barrier" causing a vehicle to roll over.

The metal barriers are usually quite safe and designed to absorb a lot of energy. (Plus rolling over is safer than crashing into concrete)

I'm in the EU. This road does look a little bit hazardous to me; like it was designed 60 years ago and never updated.

- The area one is not supposed to drive in doesn't appear to be marked. Where I live, it would be painted with yellow diagonal stripes.

- On a high-speed road, there would be grooves on the road to generate noise if you are driving too close to the edge of the lane.

- Paint on the road is rarely the only signal to the driver (because of snow or other conditions that may obscure road markings). There would be ample overhead signs.

- Unusual obstacles would always be clearly visible: painted with reflective paint or using actual warning lights.

- We rarely use concrete lane dividers here. Usually these areas consist of open space and a shallow ditch, so you don't necessarily crash hard if you end up driving in there. There's usually grass, bushes, etc. There are occasional lane dividers, of course, when there's no space to put in an open area. However, the dividers are made of metal and they are not hard obstacles and fold or turn your vehicle away if you hit them (and people rarely do because of the above).

I'm sure there are some dangerous roads here, too, but a fatal concrete obstacle like this, with highway speeds, with almost no warning signs whatsoever, is almost unheard of.

Excessively long, unstriped gores are not at all common in the Eastern US. This is bad engineering and poor maintenance.

If anything the US tends towards far too little merge space than excessive. Almost every city has a blind yield entering the freeway somewhere.

This is a problem with old highways that were upgraded to substandard interstates. That isn't the case here with plenty of room to build a safer design.

I live in South Africa. We see items such as this more commonly:

https://www.google.com/maps/@-25.833477,28.2391574,3a,75y,75...

https://www.google.com/maps/@-25.8317095,28.2407035,3a,75y,7...

However, it's not consistent. Some end quite abruptly as well, and have a plain sign in the middle without any slowly-rising divider.

I had never heard of crash attenuators before, but they seem really impressive! This one was the "SCI smart cushion" model. According to the manual[1] it can reduce the acceleration from a collision at 100 km/h (63 mph) to less than 10G, so even a direct frontal collision at highway speed would be survivable[1]. That's pretty amazing.

[0] http://4fhmzg4ct6wezwll3wmp9kl9.wpengine.netdna-cdn.com/wp-c... [1] http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.212...

The crash attenuators are usually good enough to save people's lives. There are small grooves in the sides on some of the freeways in CA but they aren’t everywhere.

The problem with the attenuators are that they don’t get replaced fast enough which makes these accidents a lot deadlier.

You can see the difference between a used and unised attenuator in this article. http://abc7news.com/automotive/tesla-claims-missing-safety-b...

Agree. The area leading up to the barrier could at least be striped off.

Yes, I'd expect to see something like https://goo.gl/maps/dbp2fx79ihz

I could easily imagine a stressed human driver unfamiliar with the area following that unstriped gore area as a 'lane', too.

And you'd think that basic paint striping would be comparably cheap. It's incredible that such a deadly point wouldn't have it.

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