Median Cable Guardrails-good or bad?

[Duke87]

From MDOT's Brochure:

Cable guardrail reduces the severity of crashes, and is a very cost-effective safety measure when compared to other barriers. Cable barrier is designed to prevent a vehicle from crossing into lanes of oncoming traffic. The cable also absorbs most of the impact, preventing the vehicle from bouncing back into traffic.

Looks like bounce-back isn't a problem.

[Terry Shea]

From MDOT's Brochure:

Cable guardrail reduces the severity of crashes, and is a very cost-effective safety measure when compared to other barriers. Cable barrier is designed to prevent a vehicle from crossing into lanes of oncoming traffic. The cable also absorbs most of the impact, preventing the vehicle from bouncing back into traffic.

Looks like bounce-back isn't a problem.

Look where the van ends up in the video.

[froggie]

There's exceptions to ANY situation.  Surely you don't believe that concrete or standard metal guardrail barriers are infallable...

[Duke87]

Look where the van ends up in the video.

It flipped over somehow. It's hard to draw any conclusions from just that picture. With no footage of the incident happening, we don't know exactly what happened and can't judge how the guardrail functioned.

Though, judging by the fact that the people inside survived, it would seem the guardrail did its job. We can't absolutely say that without the guardrail the van would have veered all the way into oncoming traffic, but there's certainly a chance it would have, and if it did the result would no doubt have been fatal.

Now, for some previous issues...

What happens when the cable snaps and goes through a vehicle and/or a body in the vehicle?

If designed and installed properly, the cables won't snap.

Most vehicles that go into the median aren't going to cross all the way over into oncoming traffic.  Now this same scenario creates the increased risk of bouncing off the barrier and back into traffic every single time a car leaves the inside lane, not crossing all the way over the median into oncoming traffic once in a blue moon.

Just to point something out here, the guardrail isn't right up against the shoulder. Entering the median and not hitting it is still very possible, and likely probable for a minor temporary loss of control that only results in a little bit of veering before the motorist recovers and keeps driving.

Now each instance is going to cause severe damage to their vehicles along with the risk of being thrown back into traffic

Only if you're really veering off the road and hitting the barrier at a significant angle. A glancing blow will scrape and dent the side of your car real nicely, but not result in "severe damage". The people getting "severe damage" will be the people who have a significant risk of crossing into oncoming traffic if nothing stops them first.

I think insurance rates are going to skyrocket

Well, we'll see, won't we? Though somehow I don't think so. Consider that statistically, most accidents happen relatively close to home (i.e., on local streets, not the freeway), anyway - so any potential increase the median guardrails may cause is an increase in the minority of situations.

[andytom]

From MDOT's Brochure:

Cable guardrail reduces the severity of crashes, and is a very cost-effective safety measure when compared to other barriers. Cable barrier is designed to prevent a vehicle from crossing into lanes of oncoming traffic. The cable also absorbs most of the impact, preventing the vehicle from bouncing back into traffic.

Looks like bounce-back isn't a problem.

Look where the van ends up in the video.

If the forces were high enough to put the van across its own roadway and on its top with the cable barrier, the forces would certainly be high enough to get the van into oncoming traffic without a barrier at all.  Most people would much prefer 20-30 MPH collision speed differentials to those of 100-120 MPH.

--Andy

[joseph1723]

Ontario used to install these but most have been replaced with a Ontario Tall Wall barrier or jersey barriers. I personally think they are dangerous compared to concrete or steel guiderail especially when placed in a narrow median which was the typical installation in Ontario.

[Terry Shea]

From MDOT's Brochure:

Cable guardrail reduces the severity of crashes, and is a very cost-effective safety measure when compared to other barriers. Cable barrier is designed to prevent a vehicle from crossing into lanes of oncoming traffic. The cable also absorbs most of the impact, preventing the vehicle from bouncing back into traffic.

Looks like bounce-back isn't a problem.

Look where the van ends up in the video.

If the forces were high enough to put the van across its own roadway and on its top with the cable barrier, the forces would certainly be high enough to get the van into oncoming traffic without a barrier at all.  Most people would much prefer 20-30 MPH collision speed differentials to those of 100-120 MPH.

--Andy

Now how can you make such a statement?  There is absolutely no way we can tell if the van would have completely crossed the median or not.  We don't know how wide the median is, how deep the median is, what angle the van hit the cables at/would have entered the median at, what speed the van was traveling at, etc.  All we can tell is that the van crossed two lanes of traffic after bouncing off the cables and landed on it's roof, facing in the wrong direction, creating a very unsafe scenario.  It may or may not have crossed over w/o the cable barrier and that's all we can say with any degree of certainty because we simply do not have enough information to draw any valid conclusions.

And that's exactly my point regarding this entire matter.  We have not been given enough information by MDOT to determine if these devices are truly safe or not and whether or not they are worth the cost or not.  I still believe that 40 million dollars could be put to much better use to save lives.

[agentsteel53]

no more bickering about the van.  any other discussion on the topic is greatly welcome (for example Joseph's post) but any further back-and-forth about this one example will be deleted.

congrats, Terry, you got the last word.  your prize will be put in the mail within 4 to 6 business days.

[US71]

In a FWIW, Missouri uses cable barriers along I-44. They are 3 strands and sit in the middle of the median. They also appear to not be as tall as Oklahoma's barriers which, BTW, are sometimes on one side of the median or the other , or sometimes down the center of the median.

Perhaps someone can explain if cable barriers down the center of the median are any more or less safe than cable barriers that are NOT centered? Is there any evidence that one is superior to another?

[hbelkins]

In a FWIW, Missouri uses cable barriers along I-44. They are 3 strands and sit in the middle of the median. They also appear to not be as tall as Oklahoma's barriers which, BTW, are sometimes on one side of the median or the other , or sometimes down the center of the median.

Perhaps someone can explain if cable barriers down the center of the median are any more or less safe than cable barriers that are NOT centered? Is there any evidence that one is superior to another?

Kentucky has installed these in a number of places with a high rate of crossover accidents. They may be closer to one carriageway or the other, or right in the middle. I've been told that the characteristics of the median, the curvature of the highway, etc., play a part in how the cable barriers are placed. If you drive along the stretches of I-64 near Huntington, WV and between Huntington and Charleston where they have been installed, you'll find in some places they will be adjacent to one carriageway for awhile and then will cross over the center of the median to be closer to the other carriageway. OTOH, where they have been installed along KY 4 (New Circle Road) in Lexington, they are adjacent to the inner loop where all the traffic flows clockwise.

[Scott5114]

I wish that NCDOT guy who posted to MTR a lot (John Lansford?) were here now. He did a lot of work involving cable barriers, if I remember correctly, and would be interesting to hear from in this discussion.

[hbelkins]

Speaking of cable barriers, Tennessee has installed them sporadically along I-40 between Nashville and Memphis. I could not see any compelling reason why they were installed at these locations and not in others, unless there have been crossover accidents at these specific places.

Texas has a few cables on I-20 and I-30 east of Dallas, but in a lot of places they have concrete jersey barriers placed right next to the passing lane of the route, not in the median but at the edge of the paved surface.

[mightyace]

On my recent trip, I saw them on I-76/US 224 west of Akron toward I-71 and many of them were on both directions!

[rawmustard]

Looks like MDOT will consider changes after all.

[jdb1234]

I do not mean to bump a old thread.  I had an up close and personal view of a concrete jersey barrier on I-65 here in Birmingham and am sure glad it was there. 

[golden eagle]

Cable railguards were just installed on I-220 in the Jackson a couple years or so ago after a series of crossover accidents took place. One accident killed a 17-year old high school student when a driver going at a high rate of speed cross the median and hit his vehicle. I can't recall any crossover accidents since the rails were put in place.

[national highway 1]

Cable railguards are extensively used in Australia, esp in NSW.
They are sometimes used to guard deep ravines and are an alternative to steel guardrails.
Eg , Hume Hwy, Federal Hwy, Kosciuszko Rd, Pacific Hwy

[golden eagle]

I-20 has cable rails near the left lanes on both sides of the high in Vicksburg. However, there are gaps in between (though not continuously). I'm guessing the gaps are for emergency vehicles.

[Scott5114]

"The ground in the median can be too soft to hold up the rails, said Nick Schirripa, spokesman for MDOT's southwest region. And putting barriers in the median can let a car fly over the rails, he said."

So you do like ODOT (and probably every other DOT) does and mount the pylons on a narrow slab of concrete.
[/quote]

Well if the median is too soft there's no chance of a car crossing over, period.

Bullshit. If a car is going at a sufficiently high rate of speed it will not have the chance to stop sink in the mud. 

Where the hell is all this perpetual moisture making the medians the consistency of a bag of Stay-Puft marshmallows coming from, anyway? Did they intentionally build all the highways through a bog or something? Do special MDOT Molasses Division trucks go through every Thursday to top off the medians?

[bulldog1979]

"The ground in the median can be too soft to hold up the rails, said Nick Schirripa, spokesman for MDOT's southwest region. And putting barriers in the median can let a car fly over the rails, he said."

So you do like ODOT (and probably every other DOT) does and mount the pylons on a narrow slab of concrete.

The cable barriers along I-75 north of St. Ignace were all set in small concrete footings, much like you would do with a fence along your property.

I know that there are some spots on I-96 between Grand Rapids and Lansing where the median is essentially a marsh, but the median is also wider there so that the barriers aren't needed.

[jdb1234]

In my opinion, cable-stay median guardrails are good.  My reasoning is that at worst they prevent people from trying to make illegal U-Turn in the median.  My sister totaled her first car back in 2006 and my dad was involved in an accident earlier this year on I-10 near Tallahassee due to vehicles attempting to make a U-Turn in the median.

ALDOT has used cable-stay in a few spots on I-65 most notably in Butler and Cullman Counties.

[Scott5114]

Ever been to Michigan?  We get a lot of rain.  We get a lot of snow in the winter.  There's basically 2 seasons (not counting construction season); rainy season and snowy season.  During snowy season the ground is hard but it's covered by inches if not feet of snow.  In the spring it melts and rains like hell making the ground soft and muddy. 

Average Monthly Precipitation (Source: National Weather Service)

City	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Marquette, MI	2.04	1.35	2.24	2.35	2.66	2.74	2.64	3.01	3.42	3.03	2.60	1.95
Grand Rapids, MI	2.03	1.54	2.59	3.48	3.35	3.67	3.56	3.78	4.28	2.80	3.35	2.70
Detroit, MI	1.91	1.88	2.52	3.05	3.05	3.55	3.16	3.10	3.27	2.23	2.66	2.51
Oklahoma City, OK	1.28	1.56	2.90	4.28	5.44	4.63	2.94	2.48	3.98	3.64	2.11	1.89
Tampa, FL	2.27	2.67	2.84	1.80	2.85	5.50	6.49	7.60	6.54	2.29	1.62	2.30
Hilo, HI	9.74	8.86	14.35	12.54	8.07	7.36	10.71	9.78	9.14	9.64	15.58	10.05

Remember, this is precipitation totals in inches. That means snow is included in the total as its melted-down volume (which is what you're wanting, anyway, since this would be the amount of moisture that would be available to soften the median.

And what we see from this is...you're full of it. Michigan gets roughly the same amount of rainfall as Oklahoma does, but more evenly distributed (much of Oklahoma's rainfall comes in April through June). Detroit, the largest city in the state, gets even less precipitation than Grand Rapids and Marquette do. Meanwhile, if you compare Michigan to Tampa and Hilo, you see that really, it's not that much.

Also, your position requires (1) the car to be going slow enough when entering the median for the consistency of the soil to be a factor in significantly stopping it and (2) atmospheric conditions to cooperate. If for whatever reason Michigan receives less rainfall than normal, the safety record is going to deteriorate because you pinned all your safety hopes on something that is essentially twice as random as any slot machine.

A cable barrier is obviously going to be much more effective than an earthen median on its own, since it doesn't depend on the weather for it to work.

[Scott5114]

You may well have a similar amount of rainfall in Oklahoma, which certainly does surprise me, but you certainly don't have as humid an environment

Statistics for May:

Grand Rapids, MI
Average Morning Relative Humidity = 79%
Average Afternoon Relative Humidity = 50%

Oklahoma City, OK
Average Morning Relative Humidity = 84%
Average Afternoon Relative Humidity = 52%

with an area full of lakes, rivers, marshes, swamps and wetlands like we do here.

https://secure.wikimedia.org/wikipedia/en/wiki/List_of_lakes_in_Oklahoma

As I stated before, this presented little to no problem in the past.  It's not uncommon to see dozens of cars in the median on snowy, stormy days.

That's because on your average snowy day people are not traveling at 70 miles per hour. When people slide into the median on an icy day they're normally doing, what, 40 mph tops?

Now vehicles which would have harmlessly stayed in the median with little to no damage are being ripped to shreds because the idiots who decided to install these decided to place them literally a couple of feet from the roadway instead of in the middle of the median.

They're "idiots", huh? Would you care to give us all your Michigan P.E. certification number? I've been critical of ODOT in the past, but only about things that I feel qualified to criticize, like layout of road signage. I know fuck all about bridge design so I'm not going to complain about their bridge designs since I really don't know what I'm talking about. I certainly don't call them idiots because I'm sure it's more of a case of poor quality control or ineffective management than flat-out idiocy.

Did you read the comments at the bottom of the WOOD-TV article? It's not just me, people here are overwhelmingly against these barriers being installed. [...] and it should be quite clear that the people here in this state don't want them here.

No. Comments on road-related news articles are generally made by people who are uninformed. Also, judging that an entire state holds some opinion from the comments on one article on a news site is a rather hasty generalization, since it has a self-selecting bias (only people who feel strongly one way or another against the cables are going to post there).

That's why when I started this thread I specifically placed it in the Midwest/Great Lakes region and put Michigan in the Title of the thread.  I guess it was moved and the title changed for "political" reasons.

The moderation totally moved your thread because it's all part of the grand plan we have posted in the staff lounge to shame all of the Republicans into submission. Man, you should read it some time. We're just waiting for someone to make a Reagan reference so that we can all go through our elaborate 13-page script bashing him. I tell ya, we're gonna be in stitches when David Backlin reads that "tear down this wall" pun on Page 11.

In fact I personally don't know even 1 person who is in favor of these barriers.

And how many of the people that you personally know are as involved with transportation as the people here? How many of them are P.E.'s? I don't know one person who is in favor of these barriers either, because none of them have ever thought about them before and can't be arsed to.

[bulldog1979]

Terry: I live in the Greater Grand Rapids area, and I support their installation. Period. Now, you'll have to claim that all of Michigan except me doesn't want them, but I doubt I'm the only one in the state that wanted them. After all, no one forced MDOT to install them, so some people in Lansing wanted them.

The fact remains, it's cheaper to replace a bumper that's damaged from the cable barrier than to attempt to replace a life lost from a head-on collision. I say that with confidence because you can't bring back the dead, unless you're holding out on new medical technology on us.

[jjakucyk]

I'm not sure I should jump in on this thread or not, but what the hey.  Here's my observations on what I've seen here and in person. 

First of all, I would agree that any cable barrier, standard metal guardrail, or concrete jersey barrier should not be installed immediately adjacent to a narrow left shoulder.  This makes any crash into that barrier block the left travel lane, and if installed on both sides of the median it's double the infrastructure and cost with virtually no added benefit. 

That said, a cable barrier should be in the center of the median.  If it's a narrow median, it's all that much more important to have it since the chance of crossover accidents is higher.  Whether a wide or a narrow median, the cable barrier will stop most if not all crossover accidents, the deadliest and most damaging.  Yes, there is a higher likelihood that vehicles entering the median will be damaged, but with the barrier in the center, only half of all such vehicles would hit it, the rest would stop short.  Soggy turf or snow can't be counted on to stop wayward vehicles since those conditions are not constant.  Even in wet and snowy areas, there's still a long time of the year where the ground is bare and either frozen or dry.

So again, a cable barrier (or any barrier) on both sides of the median instead of in the center is a bad idea for a number of reasons.  That doesn't mean cable barriers are universally a bad thing.  Also, anyone who can't keep their vehicle on the road in snowy weather really doesn't deserve much sympathy.  Hitting a nearside barrier, even at the types of speeds you should be driving in snowy weather, is going to be damaging, but going off the road isn't necessarily harmless either.  Sinking into soft dirt or running through a snowbank with who-knows-what hiding in the ground can lead to a busted radiator, torn fuel or exhaust lines, damage to the suspension, or even a broken axle.  Those things could be just as bad as busted fenders and bumpers, and that's only after you get un-stuck.  The stuck cars are abandoned until they can be pulled out, but the ones that crash at those speeds are usually able to keep going. 

The whole point though is that preventing fatal accidents, especially ones that can involve many innocent people, is justifiable even if it causes some more superficial damage to the vehicles of people who can't keep their own car on the road.