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Computer Failure Causes Gridlock In MD County
Uncle Rummy writes "A central traffic control computer in Montgomery County, Maryland failed early Wednesday morning, leading to widespread gridlock across the entire county. The computer, which dates to the 1970s, is the single point of unified control for all traffic signals in the county, which comprises a number of major Washington DC-area suburban communities. When the system failed, it caused all signals to default to stand-alone operation, rather than the highly-tuned synchronization that usually serves to facilitate traffic flow during rush hours. The resulting chaos is a yet another stark reminder of how much modern civilization relies on behind-the-scenes automation to deliver and control basic services and infrastructure. The system remains down Thursday, with no ETA in sight."
I smell foul play...
Quick, someone get Bruce Willis!
Most of those boxes have a "conflicting green" detector circuit that automatically puts the signal in "safe mode" when it detects two conflicting green lights.
On simpler systems, "safe mode" is all-way flashing red lights.
I guess if you knew what wires to mess with you could disable this safety feature.
Physical access is root access.
Knowledge is how to play a game, intelligence is how to win, wisdom is knowing what game to play.
That wouldn't make it any better.
I haven't read the article, but if the summary correctly reflects the situation, the traffic lights are all working - they're just working independently, so rather than being in sync so the main flow of traffic never has to stop (or stops less) they're all just doing their own thing.
The preferred solution is to not have a problem.
So the default behavior is basically traffic lights in Los Angeles on a normal day? I feel soooo sorry for them. ;)
According to this it was a Data General main frame from the 1980s and not from the 1970s. Anyone know what model?
For those who aren't familiar with Montgomery County, MD. It is one of, if not the richest counties in the nation. I find it amazing that even in a county like this, the public infrastructure is crumbling.
They had a massive water main break earlier this year that made the national news.
I live here too and it was mayhem last night. It took me 2.5 hours to get home from work which usually takes 25 minutes. (6 miles) Many of my coworkers and friends have also reported major headaches... We were sitting at traffic lights with nowhere to go for sometimes up to 5 cycles of the lights. What I heard is that there is a different timing for rush hours that lets more traffic flow south in the morning and north in the evenings. The worst areas according to news reports are Rockville Pike, which I experienced last night, Connecticut Ave, Georgia Ave and Rt 29. The official word is that some board blew in the main computer and they are unable to find "parts" to replace it. I am not certain about the details. The county website is reporting that all traffic lights are going to have to be manually updated one-by-one. There are 800 intersections.
Wouldn't matter. The traffic lights were working fine, the problem was there was no central system that could take a larger view of traffic and sense that turning a light green a block away could prevent a gridlock issue at a specific intersection. Intelligent traffic control takes traffic that is approaching a heavily congested area and intentionally slows it down, while freeing up cars to LEAVE congested areas more quickly. They help prevent gridlock by making sure that once a specific light turns green you can actually drive through the intersection, and turns the light red BEFORE cars get caught in the middle of an intersection.
You see this kind of design a lot in well-designed roads in smaller towns. Busy towns will tend to have lots of stop signs coming in to town, but try to reduce stop signs when leaving town. The idea is to keep inbound traffic from filling the town faster than departing cars can leave by making sure cars that are leaving can do so as quickly as possible, while cars wanting to come in will be intentionally slowed down.
A meter maid has no more information about traffic flow at adjacent intersections than an autonomous single light would.
"This post contains words, known to the State of California to cause thought. Wash brain thoroughly after reading."
Damn! 70s? Talk about Return on Investment.
The WashPost, in another article touts Fragile Technology.
I reach for my 70's era calculator and estimate the operational life of 34 years for this system. Some Fragility. Who or what at the Post has been there that long.
Wonder if its some ancient PDP version or an small IBM mainframe. The article is scarce on details. Parts for either are getting hard to find except in the scrap market.
Still you have to wonder why it wasn't ported to some other platform if nothing else as an exercise in disaster preparedness. Any commodity computer could do the job.
There is a lot of stuff like this still in service. I saw a PDP 8 monitoring turbines in a hydro Power station, and asked about where they get that fixed. The reply was it never broke down, but they had stockpiled 6 replacements, tested each yearly, just because they realized how old it was. Nobody knows exactly what it does anymore.
Sig Battery depleted. Reverting to safe mode.
IANATE (I Am Not A Traffic Engineer), but I've had the opportunity to talk to some over the years. From what I recall of those conversations, most, if not all, traffic signals are failsafe. They cannot have colliding greens, and they won't generally just turn off. Even in the event of a power failure, they're suppose to stay up on batteries for a while.
I have seen their failsafe behavior fail though. I was once driving on a dark foggy night. Visibility was very very poor. I was staying in my lane, but I couldn't see much else. I had a long drive in a rural area, and I was coming into an urban area. I expected to see street lights and traffic lights, but there were none. As I was driving, another car shot across the road just ahead of me, missing me by just a few feet. He didn't see the traffic light that wasn't working either. I called the police, so they could station an officer there. Their response was "Are you crazy? No one can see at that intersection. He'll get hit." Hmmm, good logic. At least no one got killed there that night.
Serious? Seriousness is well above my pay grade.
The blue is from appraching the light too fast. You're aproximately going 20% the speed of light. SLOW DOWN.
Slashdot's rate-of-post filter: Preventing you from posting too many great ideas at once.
if the summary correctly reflects the situation
Please mod parent funny.
... to mediate traffic instead of traffic signals, they wouldn't have needed the aging old single-point-of-failure computer in the first place, because roundabouts (a) require no computers, (b) require no electronics at all, (c) require no electricity, and (d) don't require maintenance. What's more, since they allow motorists to preserve some momentum in all but the most congested traffic, gas consumption from forced arbitrary deceleration and acceleration is reduced. The only intelligence they require isn't of the artificial sort at all, only a smidgen of it from the motorists using them. They are un-powered and self-adjusting to traffic flow.
Would anyone like to take a stab at how much energy and man-hours is expended on the traffic signal network in the United States every year?
That's why in my town we have Braille traffic lights.
Silly billy! The system is now protected by a new set of rules. You have to have upper and lowercase, a special character, and a number.
The password is now: P@ssw0rd
See? The system is now completely secure!
"This post contains words, known to the State of California to cause thought. Wash brain thoroughly after reading."
Except for one light in Buffalo, NY.
The folklore is that the Irish workmen thought that green should always be on the top.
The light has been reaplced, IIRC, several times, but remains the only inverted traffic light in the US.
"Trolls they were, but filled with the evil will of their master: a fell race..." -- J.R.R. Tolkien on Olog-hai
A meter maid has no more information about traffic flow at adjacent intersections than an autonomous single light would.
Then how about a Beowulf cluster of meter maids? (with walkie talkies of course)
call me FOSS im the boss with the sauce and the source
When I lived in Kentucky, we had an ice storm that knocked out power in Lexington for the better part of a week. The loss of traffic lights meant every intersection was supposed to turn into a 4-way stop. Which meant that every car came to a halt (in theory) at every intersection for a second or two. My 8-mile 15-minute drive to work turned into 3 hours one morning. I finally found a parking lot, parked my car there, and walked the remaining 3 miles. It was faster. Seriously - I recognized a guy 2 cars ahead of me and he arrived at work 1/2 hour after I did.
The reality was that people were assuming that dark lights meant that either (a) it was a 4-way stop, (b) people on the "larger/main" road had right-of-way, (c) I have no idea so I'm going to creep through, or (d) screw it, y'all, I've got the big fukkin truck - get outta my way.
On the third day, they deployed every police officer, meter reader, and anyone else with a pulse who was trainable to direct traffic. Of course, this meant that every bad driver in Lexington knew that all bets were off in terms of speed limits, right-of-way, and other moving violations during those times. Ever read "Lord of the Flies"? Yeah, it was like that. With cars.
"This post contains words, known to the State of California to cause thought. Wash brain thoroughly after reading."
Let's just see you try that line on the police.
"I would have slowed down, officer, but it would have either taken too long or crushed me, so I didn't bother."
Being from Buffalo I was curious that I'd never heard of that - turns out it's actually in Syracuse, which is two cities east of Buffalo (Rochester in between) and about a two and a half hour drive :)
Here's some info,
And here's a photo.