Fouling Mark

A fouling mark (Fig. 27.12) is provided between two converging tracks at the point beyond which the centre-to-centre distance of the track is less than the stipulated minimum distance. This minimum distance is 4.265 m for BG and 3.66 m for MG lines. A vehicle standing on a loop line is not stabled beyond the fouling mark, otherwise it may have a side collision with the vehicle standing on the main line. The salient features of a fouling mark are as follows.

Fouling mark
Fig. 27.12 Fouling mark

(a) A fouling mark consists of a stone or concrete block or an old wooden or steel sleeper painted white.

(b) The fouling mark should be visible from a distance. Therefore, it is painted white and has the letters FM marked on it in bold using black paint.

(c) The top of the fouling mark should be in line with the top of the ballast section.

(d) The fouling mark should be fixed firmly on the ground at right angles to the track.


Several types of equipment are needed at a railway station to ensure the safety of the railway system. These equipment are required for the convenience of passengers at stations and for handling goods in yards. The yards are also equipped with other facilities such as locomotive sheds, ashpits, and turntables. The safety and efficiency of a station are greatly influenced by the quality of these equipment.

Review Questions

1. What are the various devices and equipment used in station yards?

2. What is a turntable? In which railway yard is this located? Explain its function.

3. Give a list of the equipment required by an ordinary railway station.

4. What are the essentials of a well-laid locomotive shed? Describe with the help of sketches the layout of locomotive sheds on Indian Railways.

5. What is the difference between ashpits and ash pans? Draw a sketch showing the details of an ashpit.

6. Write short notes on (a) turntable, (b) ashpit, (c) loading gauge, (d) fouling mark, (e) derailing switch, (f) locomotive shed.

7. Write short notes on (a) marshalling yard and (b) turntable and triangle.


Scotch Block, Derailing Switch, and Sand Hump | RAILWAY ENGINEERING - Contents | Construction of New Railway Lines and Track Linking