Since most of our yards are still equipped with the 3 class lights... many of the crews (especially those running beltpack) feel the need to put some combination of them on... a few of the units have the controls removed, or broken off... and many of the bulbs are burned out (and we don't bother replacing them...)... so they're not working as well as some of the crews may like them to..
FYI,
If you want to see an example of the rules governing this type of thing, the GCOR rules (at least a year 2000 vintage copy) are available here : http://gsee.sdf-us.org/signals/docs/pdf ... 4-2000.pdf
The relevant rule is 5.10.
(our rule book says pretty much the same exact thing, except for us it's rule 15; I think ours are based on CSX)
- litz