The purpose of this guide is to provide my experience as well as advise on operating today's prototypical length trains in HO scale.Most modern railroads in North American have come to realize that train length is a significant factor in operating costs and providing maximum profits.Therefore in unit trains and typical freight trains train length is normally in the 100 + car number.The average car in todays trains is around 50 foot in lenght.This easily leads to train lenghts of  5000 to 6000 feet.In HO scale this means a train could be 63 feet or longer if it is ran in prototypical fashion.
    My experience as been in operating HO scale trains of this lenght on my home layout as well as the club layout that I belong to.My most extensive experience is with the club's layout, which at a maximum size is 24 feet in width and 56 feet in length.This layout is a modular layout that is set-up  for limited amounts of time and in different settings.We have operated this layout at our own exhibits as well as at fairs,other clubs train shows,GATS events and for special charity events.It is important that we try to have well functioning and operating trains so that the puplic can see in scale, what passenger and freight operations are really like.The club's layout is primarialy straight and level,two mainline, six foot by two foot sections with  thirty six inch curves on the corner  modules.This provides a relatively easy track scheme in which to operate.
    My experience as been that in regards to the trains, two factors are very important in running theses types of trains.The first is to have compatible and modern locomotives.If your locomotives aren't functioning well or are incompatible in speed or operating modes you will have  a very difficult time operating any trains.I have operated most brands and types of modern diesel engines and I have found that most if not all will pull sufficiently to  be used in this type of service.The typical  power arrangement  I have used as been to use three or four of the modern six axle diesels to pull 100 car coal type unit trains.The most problems that I have experienced is that if you have a temporary lost of power to one or more engines you can have a very prototypical slack action which can lead to either derailments or train seperation.So clean wheels and track are very important in this situation.
    The second factor I have found that is very important is the type of car in your train.My experience has been primarily with Walther bethagon coal cars.Unforunately I couldn't use them as they were equipped from the box in this type if trains.I found that changing the wheel sets to metal wheels were very important, as well as changing the couplers to a metal  knuckle type coupler.The reason for this was that in operating practice I had found that if you did have any slack action,either due to engineer error or power problems that any plastic type coupler didn't with stand the strain from this so you would almost always would have a broken coupler and possible derailment.The metal wheel sets aided train operations in two ways.The first is in considerable friction reduction between the track and cars.The second is in reduction in track contamination by particles of plastic that are worn from the wheels.As most railroad enthusiaists know the cars and engine only stay on the track by the action of the wheels flange against the rails of the track.In this process when a train goes around a curve there is an action called  stringlining in which the tractive force attempts to force the train into a stratight line.Even in HO scale with a long train this can lead to considerable friction and wear on the inside wheels in a curve.To reduce this metal wheels are the best solution.The last important factor in the cars is car weight.The is a double edged sword in that heavier cars adhere to the track better but heavier cars of course add to total train weight.It is important to have cars that conform to the NMRA standards or are at least close.The Wathlers coal cars about !/2 ounce light empty but this is close enough to have reliable operation.The worst situation is to have cars that are too light.Invariably when the train is in a curve these cars are  unable to withstand the lateral forces and fall over.Even properly weighted  cars will do this if terrain or  scenery obstruction stops the rear of the train.
     In conclusion I have found that running prototypcal lenght trains can be done on layouts of sufficent size and is very impressive for any spectators.Of course moderate speeds and conservative operations are advised.I must admit that when things go wrong with this size train it can be very messy and time consuming to rerail and cleanup, but I do find that the appreciation of spectators and your fellow scale railroaders makes the effort very worthwhile.If anyone has comments or further questions please email me at xswordsman through ebay.Thank you.