Air Brakes on Trains

From what I've heard this was an auto piloted train with the brakes disabled....

The principe of the continuous automatic air brake is that air pressure is needed to release them. Once released, a reduction of air pressure in the train brake pipe causes the brakes to be applied and the train to come to a stand. The reason for this is so that, in the event of the train becoming divided into more than one portion, both parts will come to a stand.

In order for this to work, there has to be some way of applying the brakes with the divided portion not connected to the locomotive(s). The way this is done is to have an air reservoir on each vehicle arranged so that it is charged up from the locomotive(s) compression equipment via a non-return valve so that, in the event of the train becoming divided into more than one portion, the reservoir contains sufficient air to apply the brakes and bring that portion to a stand.

All sorts of things can cause a train to run away. For an air-braked portion not connected to working compression equipment the most likely possibility is the non-application of the hand-brakes on the vehicles in that portion and gradually, over a period of time, the air in the reservoirs to leak away, leaving no force left with which to keep the brakes applied.

The arrangement of tracks in yards is also of interest. If the yard is level or a falling gradient towards a running line, it is usual to arrange for some form of trap point arrangement to prevent unbraked vehicles that are out of control in the yard to come into conflict with other movements on running lines and divert them somewhere they can be brought to a stand without using the on-vehicle brakes.

There is always something to be learned from any incident, and the activities of those investigating are a topic of great interest.

No, it isn't a contradition:

http://en.wikipedia.org/wiki/Westinghouse_Air_Brake_Company

Like others, I'm still confused! I did read the article of your link, but I can't say I understood it fully.

I too have always assumed that train car brakes were "spring on, air off". I must confess that I had never thought about the need for more-or-less simultaneous application of the brakes in all cars when moving, but it seems so obvious that loss of air pressure should apply the brakes.

The Wiki article did mention that the original design left the cars without brakes if air pressure was lost. I do understand that later improvements gave each car its own air tank (that much I've observed, but never really gave it much thought), but it still seems like any failure (tank rupture, hose rupture, loss of engine power,...) should intrinsically apply the brakes. Does it?

Aaaah.

Interesting. I'd assumed that train air brakes were the same as truck air brakes, where lack of or loss of air pressure means the brakes will apply.

Learn something new every day...

It looks like corners were cut, regulations ignored and probably poor maintenance.

In the news it says now that a criminal investigation was launched!

Does look like there is even more to it!

Debate point: is making an honest mistake a criminal offence?

http://en.wikipedia.org/wiki/Thirsk_rail_crash_(1892)

criminal negligence....

Judge I thought I could get away with it.....it was an honest mistake.....

Aren't there any parking brakes?.

If the engine/compressor is left running with the train stopped air will leak the system up. It is the same air that one must occasionally bleed when the train is underway. But that is on old engines.

When the train is stopped and the engineer prepares to walk away the air is bledout and the air is un coupled from the entire train. To move the train agaian one must build up air.

This was no accident.

This kind of makes sense now! The air release in the system is manually activated. Its as they say the "Handbrake" that was not pulled/air not released.

OMG!

All,

Your points of confusion indicate that the reporters covering the story don't know ANYTHING about how trains, and braking systems work.

This was also obvious to me when Flt 214 crashed last week.

It's also obvious whenever I read stories about gun control (not hitting the intended target, but legislation) or even guns themselves.

In fact, This seems to be more or less true across the board.

I thought diesel electric locomotives have a 'deadman' switch so they are locked down with no operator...I read the 'engineer' was in a motel, who was at the switch?

Not to confuse things but to provide some information that I read in various railroad sources and Emergency responder sources I would like to provide some information:

"Progressive Railroad" states that there were five locomotives and they derailed. It didn't state whether they were at the rear or front of the train, engines running, whether the extra units were operating as one unit, idling, shutdown? Were the air brakes applied, car manual brakes applied (hand wheels on the "B' end of a car), derailers in place on the track, etc.

Were the engines idling, shut-down, etc.?

Applying the brakes at the locomotive cab doesn't necessarily make the train unmovable. One possibility is that the locomotive valve could have leaked through and increased the air pressure in the brake line. Many others are possible (as per a member of the Conrail safety staff).

There was a fire on the train involving possibly the brakes earlier that day. Only information given on this was they didn't know if this was a factor.

Air brakes are not infallible. When a train is spotted, especially if it will be unattended, the crew will put the hand brakes on an appropriate number of cars. Longer train means more hand brakes applied. Was this done?

Vandalism? When I was a kid some trouble makers got into a cab of a train and moved as many controls as they could. Result was two engines and six passenger cars going through a switch and going into a lumber yard siding. The two engines and two of the cars landed on their side with two more derailed. An unattended train would certainly be a good candidate. Fortunately or unfortunately the kids jumped off when it started to move so they were not hurt.

Perfectly prepared trains have gone out on their own in the past. Approx. 10 years ago in Northwestern Ohio, a train somehow started moving on it's own. It's speed increased to 40 to 50 mph headed down towards the Columbus area. Fortunately, and with a lot of guts, personnel on the ground and in another engine were able to approach the runaway and couple onto it. It was noted that there were difficulties in stopping it because the brakes on the rescue engine were getting extremely hot to the point that the rescue crew expected them to fail. A movie was later made bases on this incident. It was supposedly based in the Scranton, PA, area (Northeastern PA). I think the movie was titled "Runaway" or something similar to that. The movie was based on facts, not a script writers HO layout. I think one of the actors was Danny Glover (spelling?)

If you would like to obtain more information on the Canadian incident search the railroad magazine trade sites such as "Progressive Railroading", National Transportation Safety Board (NTSB) although this was in Canada, the railroad that the incident occurred on, newspapers local to the incident (first hand observation vs. the national wire services), Canadian gov't applicable web sites, first responder web sites such as "Firehouse" and "Fire Engineering, web sites for the local fire depts., etc. They often have bulletins about larger incidents especially one of the magnitude of this one. The information is out there and more plentiful the harder you look.

Good Luck, Old Salt

I just found some interesting information concerning runaway trains in Canada. Not to be critical but they have averaged approx.. one incident of this type per year since 1994. Some years there were two of these accidents. The information is available from the Transportation Safety Board of Canada. The rail accident reports are available at:

http://www.tsb.gc.ca/eng/rapports-reports/

Go to:

http://www.tsb.gc.ca/eng/rapports-reports/rail/index.asp

and do a search for a particular type of accident. I entered "runaway" and got 16 matches. This clearly shows that this type of accident is not as rare as we may have thought.

If anyone wants some additional knowledge on the subject give it a try and read or skim the reports.

Good Luck, Old Salt

From Wikepedia:

"...Limitations

The Westinghouse air brake system is very trustworthy, but not infallible. Recall that the car reservoirs recharge only when the brake pipe pressure is higher than the reservoir pressure, and that the car reservoir pressure will rise only to the point of equilibrium. Fully recharging the reservoirs on a long train can require considerable time (8 to 10 minutes in some cases^[5]), during which the brake pipe pressure will be lower than locomotive reservoir pressure.

If the brakes must be applied before recharging has been completed, a larger brake pipe reduction will be required in order to achieve the desired amount of braking effort, as the system is starting out at a lower point of equilibrium (lower overall pressure). If many brake pipe reductions are made in short succession ("fanning the brake" in railroad slang), a point may be reached where car reservoir pressure will be severely depleted, resulting in substantially reduced brake cylinder piston force, causing the brakes to fail. On a descending grade, the unfortunate result will be a runaway..."

http://en.wikipedia.org/wiki/Railway_air_brake

It will be interesting to see what the "Official Report" has to say.

I would like to share the partial content from a recent article from a "Fire-Rescue Newsletter" article.

Rail boss points finger at firefighters in deadly runaway train explosion

Investigators are focusing on the train's brakes, the railway company's own regulations and whether they need tougher train-transport standards

.....................The same train caught fire hours earlier in a nearby town, and the engine was shut down - standard operating procedure dictated by the train's owners, Nantes Fire Chief Patrick Lambert said.

Edward Burkhardt, president and CEO of the railway's parent company, Rail World Inc., suggested that shutting off the locomotive to put out the fire might have disabled the brakes.

"An hour or so after the locomotive was shut down, the train rolled away," he told the Canadian Broadcasting Corp.

Lambert defended the fire department, saying that the blaze was extinguished within about 45 minutes and that's when firefighters' involvement ended.

"The people from MMA told us, 'That's great - the train is secure, there's no more fire, there's nothing anymore, there's no more danger,'" Lambert said. "We were given our leave, and we left."

Transportation Safety Board investigator Donald Ross said the locomotive's black box has been recovered.

"The extent to which (the fire) played into the sequences of events is a focal point of our investigation," Ross said, but he cautioned that the investigation was still in its early stages.

The accident has thrown a spotlight on MMA's safety record.

Before the Lac-Megantic accident, the company had 34 derailments since 2003, five of them resulting in damage of more than $100,000, according to the U.S. Federal Railroad Administration.

Burkhardt said the figures were misleading.

"This is the only significant mainline derailment this company has had in the last 10 years. We've had, like most railroads, a number of smallish incidents, usually involving accidents in yard trackage and industry trackage," he told the CBC.

The tanker cars involved in the crash were the DOT-111 type - a staple of the American freight rail fleet whose flaws have been noted as far back as a 1991 safety study. Experts say the DOT-111's steel shell is so thin that it is prone to puncture in an accident, potentially spilling cargo that can catch fire, explode or contaminate the environment.

The derailment also raised questions about the safety of Canada's growing practice of transporting oil by train, and is sure to bolster the case for a proposed oil pipeline running from Canada across the U.S. - a project that Canadian officials badly want.

found this graphic that helps to explain the train accident. With a good graphic on train air brakes operation.

Also a link to Train Order has quite a lot of info, and a lot other train stuff.