SYSTEMS OF TRACK MAINTENANCE
South Central Railway, after its formation in 1966 by the integration of parts from Southern and Central Railways, inherited a track system that was laid with steel, cast iron and wooden sleepers, maintained manually. Over the last forty one years, a major length f track has been re-laid with modernized track comprising of heavier rails laid on pre-stressed concrete (PSC) sleepers with elastic fastening system, maintained mechanically through track machines. Hence, there are two systems of track maintenance in vogue on S.C.R.
- Manual Maintenance System
- Mechanised Maintenance System
MANUAL MAINTENANCE SYSTEM
Manual maintenance of track is done with conventional sleepers such as steel cast iron and wooden sleepers. SCR has a total of 511 BG running track kilometers of track under manual maintenance.Maintenance Organisation
South Central Railway has six administrative divisions responsible for daily operations including maintenance of assets within their respective jurisdictions. Senior Divisional Engineer – Coordination is the overall in-charge of the civil engineering maintenance organization of the division. He is assisted by Senior Divisional Engineers, Divisional Engineers and Assistant Divisional Engineers, who are assigned specified sections for maintenance. Each Assistant Divisional Engineer is in-charge of a sub-divisional unit and is assisted by 2 to 3 Section Engineers/P.Way, who are equipped with required men and material resources. They are directly responsible for maintenance of track assigned to them.
For the effective inspection and maintenance of track, every 6 to 7 kms. of track is assigned to one permanent way gang, which is headed by a Mate. Each Section Engineer/ P.Way has about 10 to 12 gangs operating under his control. This permanent way gang undertakes maintenance of track by way of packing sleepers, shallow screening; clearing of side drains, attention to level crossing approaches and curves, patrolling of track during monsoon, and such other works that are assigned to them from time to time. Keyman, who is also a part of the permanent way gang is responsible for the proper upkeep of track fittings. Keyman undertakes daily inspection of the railway track within the gang beat, duly tightening any loose fittings apart from looking for any other defects in the track such as rail/weld fractures. Keyman carries out one full round of inspection of his track every day, covering the track on foot.
Maintenance Works
Manual maintenance of track by gangs involves packing of sleepers, shallow screening of ballast, clearing of side drains, attention to track junctions, night patrolling of track during monsoon etc.
Through Packing
Track with conventional sleepers such as wooden, steel and cast iron sleepers are through packed systematically from one end to another by gangs manually in a period of 3 to 4 months, so as to complete the same before monsoon. Any deficiencies in track fittings are made good during through packing operation. Through packing of track helps in ensuring uniform support to the sleepers on the ballast bed and full complement of the track sidings.
Shallow screening
Gangs, as a part of their duty, also undertake shallow screening, i.e. screening of ballast in the shoulders and between sleepers of the track in the required stretches of the track, so as to improve the drainage of track and its maintainability. Gangs complete one round f shallow screening of track in their beat in 3 to 5 years.
Deep Screening of Track
The stone ballast laid in the track below the sleepers gets pulverized gradually due to the passage of traffic and requires deep screening at periodic intervals. Hence, periodical deep screening of track ballast either manually or through machines is done duly screening ballast from between and below the sleepers and on the shoulders and putting back the same in the track. This facilitates improved drainage, better track elasticity and thereby better riding quality. Deep screening of track is done once in 10 years.
MECHANISED MAINTENANCE SYSTEM
As a part of track modernisation, heavier rails and Pre-stressed Concrete (PSC) sleepers have been provided in many sections of SCR. The heavier track structure thus adopted is not amenable for manual maintenance and requires maintenance through track machines. SCR has got 6452 running track kilometres of track laid with PSC sleepers, which is under machine maintenance.
Several track machines as indicated below have been procured and are available with SCR and are being utilised in the maintenance effort.
CSM | Continuous Tamping Machine |
BCM | Ballast Cleaning Machine |
PQRS | Plasser Quick Relaying System (Track laying machine) |
BRM | Ballast Regulating Machine |
T-28 | Points & Crossing Laying Machine |
UNIMAT | Points & Crossing Tamping Machine |
FRM | Shoulder Ballast Cleaning Machine |
DGS | Dynamic Track Stabilizer |
Miscellaneous Works
During monsoon, in certain nominated vulnerable sections, night patrolling of track is done depending on the weather warning messages received from the Meteorological department to look for overflow of water through vulnerable bridges, vulnerable locations, earth slips, land slips etc. As a part of monsoon patrolling, patrolmen cover the track between stations during night time between 1800 hrs. and 0600 hrs. as per the scheduled beat.
CSM – Continuous Tamping Machine
CSM can pack two sleepers at a time in a continuous mode and can pack (tamp) about 1.2 kms of track per hour. SCR has 6 CSM facilitating machine maintenance of pre-stressed concrete track.BCM – Ballast Cleaning Machine
PQRS – Plasser Quick Relaying System
Every year, certain length of identified track, which has completed its useful economic life is renewed with new rails/sleepers. This work of track renewal is done under line block using PQRS portal cranes, which move on temporary auxiliary track laid in advance. The existing track panel of about 12-13 m. length are systematically removed by these cranes and loaded into railway wagons, and new track panels are laid which are also brought in railway flat wagons (BFRs). At the end of the line block, the track is linked up and made safe for passing of trains. PQRS can renew about 170 m. of track per hour of block.BRM – Ballast Regulating Machine
PRC T-28 – Points & Crossing Laying Machine
T-28 machine helps in laying of pre-stressed concrete points and crossings sleepers in track, which are heavy for manual loading. SCR has 2 sets of these machines on its system. Using T-28 machine one PSC turnout can be laid in three hours of line block.
UNIMAT – Points & Crossings Tamping Machine
Pre-stressed concrete sleeper turnouts, being heavy are not amenable for manual packing. Unimat machine with its special maneuverable tamping tools can tamp one complete set of point per hour of working. SCR has 6 Unimat machines working in various divisions.FRM – Shoulder Screening Machine
This machine carries out screening of ballast from the shoulders of track without disturbing the ballast core from below the sleepers. FRM can screen about 600 cum of ballast per hour of working. There are 3 FRM machines working in SCR.DGS – Dynamic Track Stabilizer
This machine helps in quick consolidation of newly deep screened track by imparting vibrations to the track. It is deployed in the rear of BCM machine, which does deep screening of track in advance. DGS helps in accelerating track consolidation and imparting stability to the track, thus helping in early lifting of speed restrictions after deep screening work. There are 5 DGS machines in SCR.CIVIL ENGINEERING DEPARTMENT
Assets At a Glance
Track 7599.593 Track Kms
Buildings 41,66,846 Sq.m. of plinth area
Bridges 117.85 Kms. of water way
Track Details
Among the zonal railways of the Indian Railway System, South Central Railway is the fourth largest in terms of total route kms of track. SCR has 5627.432 route kms of Broad Gauge track and 175.93 route kms of Metre Gauge track.
South Central Railway encompasses nearly the whole of Andhra Pradesh and parts of Karnataka, Maharashtra, Madhya Pradesh and Tamilnadu.
State | Broad-gauge | Meter-gauge | Total |
Andhra Pradesh | 4341.812 | nil | 4341.812 |
Maharashtra | 1010.07 | 105.75 | 1115.82 |
Karnataka | 268.69 | -- | 268.69 |
Madhya Pradesh | -- | 70.18 | 70.18 |
Tamilnadu | 6.86 | -- | 6.86 |
TOTAL | 5627.432 | 175.93 | 5803.36 |
CLASSIFICATION OF ROUTES
According to the norms laid down for classification of routes on Indian Railways, South Central Railway System has the following configuration of route kms:
Broad Gauge System
Classification | Criterion for Classification | Route Kms |
Group 'A' | Track with speed potential up to 160 Kmph | 747.26 |
Group 'B' | Track with speed potential up to 130 Kmph | 3286.785 |
Group 'D' | Sections with sanctioned speed of 110 Kmph | 525.315 |
Group 'D' Spl | Sections with sanctioned speed of 110 Kmph, where the traffic density is very high or likely to grow substantially in the future. | 22.03 |
Group 'E' | Sections and branch lines with present sanctioned speed of less than 100 Kmph | 1046.042 |
Group 'E' Spl | Sections with sanctioned speed of less than 110 Kmph, where the traffic density is very high or likely to grow substantially in the future | -- |
Total | 5627.432 |
Group 'C' Classification is basically for Suburban sections of Mumbai, Delhi, Chennai and Kolkata. As such, there is no section under Group 'C' in South Central Railway.
Metre Gauge System
Classification | Criterion for Classification | Route Kms |
Group 'R3' | Track with speed potential Of 75 Kmph and traffic density between 1.5 – 2.5 GMT | 175.93 |
Total | 175.93 |
Group 'Q' routes are those with maximum speed of more than 75 Kmph and 'R1' routes are those with speed potential of 75 Kmph and traffic density of more than 5 GMT. There are no such routes in SCR.
Group 'R3' route with route of 175.93 kms are slated for conversion to Broad Gauge.
TRACK MODERNISATION
In order to keep pace with the increasing traffic on various routes and also to take care of the heavier axle loads of rolling stock, Track Modernisation had been taken up as a thrust area in South Central Railway. As a part of track modernisation, heavier track structures are provided by way of provision of higher poundage and Ultimate Tensile Strength (UTS) rails on pre-stressed concrete sleepers with elastic fastening devices.
Track Modernisation mainly involved the following areas:
- Use of heavier poundage rails
- Provision of Pre-stressed Concrete (PSC) sleepers
- Provision of increased clean ballast cushion
- Provision of PSC sleepers in track junctions
- Welding of rails to form long continuously welded rails of 3 kms or more in length
Use of Heavier Poundage Rails
Prior to track Modernisation, rails with weight of 90 lbs. Per metre and 75 lbs. Per metre with Ultimate Tensile Strength (UTS) of 72 Kg/mm were in use. In order to facilitate higher speeds and haulage of heavier wagons, heavier rails of 60 Kg/m and 52 Kg/m weight with UTS of 90 Kg/mm are being used while replacing existing rails. SCR has already got 6435.825 km of track replaced with these 52/60 kg/m rails of 90 UTS.
Provision of Pre-stressed Concrete (PSC) Sleepers
In SCR, as part of track Modernisation, out of a total BG running track kilometres of 7599.593 kms, 7375.555 Kms. of track has already been provided with pre-stressed concrete sleepers.
Provision of Increased Clean Ballast Cushion
Stone ballast provided in the track affords resilience and stability to the track, resulting in improved ride quality. As a part of modernisation, the ballast cushion below the bottom of sleepers have been increased from about 150 mm, existing earlier, to about 300 to 350 mm, after laying of PSC sleepers.
Provision of PSC Sleepers in Track Junctions
Track junctions (turnouts), which are provided in station yards were earlier provided with wooden sleepers and steel sleepers. In view of the higher traffic density and also to conserve precious forest resources, SCR has gone in for provision of pre-stressed concrete sleepers for turnouts in station yards as a priority area in track Modernisation. So far, 4482 points and crossings on BG running track have been renewed with pre-stressed concrete sleepers. Every year about 300 turnouts with PSC sleepers are being provided in the place of existing wooden/steel sleepers.
Welding of Rail Joints
Individual rails rolled in India are of 13/26 metre length. Rails, when laid in track can be joined either by provision of fish plates or by welding the rail joints. Fishplated joints in track contribute to heavy noise and bad running as wheel has to jump across the gap at the joint. Hence welding of rails is done to convert the rails panels into long or continuous welded rail panels of a few kilometres length. These panels are called Long Welded Rails (LWRs) or Continuous Welded Rails (CWRs).
Welding of rails for conversion into LWRs/CWRs is another priority area in Track Modernization as this will facilitate smoother riding and also reduce the maintenance effort. Out of total BG running track kilometers of 7599.593 in SCR, the track in a length of 6667 Kms has so far been converted into LWR/CWR.
Welding in SCR is done by two methods:
- Flash Butt Welding
- Alumino-Thermic (AT) Welding
Flash Butt Welding
The individual rails of 13/26 m. length received from steel rolling plants are initially sent to Flash Butt Welding Plant at Moula_Ali, Secunderabad. The individual rails are then welded into rail panels of 10-rail length by flash butt welding technique.Flash butt welding technique involves pre-heating of rail ends by passing high ampere low voltage current and then the rail ends are cyclically brought closer and separated, which results in heavy sparking between the rail ends. After the rail ends are brought to a molten state, butting of rail ends is done under pressure.
Flash butt joints have very high fatigue strength and are preferred to other types of welds. The rail panels of 10-rail length and 20-rail length formed by flash butt welding are transported from the Flash Butt Welding Plant to the field locations by loading into specially designed railway flat wagons. These panels are unloaded at the site through specially designed end unloading chutes fitted to the rearmost wagon.
Alumino Thermic (AT) Welding
AT Welding is basically a field technique, wherein the joints in the 10-rail panels are welded in the track to convert into LWR/CWR. In AT Welding, specially fabricated dry clay moulds are fitted to the rail ends to be welded, duly creating a gap of 25 mm between the rails. The gap is filled by pouring hot molten metal into the mould of the same metallurgical composition, as that of the parent rail material.
Testing of Rails/Welds by USFD
Monitoring and maintaining the integrity of rail/Weld sections during their service life is paramount for ensuring safety of track and increasing asset life. The rails and welds in track are periodically tested by Ultra Sonic Flaw Detection (USFD) technique to detect any incipient minor flaws caused due to the passage of traffic and prompt remedial action taken in case of detection of any flaws.
TRACK MONITERING
Due to the passage of continuous traffic, track parameters slowly get altered and a few bad running locations get formed at isolated locations. Monitoring of the track in terms of track parametres and riding quality is done on a continuous basis by the following means:
- Inspections by Maintenance Organisation
- Objective measurement of track parameters by Track Recording Cars (TRCs)
- Determination of riding quality using Oscillation Monitoring System (OMS)
Inspections by Maintenance Organisation
Inspections in the locomotives of fast express/mail trains are done by maintenance Engineers periodically to identify locations of bad running which are promptly attended to. The Maintenance Engineers do physical inspection of track at periodical intervals by travelling along the track in trolleys, either motor powered or pushed manually. During these trolley inspections, the defects, if any, in the track are physically measured and prompt remedial action is taken.
Measurement of Track Parametres by Track Recording Cars (TRCs)
To make an objective assessment of the track parametres of the entire length of track, special Track recording cars, which carry special equipment to measure the track parameters on a continuous basis are run on various sections of the Railway at periodical intervals. Based on the assessment of the track parametres, prompt attention is given to the needy locations.
Determination of Riding Quality by Oscillation Monitoring System (OMS)