Railway stations can broadly be sorted into various classes on the basis of two main considerations.
As per the general and subsidiary rules of Indian Railways stations are classified as block stations and non-block stations. Block stations are further classified as A class, B class, and C class stations. Non-block stations are classified as D class or flag stations.
Stations are classified based on the functions they are required to perform. Under this category, stations are classified as halt stations, flag stations, crossing stations or wayside stations, junction stations, and terminal stations.
The following factors are taken into consideration when classifying a railway station.
(a) Least expenditure with regard to the provision of the least number of signals
(b) Flexibility in shunting operations
(c) Increasing the line capacity
(d) Faster movement of trains
A block station is a station at which the driver has to obtain an 'authority to proceed' in order to enter the next block section. In a railway system that is inclusive of block stations, the entire railway line is divided into convenient block sections of 5 to 10 km and a block station is provided at the end of each block. This system ensures that a suitable 'space interval' is provided between running trains so that there are no collisions and accidents. There are three types of block stations.
A class station
A class stations are normally provided on double-line sections. At such stations a 'line clear' signal cannot be granted at the rear of a station unless the line on which a train is to be received is clear and the facing points set and locked. No shunting can be done after line clear has been granted.
A class stations are suitable for sections where traffic passes rapidly. It is essential for the driver of the train to have an advance knowledge of the layout of the block station. The typical layout of an A class station with two-aspect signalling is shown in Fig. 26.1.
Fig. 26.1 A class station
The signals required at an A class station are as follows.
Warner A wamer signal is placed at a warning distance from the home signal, the main function of which is to indicate whether the section beyond is clear or otherwise.
Home A home signal, which is the first stop signal.
Starter A starter signal is placed at an adequate distance from the home signal and marks the point up to which the line should be clear so that the train can be given permission to approach.
Advance starter This signal is optional and is provided to allow the drivers to further increase the speed of the trains.
(a) More economical vis-a-vis B class stations because of the use of fewer signals.
(b) Ensures the safety of the train because of the provision a warner signal ahead of a home signal.
(c) Trains normally stop within the station limits.
(a) No shunting is possible once line clear has been granted.
(b) Another clear disadvantage of A class stations, is that a line at the station has to be kept clear up to the starter signal once the line clear signal has been given, and as such the flexibility of working and shunting is restricted.
B class station
This is the most common type of station and is provided on single-line as well as double-line sections. At a B class station (Fig. 26.2), the line has to be clear up to an adequate distance beyond the outer signal before 'permission to approach' can be given to a train. The minimum signals required at a B class station are as follows.
Outer An outer signal, which is the first stop signal. The outer signal can also be below the warner also.
Home A home signal, which protects the facing point and is placed at an adequate distance from the outer signal.
Starter A starter signal is also provided on a double-line section.
The B class station is the most common station in use on Indian Railways because it offers greater flexibility of working. By providing a warner on the outer arm post, this station can also cater to fast traffic while permitting shunting of vehicles even when a clear signal has been given.
C class station
The C class station (Fig. 26.3) is only a block hut where no booking of passengers is done. It is basically provided to split a long block section so that the interval between successive trains is reduced. No train normally stops at these stations. The minimum signals required are as follows.
Fig. 26.3 C class station
Warner A warner signal placed at an adequate warning distance from the home signal to indicate whether the section ahead is clear or not.
Home A home signal, which is the first stop signal.
The advantage of a C class station is that it ensures the faster movement of trains and increases line capacity. The disadvantage, however, is that no shunting is possible and trains cannot stop at these stations.
26.5.2 Non-block Stations or D Class Stations
D class or non-block stations are located between two block stations and do not form the boundary of any block section. No signals are provided at D class stations.
A D class station that serves an outlying siding is called a DKstation. At such a station, the siding takes off through a crossover, which can be operated only with the help of a key, which in turn is released with the help of a ball token. A D class station that serves no siding is called a flag station.
Functional Classification of Stations
The layout of stations varies in size and importance according to the type and volume of traffic handled and according to their locations with respect to cities or industrial areas. Broadly speaking, the layouts required for passenger stations and their yards can be divided into the following categories for the purpose of study.
(b) Flag stations
(c) Roadside or crossing stations
(d) Junction stations
(e) Terminal stations
A halt (Fig. 26.4) is the simplest station where trains can stop on a railway line. A halt usually has only a rail level platform with a name board at either end. Sometimes a small waiting shed is also provided, which also serves as a booking office. There is no yard or station building or staff provided for such types of stations. Some selected trains are allotted a stoppage line of a minute or two at such stations to enable passengers to entrain or detrain. The booking of passengers is done by travelling ticket examiners or booking clerks. A notable example of the halt is a Gurhmukteshwar bridge halt, which is situated on the bank or river Ganga.
Fig. 26.4 Layout of a halt station
A flag station (Fig. 26.5) is more important as a stop-over for trains than a halt and is provided with a station building and staff. On controlled sections, a flag station is equipped with either a Morse telegraph or a control phone, which is connected to one of the stations on either side to facilitate easy communication. A flag station is usually provided with a small waiting hall and booking office, platforms and benches, and arrangements for drinking water. Sometimes a flag station is also provided with a siding for stabling wagons booked for that station.
Wayside or crossing station
After a flag station comes the wayside or crossing station. While a flag station has arrangements for dealing with traffic but none for controlling the movement of the trains, a crossing station has arrangements for controlling the movement of trains on block sections. The idea of a crossing station was initially conceived for singleline sections, to facilitate the crossing of trains going in opposite directions so that there may be a more rapid movement of trains.
Fig. 26.5 Layout of a flag station
Crossing stations may be further classified as (a) Roadside small- and mediumsized stations and (b) Major stations. Some of the important tasks dealt with these stations are the following.
Operating work The main operations performed at these stations include attending to the passing and crossing of trains, giving precedence to important trains, and other miscellaneous works done for stopping passenger trains. Slow passenger trains mostly stop at small stations whereas mail and express trains stop at major stations.
Goods traffic These stations mostly deal with parcel traffic only. Piecemeal wagon load goods traffic is now being accepted on roadside stations as per the new policy of the Railway Ministry with effect from December 1994.
Operation of points and signals The operation of points and signals is controlled either by a central cabin or two cabins at either end of the station.
Reception and dispatch of trains The reception and dispatch as well as shunting of trains is handled as per the instructions laid down in the 'station working order'. Block instruments are provided either in the station master's office or in the cabin, but the entire responsibility of carrying out these operations lies with the station master.
Station master's duty for run-through trains When a train runs through the station, the station master should stand opposite his office in proper uniform and exchange 'all right' signals with the driver and guard of the train. He should watch the running train carefully and if there are any unusual occurrences such as the incidence of a hot box, he should instruct the station officials in advance to stop and examine the train.
Wayside or crossing station on a single-line section Increasing traffic on a singleline section necessitates the construction of a three-line station, which provides an additional line as well as more facilities for passing traffic. A typical layout of a three line station providing one additional line and simultaneous reception facilities is given in Fig. 26.6. It may be possible to improve the facilities further by introducing an additional line to deal with goods traffic.
The following are some of the important features of this track layout.
Fig. 26.6 A wayside or crossing station on a single-line section
(a) It is a three-line station and provides facilities for the simultaneous reception of trains from both sides because of the proximity of sand humps in each direction.
(b) There are two platforms, namely, an island platform and a platform near the station building. The island platform can deal with two stopping trains simultaneously. Also, if a goods train has to be stopped at an island station, it can be accommodated on the loop line of the platform, thus keeping the main line free for run-through traffic. Important trains can be made to halt on the platform near the station building.
(c) There is a dead end siding at either end of the station to accommodate wagons that are marked sick.
(d) The foot over bridge (FOB) helps the passengers to reach the island platform from the station building and vice versa.
Double-line crossing station with an extra loop In the case of a double-line section, which consists of separate up and down lines to deal with traffic moving in either direction, the layout of a station yard is somewhat different.
Figure 26.7 shows a double-line station with three lines receiving, with one common loop for trains coming from both sides. Some of the important features of this layout are as follows.
(a) This is a wayside station for a double-line section with almost minimum facilities.
(b) In addition to two main lines an up line and a down line, there is a common loop that can receive trains from either direction. There is a total of three lines only.
(c) It consists of two platforms, one an island platform and the other a platform beside the station building.
(d) There is a foot over bridge to connect the station building to the island platform and back.
(e) There are emergency crossovers provided on either side of the station so that it can be converted into a single-line station in the case of an emergency.
Double-line crossing station with four lines The more common layout of a station yard on a double-line section has four lines station as shown in Fig. 26.8. The important features of this layout are as follows.
(a) This is a four-line station, where, apart from two up and down main lines, there are two extra loops. These loops are directional loops, i.e., one is known as a down loop as it is meant for down trains while the other is an up loop and is meant for up trains.
(b) There are two platforms provided with connection loops. One of these platforms can also be an island platform.
(c) There is provision of a foot over bridge to connect the two platforms.
(d) Two emergency crossovers are provided on either side of the station so that is can be converted into a single-line station in the case of an emergency.
A junction station is the meeting point of three or more lines emerging from different directions. Normally at junctions, trains arrive on branch lines and return to the same station from where they started or proceed to other stations from where they again return to their originating stations.
The typical layout of a junction station with a single main line and a single branch line is shown in Fig. 26.9. The important features ofjunction stations are as follows.
Fig. 26.9 Junction station with single main line and single branch line
(a) There are two platforms-one is the main line platform and the other is an island platform. In case the timings of two trains match, both the trains can be received and made to wait on either side of the island platform. This helps in the easy trans-shipment of passengers and luggage. Also, main line as well as branch line trains can be received on the main platform.
(b) A foot over bridge is provided for passengers to move between the station platform and the island platform.
(c) It is provided with a small goods siding and a goods platform to deal with goods traffic.
(d) A turntable is provided for reversing the direction of an engine, if required.
(e) The emergency crossover on provided either side of the station helps in switching to a single-line set-up in the case of an emergency.
A few examples ofjunction stations are the Ghaziabad, Allahabad, Itarsi, Nagpur, and Jabalpur junctions. The typical layout of a junction station on a double-line section with one or two branch lines coming in from one or two different directions is shown in Fig. 26.10. The most important feature of this layout is that such a station receives traffic from four different directions, i.e., up main line, down main
line, branch line 1, and branch line 2. Most of the facilities provided at this station are almost the same as described for the layout shown in Fig. 26.9.
The station at which a railway line or one of its branches terminates is known as a terminal station or a terminal junction (Fig. 26.11). The reception line terminates in a dead end and there is provision for the engine of an incoming train to turn around and move from the front to the rear of the train at such a station. In addition, a terminal station may need to be equipped with facilities for watering, cleaning, coaling, fuelling, and stabling the engines; storing, inspecting, washing and charging the carriages; and such other works.
Fig. 26.11 Terminal station with run round line
On unimportant branch lines, the terminal station will have only one platform, but there are big terminal stations such as the Howrah and Mumbai stations, which are provided with elaborate facilities. The general layout of a big terminal station is shown in Fig. 26.12.
It may be noticed that access from one platform to another is via a concourse and that there are no overbridges provided for this purpose.
Grand Central Station at New York Figure 26.13 depicts the circular loop provided at the Grand Central Station, New York. The provision of circular loops enables the trains to pass through a terminal station without any delay. A further advantage attached to the loop system is that it enables the provision of special stations for dealing with suburban traffic at underground locations away from the congested area of the main terminal and in close proximity to business districts, thus affording direct connections with other stations.