The window of a train is more entertaining than TV - Kirti Solanki

Ground level signs on a concrete slab base, with a number and an upward or downward pointing arrow, indicating a grade. A number '500', for instance, indicates a grade of 1 in 500. Black on white.
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The arrow is often simply a 'v'-shaped mark instead of a full arrow symbol. A similar sign without an arrow and an 'L' instead of a number indicates the end of the grade.
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There are some newer gradient or incline warning signs that are not on the ground as the ones described above but fitted to poles or catenary masts. They are usually yellow with blue or black arrows (although some blue signs with white arrows have been seen) with reflective paint, indicating upward or downward gradients; a double-headed (bidirectional) arrow is used to indicate a level section. The difference between these and the ones described above is that these are placed about 500m-700m in advance of the gradient they refer to, whereas the conventional grade indicators described above are placed at the point where the gradient or level section begins. The gradient indicators on catenary masts are also often accompanied by signs advising drivers to power up for the gradient.
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Courtesy: IRFCA