Isolation means making a railway line or track completely safe before carrying out any maintenance, repair, or engineering work. The purpose of isolation is to ensure that no train, vehicle, or rolling stock can accidentally enter the working section.
Isolation is applied by adopting approved methods so that even by mistake no train or vehicle can reach the work site. Through isolation, protection is provided to the staff working on the track.
Means of Isolation
- Setting of Points
- Trap Point
- Permanent Locked Point
- Sand Hump
- Dead End Siding / Snag Dead Siding
- Hay Drill
- Scotch Block
- Derailing Switch
(1) Setting of Points
Isolation is achieved by correctly setting the points so that the route towards the working line is not available. The points are set away from the work site and secured.
Explanation
Correct setting of points ensures that trains are guided to a safe line and cannot enter the isolated section.
(2) Trap Point
A trap point is provided on a siding or loop line to protect the main line. It diverts or derails any vehicle that moves unintentionally.
Explanation
Trap points are a vital safety device to prevent runaway vehicles from fouling the main line or work area.
(3) Permanent Locked Point
A permanently locked point is a point which is secured by an approved locking arrangement and cannot be operated without authorization.
Explanation
Permanent locking ensures that the point position cannot be altered accidentally or by unauthorized staff.
(4) Sand Hump
A sand hump is a raised portion of track filled with sand. It is designed to stop or derail vehicles moving at low speed.
Explanation
Sand humps absorb the kinetic energy of a moving vehicle and prevent it from reaching the work site.
(5) Dead End Siding / Snag Dead Siding
A dead end siding is a track that terminates without connection to any other line. A snag dead siding is specially designed to trap vehicles.
Explanation
These sidings safely contain vehicles and prevent them from entering running lines or isolated sections.
(6) Hay Drill
Hay drill is a temporary wooden or metallic obstruction fixed across the rail to stop or derail vehicles.
Explanation
It is mainly used during temporary works and provides visible and effective protection.
(7) Scotch Block
A scotch block is a block of wood or metal placed against the wheel of a vehicle to prevent its movement.
Explanation
Scotch blocks are simple but effective devices used especially on gradients to stop rolling stock from moving.
(8) Derailing Switch
A derailing switch is a special switch provided to deliberately derail vehicles moving in an unsafe direction.
Explanation
Though derailment damages rolling stock, it prevents serious accidents and protects human life.
Advantages of Proper Isolation
- Ensures complete safety of staff working on the track
- Prevents unauthorized or accidental train movement
- Minimizes risk of collisions and derailments
- Improves coordination between Engineering and Signaling departments
- Builds confidence and efficiency among workers
