Railway Engineering 5

Railway Signalling System Railway Engineering-5

Railway Signals • Objectives: – Efficient movement of trains – Ensuring safety of trains moving on crossing tracks – Maximum utilization of track – Safety during shunting operations – Managing train movement during maintenance and repairs

Signals Classification • • • •

Based on Operating characteristics Based on Functional characteristics Based on Locational characteristics Based on Special characteristics

Operational Classification Operation Audible

Visual Hand Operated Fixed Installation

Operational Classification (ctd…) • Audible Signals – Detonators – Used during low visibility conditions – Fixed to the rails – Detonates as the train passes over them – Paced 400 to 500m before the signal

Operational Classification (Ctd..) • Visual Signals – Hand Operated • Operated using hands in many forms

– Fixed Installation • Placed on the top of the post • May be of movable arm type or colour light type or disc type • 1 or more Nos. placed on the same post

Functional Classification Function

Hand

Flag

Light

Fixed

Hand Indicator

Stop

Warner

Functional Classification (Ctd…) • Using Hand – Flag, Red or Green colour – Light, Green, Red and sometimes yellow – Hand indications are used mostly on Shunting Operations – Used by Station masters, Guards, Gang man, Cabin man, Point man, etc..

Functional Classification • Fixed Signals – Stop Signals – Warner Signals – May be of movable arm type (SEMAPHORE) or colour aspect type – Indicates stop condition, caution condition, respectively – These are operated using electric current, or wires or keys.

SEMAPHORE SINGAL • SEMAPHORE STOP SIGNAL – Consists of the following • Movable arm • Spectacle, holding two colour glasses • Lamp for light indication • Crank rod, cam, lever, and counter weights • Signal post • Chain and Pulley • Wire to cabin

Colour Aspect Signal • Semaphore signals are replaced by colour aspect signals on electrified tracks. • High intensity colour beam focused at eye level of driver is used. (Visible in day and night as well) • Used for heavy traffic, urban and sub urban tracks • Sometimes two yellow lights are used having a meaning that Pass with full speed but be prepared to caution for the next signal.

Warner Signals • Indicating caution • Provided with a V-notch at the free end and V band. • Yellow in colour with a white background. • Can be placed separately on a post or in combination with a SEMAPHORE SIGNAL

Locational Classification

Location

Reception

Outer

Home

Departure

Starter

Routing

Advance Starter

Shunting

Locational Classification • Reception – Signals which control the reception of trains into a station. – Outer Signal: First stop signal before the entry from block section to station section • Placed at some specified distance from the station limit. (Usually 0.5 Km )

– Home Signal: Signal provided at the door of the station section. (Last opportunity to stop the train before they finally accommodated to a particular platform)

Locational Classification • Departure Signals: – Starter Signal: • Mark the limit upto which the train stopping at a station should come to a stand. • Separate for each line

– Advance Starter Signal: • These are last stop signals on station limits

Locational Classification

Locational Classification (Ctd…) • Routing Signals: – Depends upon the number of lines existing on the station. – This signal indicates the track for which points are set.

Shunting Signals • Used for shunting operation in the station yards • Where semaphore signals are provided, these signals are provided in disc shape. – Disc is provided with a red band on white background – Provided with two holes, one for red light and other for green. – It revolves in a vertical plane – When red band is horizontal or it is indicating red light during night then it is STOP condition.

Classification based on Special Characteristics • Repeater Signal • Co-Acting Signal

Repeater Signals • Provided when a signal is not visible to the driver from adequate distance due to curvature. • This may be semaphore type or colour aspect type • It is provided with “R” marker

Co-Acting Signal • Provided when a signal is not visible to the driver due to some obstruction such as over bridge, high Structure etc., • Placed preferably on the same post and is exact replica of the original signal.