As the speed is increased, the relative effect of grade and curves is lessened, but the absolute danger of passing curves is increased. Express trains require larger radius of curvature, or greater elevation of exterior rail than others, which extra elevation causes an unnecessary resistance to all other trains. The rails to resist large and heavy wheels must be heavier and more firmly fastened. All bridges and viaducts (particularly if on grades or curves), will require more strength to resist the increased shocks to which they will be subject. The wear of rails is nearly as the weight passing over them; the wear of rails consequent upon stopping and starting the trains depends upon the momentum of the train which is to be imparted to them.
The proportion, in which the working expenses are distributed under the several heads on the larger railways of Great Britain, is as follows:—
| Direction and management, | 7 |
| Way and works, | 16 |
| Locomotive department, | 35 |
| Cars, | 38 |
| Sundries, | 4 |
| 100 |
And the percentage of increase due to fast travelling, to be applied to the several items of expense, with the resulting increase in total expense, is shown below.
| Direction and management, | 7 | 0 | = | 0.0 |
| Way and works, | 16 | 27 | = | 4.3 |
| Locomotive department, | 35 | 30 | = | 10.5 |
| Cars, | 38 | 10 | = | 3.8 |
| Sundries, | 4 | 0 | = | 0.0 |
| 100 | 18.6 |
or 18 per cent. increase, nearly.
Express trains, as worked on many roads, run at an unnecessary speed, to make up for frequent stops. Overcoming a long distance in a short time, depends as much on decrease in the number of stops, as increase in the speed.
The following figures show the effect of decreasing the number of stops.
A train running 400 miles, and stopping once in fifty miles, each stop being five minutes, (including coming to rest and starting,) to pass over the whole distance in eight hours, must run fifty-five miles per hour.
Stopping once in twenty miles, sixty-three miles per hour.