The number of vehicles you put behind a locomotive depends a lot on the size of your layout. The larger it is the more you can add without it looking ridiculous.

A useful rule of thumb for calculating speeds is that one foot per second, actual, is almost exactly sixty scale miles per hour, or perhaps easier to measure ten feet in ten seconds. Actual speeds reached depends both on era and prototype but it is worth remembering even modern trains accelerate quite slowly compared to say a motor vehicle. It is also worth remembering ,keeping the speed down is one way of making your layout look larger. Most people tend to accelerate to quickly and run to fast. Apart from expresses and modern container trains, typical speeds might be up to sixty for a passenger train and half that for goods with the average speed being a lot less.

Bob M.

As Bob said, the number of coaches depends on the size of your layout. You specifically mentioned the Crocodile, which was used in Era II and Era III. During those periods, short two axle freight cars were the norm, so a train would have many more cars than a modern freight train using four axle bogie cars. As far as passenger cars, the maximum length of an international train in Switzerland and Italy was 14 (26,4m) coaches. This limit was determined by the length of station platforms and tracks in most stations where the train was scheduled to stop.

If you are using 30 cm (1/87 exact scale length) coaches, you will probably have to limit your train to four to seven coaches
If you are using 28 cm (1/93) coaches, you will probably still have the same limit
If you are using 27 cm (1/100) or smaller (24 cm) coaches, you may be able to add one extra coach to the consist.

If you are using freight trains, use the length of an average passenger train as a guide to see how many freight cars take up the same length.

Regards

Mike C