I don't mean to wreck your day Noel but if you click on that link to that FRA Sander page and scroll down you'll see that it's right here on page #9907 Section B. Braking Distance They've conducted tests on this very question as to whether the application of sand helps or not and this is the official position of the FRA report. I know you have had years of experience with The New Haven and Conrail. there have also been lots of studies about this and what you have stated flies in the face of the FRA summary of the same thing. Again, perhaps everyone who wants to say well this or that worked for me should click on the link and read it. I'm not pointing the finger at anyone here, just stating the facts as described in this FRA document. Pg. # 9907 Section B. Braking Distance
As sanding may increase the coefficient of friction between wheel
and rail, one may anticipate that sanding can reduce the stopping
distance of a train from braking, especially on wet rail. However, the
following factors should be considered before drawing such a conclusion:
? The increase in friction is on the first few sets of axles
only (i.e., on the locomotives). Sanding will splash and be dispersed
rather quickly from the rails once several wheels roll over it. Over 90
percent of the wheels in a train will likely not receive any benefit
from sanding. Thus, it is unlikely that the stopping distance will be
affected by it.
? Wet rail and dirty rail can be dried out and cleaned out
rather quickly with the rolling of several axles on it. In numerous
field tests, the second locomotive's tractive effort is always 20-30
percent higher than the first unit, especially on wet rail. This is an
indication that the rail can be dried out and cleaned out just by one
locomotive passing over it. Therefore, wet rail conditions will only
affect one to two locomotives, and the rest of a train will be braked
on relatively dry conditions, even though the rails are originally wet.
Given the above explanation, sanding will hardly make any difference in
the braking performance of all the cars behind the locomotives.
? Engineers have been trained to rely on dynamic brakes
instead of the pneumatic brakes, unless during extreme emergency
situations. In emergency braking, little difference will occur in
stopping distance with or without sanding because, as explained
earlier, sanding likely only affects, if any, the braking efforts of
the first few axles.
? When insufficient adhesion prevails during braking, the
wheels may slide. The coefficient of friction during this sliding will
maintain the retardation rate of the trains.
Therefore, it is not surprising that the results of CN's testing
show that the emergency braking stopping distances under various speeds
and conditions were unchanged by sanding. However, the results of the
test of the stopping distances of a short VIA passenger train with and
without sanding were somewhat less expected. The conclusion for the VIA
test was the same as that for the freight trains. As the train consist
is very short for the passenger trains, typically as short as several
vehicles, the factors described above are not all applicable to the
passenger trains. It may be expected that some effect would occur on
the stopping distance of a passenger train as a result of sanding. The
vehicles in the tested passenger trains had mixed wheel and disk
braking, but it is not clear as to how disk braking is affected by
sanding. Nonetheless, the tests with VIA trains, submitted by the AAR
with the petition, showed that sanding had no effect in the stopping
distance of the trains. Even if sanding can affect the braking of these
short passenger trains, we should note that the stopping distance of a
short passenger train is extremely short compared to the heavy freight
trains, and therefore the actual difference in the stopping distance
will not be too significant. Some MU equipment always avoids sanding
because this equipment is light and the number of axles in a train is
usually small, thus, rail-shunting ability may get affected by sanding.
This is the primary reason why the MU equipment is not equipped with
sanders.
