"Freight car brakes are designed to the same ratio for empty cars. A 60,000 pound tare weight car with a braking ratio of 18% becomes a 263,000 pound load with a braking ratio of 4.1%. That is why freight trains take so long to stop. Most railroads show “tons per operative brake” on their consist and require that the engineer be told what it is. The empty is 30 TPOB while the load is 121. Engineers are fully aware of how trains with different TPOB ratios should handle but most pay close attention to how a new train responds to the first two or three applications they make to be sure that that they get is what they expect.
Mac"
My opinion is that the freight car brake design described above is the single most serious safety issue in railroading today. It means that a fully loaded freight train has almost no braking capability (less than 25% of what it might have with an improved design).
The reason to have low braking ratios is to avoid expensive wheel damage due to wheel lockup. I recognize this as a valid concern. But my recollection is that antilock brake systems (ABS) first appeared on New York subway cars back in the 1970s and that today nearly all rail passenger cars have ABS. Today ABS is standard equipment on most automobiles, but it has not appeared on railroad freight cars.
Another major safety defect is the inability to make a partial release of freight car brakes. This defect has caused a great many serious accidents over the years.
The railroads should have improved the freight car brake design decades ago, and (in my opinion) are negligent for not having done so.
I’ll admit that recently we have seen addition of load detectors on some freight cars to adjust the brakes for empty/full conditions, but this is a very primitive first step that should have happened decades ago.
ABS on freight trains? Oh please!! that would require a source of electricity, which there is none. It would require a separate brake system for each axle. And a LOT of maintainance. One axle failure could cause a catastrophe.
I remember in the early seventies the first attempts to put ABS on trucks. It actually caused accidents because when it detected a wheel locking it released all wheels for one revolution. One revolution of a truck tire is over 12 feet, with no brakes. They were a maintenance nightmare, (one fleet manager saying" they want me to maintain delicate electronics in a place where I can’t even keep paint") and were eventually removed. Yes 30 years later we do have workable systems. But you are claiming this should have been on railcars for years.
"The cost would have been a small fraction added to the cost to overhaul a freight car "
Most railcars never see an overhaul in their working lives, in fact most never see a second coat of paint. They are maintained on as as required basis. Their long life is due to simplicity and commonality of parts.
Such changes cannot be taken lightly. To change something of this nature means every piece of rolling stock in 3 countries, one of which can’t keep a cop alive for a month.
See also the explanation of “Load/Empty Sensors” on Al Krug’s "Air brakes’ page at - http://www.alkrug.vcn.com/rrfacts/brakes.htm#loadempty I have no idea of what % of cars in the fleet are equipped with those, though.
The current (since fall 2007) trials of Electronically-Controlled Pneumatic brakes (“ECP”) by BNSF, NS, and UP are a major step forward to address the problems that you identify. See the FRA’s PowerPoint-type briefing presentation on ECP brakes of August 2006 at: http://www.fra.dot.gov/downloads/safety/ecp_overview3a.pdf Some interesting approaches, statistics, and information are in there - such as Quebec Cartier has been running its iron ore trains with them since 1997 ! For lots of practical reasons - as identified in the FRA presentation - the implementation just needs to be gradual, starting with certain “closed” or “captive” high-mileage traffic, and broadening out from there.
In the end, this change-over/ upgrade won’t be like to Janney couplers or the Westinghouse air brake system - instead, it will be more like roller bearings on freight cars, shelf-type couplers, and some other equipment changes that had big ‘backwards compatibility’ problems with ‘legacy’ equipment. It will occur - probably over 20 - 30 years in total, or a typical ‘generation’ of rail rolling stock service life, before all significant equipment has been built new with it or converted. Then, we’ll look back and wonder what life was li
Increased ridership (longer load and unload times).
“By the book” operations. (By that I mean nowadays everything has to be done so exactly correct according to the rules and policies.)
For example; In the old days, the conductor on CNW suburban trains had the option of using a buzzer to indicate to the engineer that it was ok to proceed to the next station, rather than waiting for each door of the train to close (which would give the engineer an indication in the cab informing him to proceed). By using the buzzer, a conductor could save 5-15 seconds per stop; of course, if someone or something was blocking a door from closing, the train would still proceed, leaving the person (or luggage) exposed to the right-of-way. However, 99% of train crews that used the buzzer only did so when there was a crewman at each door to ensure no problems with open doors would happen. Those 5-15 seconds don’t sound like much, but when each trip consisted of 22+ stops, the time savings added up.
It is also true that some just didn’t care, and some were not taught right.
I have a copy of CRI&P’s Rules and Instructions Governing Employees in the Operation of Train Air Brakes and Air Signal, Effective August 1, 1955.
Under Passenger Train Handling, part of Rule 48 (Stopping from High Speeds) reads:
"D. Diesel locomotives, throttle must be left in throttle position in which you are working before initial application; as speed decreases, throttle must be reduced accordingly, keeping train slack stretched, then commence to graduate off the brake by moving the brake valve handle momentarily to running position and then to lap.
E. Further graduations should then be made by moving the brake valve handle from lap to running position, and back to lap. Make the stop with low brake cylinder pressure."
Further on in there is a section that states: “Do not attempt graduated release unless at least a fifteen pound total brake pipe reduction has been made.”
I found a rule that states passenger car triple or control valves must be set to direct release (instead of graduated release) position when handled in freight trains over 20 cars or in trains handling both freight and passenger cars over 20 cars. I haven’t found a limit for trains handling only passenger equipment.
The early CNW Metra units that I had experience on (the unit numbers were from 101 up to somewhere around 140) had a system that whenever the train was in braking mode (air set), the blended brake would stay in ‘brake’ mode, even when stopped.
When operating from the locomotive, this design was no problem, because usually when stopped, the independent is set and the train brakes are released, and the BB mode would quickly revert to power (after giving the throttle a quick nudge to ‘1’ and then back to ‘idle’) and stay there for the duration of the stop. When operating from the cab-car, this design was a pain-in-the-posterior.
Back before Metra modified the cab-car parking brake, the parking brake exhausted into the cab; this was extremely loud and frequently contained drops of oil and alcohol, so we didn’t use it–instead, we would sit at the station with the train brakes set. Of course, in the days of F7 & E8 power, keeping the brake set was necessary due to the quick loading of the units. Starting a train from the cab-car without at least 30psi on the trainline brakes was a guaranteed way to spill much co