Track Monitoring & Tolerances PDF

CHAPTER – 5 TRACK MONITORING & TOLERANCES ********************* PART – ‘A’ - TRACK MONITORING 501 General - Inspections by individuals on foot or by trolley, locomo...

CHAPTER – 5 TRACK MONITORING & TOLERANCES ********************* PART – ‘A’ - TRACK MONITORING 501 General - Inspections by individuals on foot or by trolley, locomotive, and rear vehicle enable the Permanent Way staff to carry out assessment of the quality of track based on their expertise and experience. For objective assessment of track quality, the following mechanized means are being used on Indian Railways. (1) Track Recording Car (2) Oscillation Monitoring System (3) Oscillograph Car 502 Track Recording Cars: - These enable collection of discrete values of various track geometry Parameters on selected sampling interval under loaded condition. The TRCs work on inertial principle of measurements for various track geometry Parameters except Gauge. (1) Inertial principle of measurements:- TRC measures lateral and vertical accelerations with the help of accelerometers placed at coach floor / bogie frame. The acceleration values obtained are integrated twice to get loci of the location of accelerometers. The relative displacements between rail and accelerometer locations are obtained from displacement transducers (LVDT)/LASER based contactless sensors. The loci of accelerometers are combined with relative displacement between accelerometers and rail obtained from sensors to derive the vertical and lateral profile of the rail. These measurements are further corrected for roll and yaw motion of coach using gyroscopes. (2) Gauge Measurement:- For measurement of Gauge Parameter, the following types of Gauge sensors are in use on Indian Railways: (a) Contact gauge sensor (used up to maximum recording speed of 100 Kmph); and (b) Contactless laser based gauge sensor (used up to maximum recording speed of 160 Kmph); 503 Quick Calibration, Recording and Speed:- (1) Before start of any run (day light hours only), it should be ensured that quick calibration of the system has been done satisfactorily. (2) The track recording car specials must have a through run over the section between two major stations and run through main lines only at all stations. (3) The track parameter recording is independent of speed above a minimum speed of 20 Kmph (needed for inertial platform); however, the Track Recording Cars should be run at the maximum speed of Section/TRC for objective assessment of ride quality in terms of acceleration peaks and Ride Index. Any recording done below speed of 20 Kmph is taken as "Non-recorded". 504 Arrangements for Running Track Recording Car:- (1) On receipt of monthly program for running of TRCs on various zonal railways issued by RDSO, Zonal Railways shall arrange for suitable power, crew, consumables and path for an uninterrupted run of the Track Recording Car as per RDSO program. Page 201 of 417 (2) ADENs & SSEs headquartered at originating / halting stations shall coordinate for proper placement, watering, charging, and other assistance for the TRC special. 505 Officials to accompany the TRC run:- Sectional Sr. DEN/DEN, ADEN and SSE/P.Way (In-charge) shall accompany TRC run in their sections. Sectional Sr. DEN/DEN shall ensure proper liaison in the control office for suitable path and monitoring of the TRC special. The soft copy of TRC recording shall be provided by RDSO officials and the same shall be uploaded in TMS. 506 Frequency of Track Recording:- The frequency of Track geometry monitoring by TRC is as under: Sl. No. Speed Slab Frequency i) Routes with speeds above 130 Kmph Once in 2 months Routes with speeds above 110 Kmph and up to 130 ii) Once in 3 months Kmph Routes with speeds above 100 Kmph and up to 110 iii) Once in 4 months Kmph iv) Routes with speeds up to 100 Kmph Once in 6 months 507 Track Geometry Parameters Recorded by TRC: - The following track geometry parameters are measured by the Track Recording Cars: (1) Unevenness of left & right rail (on two selected chords) (2) Alignment of left & right rail (on two selected chords) (3) Twist (calculated on two selected bases) (4) Variation of gauge over nominal gauge, which is 1676 mm for IR. (5) Vertical and lateral accelerations on coach floor above bogie pivot, in test vehicles (Locomotive) (6) Curve details (only in contactless laser based TRCs) (7) Speed of recording 508 Chords for Measurements/Report:- Both types of TRCs have the ability to measure and calculate track geometry parameters on two user selectable chords/bases in the range of 2 to 20 metres. The shorter one is termed as short chord/base and the other one as long chord/base (denoted by suffix 1 & 2 respectively). The length of short and long chord/base for track monitoring are as under: SN Parameter Short Chord / Base (m) Long Chord/ Base (m) 1 Unevenness 9.0 (UN-1) 18.0 (UN-2) 2 Alignment 9.0 (AL-1) 15.0 (AL-2) 3 Twist 3.0 (TW-1) 15.0 (TW-2) 509 Reporting of TRC Results:- While recording the track parameters, on-line reports are generated by TRC for each block of 200 metre and for the entire kilometre: (1) Details of every block of 200 m:- (a) Standard Deviation values of Unevenness of left & right rail on short and long chord (b) Standard Deviation value of Alignment of left & right rail on short and long chord (c) Average of Variation of gauge over nominal gauge (1676 mm) Page 202 of 417  (d) Maintenance Instructions corresponding to Gauge (MI-G) based on Need Based Maintenance Limit (NBML) and Urgent Maintenance Limit (UML) values for average/mean gauge (e) Average speed (f) Vertical and Lateral Ride Index on coach floor above bogie pivot (accelerometer location) and in test vehicle (Locomotive) in Laser Contact less TRCs (g) Parameter Index for Unevenness (UNI-1 & UNI-2) and Alignment (ALI-1 & ALI-2) on short and long chords. (h) Track Quality Index (TQI) on both short and long chord i.e., TQI-S and TQI-L (i) Composite Track Quality Index for Sections having Speed > 100 Kmph (TQI-C) (j) Maintenance Instructions corresponding to SD (MI-SD) based on PML and NBML for Unevenness and Alignment (2) Results reported for whole kilometre: (a) Total number of peaks above Need Based Maintenance Limits (NBML) on long chord and short chord for Alignment and Unevenness. (b) Total number of peaks above Need Based Maintenance Limits (NBML) and Urgent Maintenance Limit (UML) on short base for Twist. (c) Total number of peaks above Need Based Maintenance Limits (NBML) and Urgent Maintenance Limit (UML) for Gauge. (d) Total number of peaks above Urgent Maintenance Limit (UML) for vertical and lateral acceleration. (e) Parameter Indices for Unevenness (UNI-1 & UNI-2) and Alignment (ALI-1 & ALI- 2) on short and long chord. (f) Track Quality Index (TQI) on both short and long chord i.e. TQI-S and TQI-L. (g) Composite Track Quality Index for sections having speed > 100 Kmph (TQI-C). (h) Average speed. (i) Vertical and Lateral Ride Index on coach floor above bogie pivot (at accelerometer location). (j) 10 highest peak values of alignment and unevenness Parameters with location on long and short chord out of the maximum peak values measured for each 50 m block of a kilometer. (k) 10 highest peak values of Twist Parameter with location on short base out of the maximum peak values measured for each 50 m block of a kilometer. (l)10 highest peak values of variation of gauge (over nominal gauge of 1676 mm) parameter with location out of the maximum peak values measured for each 50 m block of a kilometer. (m) 10 highest peak values of vertical and lateral accelerations with location out of the maximum peak values measured for each 50 m block of a kilometer. (n) 10 maximum peak values of Twist on short base exceeding Urgent Maintenance Limits (UML) with location. (o) 10 maximum peak values of Gauge (over nominal gauge of 1676 mm) exceeding Urgent Maintenance Limits (UML) with location. (p) 10 maximum peak values of vertical and lateral accelerations exceeding Urgent Maintenance Limits (UML) with location. (3) SMS alerts would be generated for cases of exceedances of UML during TRC recordings. These alerts would be sent through TMS to concern JE/P.Way, SSE/P.Way, ADEN and sectional DEN/Sr.DEN along with Sr.DEN/Coordination. Page 203 of 417 510 Action to be Taken After Track Recording by TRC:- (1) Spots/blocks requiring attention as per Parameter limits, and acceleration peak limits set as UML should be noted by the ADEN and SSE/P.Way accompanying the car for giving requisite action/attentions as per Para 521. (2) Track recording results should be uploaded in TMS by SSE/In-charge of TRC after end of days recording and analyzed in the Divisional Office. (a) A comparison of the records of each section shall be made with the previous run. (b) Analysis shall be done for identifying the blocks/locations needing Planned, Need Based and Urgent attention for onward transmission to concerned maintenance units. (c) Analysis of data to generate various reports/charts using TRC offline software or through TMS to take up the maintenance and precautionary action as detailed in Para 523. Alerts with respect to UML will also be generated by TMS after uploading of data in TMS. (d) Maintenance units shall take action for maintenance as detailed in Para 523. 511 Parameter Indices:- For characterization of the Track Quality, the Parameter wise Indices viz. unevenness index (UNI-1 and UNI-2) and Alignment Index (ALI-1 and ALI-2) on short and long chord for each block of 200 m are computed as under: (1) Alignment Index: (a) On Short Chord (ALI1): ((𝑆𝐷 −(𝑆𝐷𝑁𝑇𝐿−𝐴𝐿−1)) −[((1.3×𝑆𝐷𝑀−𝐴𝐴𝐿−1 ] 𝐴𝐿𝐼1 = 100 × 𝑒 𝑁𝐵𝑀𝐿−𝐴𝐿−1−(𝑆𝐷𝑁𝑇𝐿−𝐴𝐿−1)) (b) On Long Chord (ALI2): ((𝑆𝐷 −(𝑆𝐷𝑁𝑇𝐿−𝐴𝐿−2)) −[((1.3×𝑆𝐷𝑀−𝐴𝐴𝐿−2 ] 𝐴𝐿𝐼2 = 100 × 𝑒 𝑁𝐵𝑀𝐿−𝐴𝐿−2−(𝑆𝐷𝑁𝑇𝐿−𝐴𝐿−2)) (2) Unevenness Index: (a) On Short Chord (UNI1): ((𝑆𝐷 −(𝑆𝐷𝑁𝑇𝐿−𝑈𝑁−1)) −[((1.3×𝑆𝐷𝑀−𝐴𝑈𝑁−1 ] 𝑈𝑁𝐼1 = 100 × 𝑒 𝑁𝐵𝑀𝐿−𝑈𝑁−1−(𝑆𝐷𝑁𝑇𝐿−𝑈𝑁−1)) (b) On Long Chord (UNI2): ((𝑆𝐷 −(𝑆𝐷𝑁𝑇𝐿−𝑈𝑁−2)) −[((1.3×𝑆𝐷𝑀−𝐴𝑈𝑁−2 ] 𝑈𝑁𝐼2 = 100 × 𝑒 𝑁𝐵𝑀𝐿−𝑈𝑁−2−(𝑆𝐷𝑁𝑇𝐿−𝑈𝑁−2)) Where, ALI1 Alignment Index on short chord i.e. on 9.0 metre chord ALI2 Alignment Index on long chord i.e. on 15.0 metre chord UNI1 Unevenness Index on short chord i.e. on 9.0 metre chord UNI2 Unevenness Index on long chord i.e. on 18.0 metre chord SDM-AAL-1 Average of measured SD value of alignment of left and right rail on short chord SDNTL-AL-1 SD value of New Track Limit of alignment on short chord SDNBML-AL-1 SD value of Need Based Maintenance Limit of alignment on short chord SDM-AAL-2 Average of measured SD value of alignment of left and right rail on long chord SDNTL-AL-2 SD value of New Track Limit of alignment on long chord SDNBML-AL-2 SD Value of Need Based Maintenance Limit of alignment on long chord SDM-AUN-1 Average of measured SD value of unevenness of left and right rail on short chord SDNTL-UN-1 SD value of New Track Limit of unevenness of short chord SDNBML-UN-1 SD value of Need Based Maintenance limit of unevenness on short chord SDM-AUN-1 Average of measured SD value of alignment of left and right rail on short chord SDNTL-UN-2 SD value of New Track Limit of unevenness on long chord SDNBML-UN-2 SD value of Need Based Maintenance Limit of unevenness on long chord Page 204 of 417 512 Track Quality Index (TQI):- (1) TQI is prescribed for overall assessment of track quality for IR routes categorized in four different speed bands. The TQI could be worked out by expressions given in (a) and (b) below using indices for short chord (for all speeds) as well as long chord (for speeds more than 100 Kmph) respectively. Additionally, a composite TQI can also be calculated by expressions given in (c) below. (a) On Short Chord 𝑈𝑁𝐼1 + 𝐴𝐿𝐼1 𝑇𝑄𝐼𝑆 = ( ) 2 (b) On Long Chord (For Speed >100 Kmph only) 𝑈𝑁𝐼2 + 𝐴𝐿𝐼2 𝑇𝑄𝐼𝐿 = ( ) 2 (c) Composite Track Quality Index (For Speed >100 Kmph only) 𝑈𝑁𝐼1 + 𝐴𝐿𝐼1 + 𝑈𝑁𝐼2 + 𝐴𝐿𝐼2 𝑇𝑄𝐼𝐶 = ( ) 4 (2) The TQI values based on the above expressions are only an indicator; the actual maintenance of track shall be planned on the basis of SD values and peak values of different track parameters in comparison to respective benchmark values. 513 Oscillation Monitoring System:- This equipment measures the track performance by measurement of vehicles response in terms of vertical and lateral accelerations. The real time output of the equipment is in the form of value of peaks exceeding the limiting value, their locations, and Ride index. These values are available for both vertical and lateral accelerations. (1) The OMS equipment used for oscillation monitoring uses a portable accelerometer and transducers converting the oscillations into electrical signals, which can be recorded electronically and processed. The OMS equipment used should preferably be GPS enabled. (2) (i) The OMS equipment shall be kept in the rearmost coach of the fastest train in the section or in a dedicated coach, which shall be attached, as last vehicle, to the fastest train in the section. (ii) The OMS equipment shall be kept on the coach floor (as close to the bogie pivot as possible) on the free end of the coach. (3) The stored data should be uploaded in TMS for analysis and maintenance planning. 514 Frequency of OMS Recording:- (1) On routes having speed above 100 Kmph – Once every month (2) Others routes – Once in two months 515 Recording of Defects:- To assess the track quality, vertical and lateral acceleration peaks exceeding the values as below are to be considered. (1) On routes having speed above 110 Kmph (on A & B routes) – Greater than 0.15 g. (2) Others routes having speed up to 110 Kmph – Greater than 0.2 g. Page 205 of 417 516 Classification of Track Quality:- For judging the track quality, the following criteria could be used (average total number of peaks per km) to classify a continuous section for track quality (SSE/P Way’s jurisdiction/Subdivision/division): Track Quality Very Good Good Average Section Speed Speed Above 110 Kmph Less than 1.0 1-2 Greater than 2 Others Less than 1.5 1.5-3.0 Greater than 3 517 Oscillograph Car:- (1) Brief Description of the Car – The Oscillograph cars monitor riding quality of track at Maximum Sanctioned Speed of the section with the help of an accelerometer that digitally records the accelerations. The vertical and lateral accelerations at the vehicle floor level are recorded by keeping the accelerometer as close to the bogie pivots as possible. (2) Frequency of Recording – The frequency of recording shall be as under: (a) On routes having speed above 110 Kmph and up to 130 Kmph – Once in 6 months (b) On routes having speed above 130 Kmph and up to 160 Kmph – Once in 4 months (3) Analysis of Oscillograph Car results – Vertical and lateral accelerations above the threshold values, mentioned hereunder, are separately counted. (a) Loco Cab floor: In vertical mode - 0.20 g for all locos (Diesel and Electric) In Lateral mode - 0.20 g for diesel and electric locos (with double stage suspension) In Lateral & Vertical mode- 0.30 g (for Locos with single stage suspension) (b) Passenger Coach Floor: In vertical and lateral modes - 0.15 g. (4) Reports and Interpretation of Results – The km wise analysis and results are given in Annexure - 5/1 under the following heads (In addition the Speed grouping table) on the basis of the number of peaks counted above threshold values for a particular locomotive: (a) Station Yards (b) Other than Station Yards (Isolated locations) (c) Active continuous stretches 518 Use of Oscillograph Car Recordings:- (1) Threshold values of acceleration are given in Para 517 (3). The track should be attended to at all such locations where peaks above threshold values are reported so as to ensure good riding. (2) Efforts should be made not only to check the extent of defect but also to find out whether it is occurring in an active patch (defined as per Statement A, B and C of Oscillograph Results)as it may lead to excessive oscillations. Page 206 of 417  PART – ‘B’ TRACK TOLERANCES 519 General - The track deteriorates structurally and geometrical Parameters de-grade with the passage of traffic resulting in decline in ride quality. The rate of deterioration of the track depends on the quality of track at that point in time. Various limits for track geometrical Parameters are laid down to assess the ride quality of track and to plan necessary maintenance interventions during the service life. 520 New Track Tolerances:- (Back to Para 716) (1) Utmost care should be taken during linking of track to ensure good quality of work. As a good practice, the laying standards of track geometry for track laid with new Material are as under: (To be measured three months after speed is raised to normal). (2) For measurements recorded by TRC. (a) SD Values for Unevenness and Alignment: Sl. Speed upto 100 Speed above 100 Kmph; and Parameter No. Kmph up to 160 Kmph 1. UN-1 2.0 mm 1.4 mm 2. UN-2 - 1.9 mm 3. AL-1 1.4 mm 1.1 mm 4. AL-2 - 1.3 mm (b) Peak Values for Unevenness and Alignment: Sl. Speed upto Speed above 100 Kmph; and Parameter No. 100 Kmph upto 160 Kmph 1. UN-1 6.0 mm 4.0 mm 2. UN-2 - 6.0 mm 3. AL-1 4.0 mm 3.0 mm 4. AL-2 - 4.0 mm (3) For measurements recorded in floating conditions: (Back to Para 429, 715, 716) (a) Gauge: For new track and through renewal of track, following tolerances would be applicable- (i) For straight including curves of radius up to 350 m and more -5 mm to +3 mm (ii) For curves of radius less than 350 m Up to +10 mm (b) Other parameters: S. Parameter Description of Measurement Value No 1 Gauge Sleeper to sleeper variation 2 mm Expansion Over average gap worked out by recording 20 2 ± 2 mm gap successive gaps Low joints not permitted High joints not more than + 2 mm 3 Joints Squareness of joints on straight ±10 mm Spacing of 4 With respect to theoretical spacing ± 20 mm sleepers 5 Cross level To be recorded on every 4th sleeper ± 3 mm 6 On straight on 10 m Chord ± 2 mm Variation over theoretical versines: (On 20 m Chord). 7 Alignment On curves of Radius more than 600 m 5 mm Variation over theoretical versines: (On 20 m Chord). 8 On curves of Radius less than 600 m 10 mm Longitudinal Variation with reference to approved longitudinal 9 50 mm level sections. Page 207 of 417  521 Planning of Maintenance – (Back to Para 510) For planning/taking up maintenance of track in respect of Alignment, Unevenness, Gauge and Twist Parameters based on TRC results, track shall be categorized under following three categories: (1) Track requiring planned maintenance (2) Track requiring need based maintenance (3) Track requiring urgent maintenance (a) Planned Maintenance Limit (PML) – (i) These tolerances provide a guidance to plan through maintenance of track in a complete block section. These Limits, if exceeded, require that track geometry condition be analysed and considered for planned maintenance operations. (ii) The Planned Maintenance Limits (PML) for Unevenness and Alignment are based on Standard Deviation (SD) values, as these Parameters affect Ride quality. (iii) Peak based limits are not stipulated for unevenness and alignment for planned maintenance as the planned maintenance is to be carried out by track machines for which the planning will be based on standard deviation values only. (b) Need Based Maintenance Limit (NBML) – (i) These limits are defined for applying timely correction before the defects size grows to the level of Urgent Maintenance Limit (UML); requiring traffic slow down. Allowable time for attention to defects exceeding the NBML would depend upon the magnitude of the defects and various factors affecting track geometry deterioration such as sectional speed, axle load, traffic volume etc. (ii) The Need Based Maintenance Limits (NBML) are based on Standard Deviation and peak values for Unevenness and Alignment. For Gauge and Twist, these limits are based on peak values. (c) Urgent Maintenance Limits (UML) – (i) These limits are so specified that upon their exceedances, the permitted speed should be reduced; which can be restored only after attending the track. (ii) These are laid in terms of acceleration limits on comfort consideration and peak values for Gauge and Twist. 522 Maintenance Limits for Different Speed Bands: Based on TRC and OMS results, various limits of PML NBML and UML for Unevenness, Alignment, Gauge and Twist Parameters for different speed bands are stipulated as under: (1) For Speeds up to 100 Kmph: Planned Need Based Urgent SN Parameter Maintenance Maintenance Limit Maintenance Limit (PML) (NBML) Limit (UML) 1 Unevenness SD-6.8 mm 1.1 UN-1 SD-5.0 mm Peak-20 mm Vertical and 1.2 UN-2 - - lateral 2 Alignment acceleration SD-4.9 mm peak of 0.30 g 2.1 AL-1 SD-3.3 mm Peak -15 mm 2.2 AL-2 - - 3 Gauge Page 208 of 417 3.1 Mean gauge over 200 m section over nominal gauge -10 mm to + 12 (a) Straight - -8 mm to +10 mm mm -7 mm to +17 (b) Curve with radius 440 m or more - -5 mm to +14 mm mm Curve with radius less than 440 m -7 mm to +20 (c) (Permissible speed as per relevant - -5 mm to +18 mm mm Para of IRPWM) 3.2 Isolated defects – Nominal track gauge to peak value -12 mm to + 15 (a) Straight - -10 mm to +12 mm mm -11 mm to +20 (b) Curve with radius 440 m or more - -7 mm to +17 mm mm Curve with radius less than 440 m -8 mm to +25 (c) (Permissible speed as per relevant - -6 mm to +22 mm mm Para of IRPWM) 4 Twist (TW-1) 5 mm/m 7 mm/m Note: In case of curve, the limits for alignment prescribed are above average versine. (2) For Speeds above 100 Kmph and up to 110 Kmph: Planned Need Based Urgent Maintenance SN Parameter Maintenance Maintenance Limit Limit (UML) Limit (PML) (NBML) 1 Unevenness SD-5.5 mm 1.1 UN-1 SD-3.8 mm Peak-17 mm SD-7.5 mm 1.2 UN-2 SD-5.4 mm Vertical and lateral Peak-23 mm acceleration peak of 0.30 2 Alignment g SD-3.9 mm 2.1 AL-1 SD-2.5 mm Peak -12 mm SD-6.7 mm 2.2 AL-2 SD-4.1 mm Peak-20 mm 3 Gauge 3.1 Mean gauge over 200 m section over nominal gauge (a) Straight - -8 mm to +10 mm -10 mm to + 12 mm Curve with radius 440 (b) - -5 mm to +14 mm -7 mm to +17 mm m or more Curve with radius less than 440 m (c) (Permissible speed - -5 mm to +18 mm -7 mm to +20 mm as per relevant Para of IRPWM) 3.2 Isolated defects – Nominal track gauge to peak value (a) Straight - -10 mm to +12 mm -12 mm to + 15 mm Curve with radius 440 (b) - -7 mm to +17 mm -11 mm to +20 mm m or more Curve with radius less than 440 m (c) (Permissible speed - -6 mm to +22 mm -8 mm to +25 mm as per relevant Para of IRPWM) 4 Twist (TW-1) 4 mm/m 7 mm/m Note: In case of curve, the limits for alignment prescribed are above average versine. Page 209 of 417 (3) For Speeds above 110 Kmph and up to 130 Kmph: Planned Need Based Urgent SN Parameter Maintenance Maintenance Limit Maintenance Limit Limit (PML) (NBML) (UML) 1 Unevenness SD-4.9 mm 1.1 UN-1 SD-3.3 mm Peak-15 mm SD-7.4 mm 1.2 UN-2 SD-5.1 mm Vertical and lateral Peak-22 mm acceleration peak of 2 Alignment 0.25 g SD-3.6 mm 2.1 AL-1 SD-2.5 mm Peak -11 mm SD-5.3 mm 2.2 AL-2 SD-3.5 mm Peak-16 mm 3 Gauge 3.1 Mean gauge over 200 m section over nominal gauge (a) Straight - -8 mm to +10 mm -10 mm to + 12 mm Curve with radius 440 m or (b) - -5 mm to +14 mm -7 mm to +17 mm more Curve with radius less than 440 m (Permissible speed (c) - -5 mm to +18 mm -7 mm to +20 mm as per relevant Para of IRPWM) 3.2 Isolated defects – Nominal track gauge to peak value (a) Straight - -10 mm to +12 mm -12 mm to + 15 mm Curve with radius 440 m or (b) - -7 mm to +17 mm -11 mm to +20 mm more Curve with radius less than 440 m (Permissible speed (c) - -6 mm to +22 mm -8 mm to +25 mm as per relevant Para of IRPWM) 4 Twist (TW-1) 4 mm/m 6 mm/m Note: In case of curve, the limits for alignment prescribed are above average versine. (4) For Speeds above 130 Kmph and up to 160 Kmph: Planned Need Based Urgent Maintenance Limit SN Parameter Maintenance Maintenance (UML) Limit (PML) Limit (NBML) Vertical and lateral 1 Unevenness acceleration peak of 0.20 g SD-4.4 mm 1.1 UN-1 SD-2.9 mm Peak-13 mm SD-6.6 mm 1.2 UN-2 SD-4.4 mm Peak-20 mm 2 Alignment SD-3.6 mm 2.1 AL-1 SD-1.9 mm Peak -11 mm SD-4.9 mm 2.2 AL-2 SD-2.5 mm Peak-15 mm 3 Gauge 3.1 Mean gauge over 200 m section over nominal gauge -6 mm to +10 (a) Straight - -8 mm to + 12 mm mm Curve with radius 440 m or -5 mm to +13 (b) - -7 mm to +15 mm more mm Curve with radius less than 440 -5 mm to +18 (c) m (Permissible speed as per - -7 mm to +20 mm mm relevant Para of IRPWM) Page 210 of 417 3.2 Isolated defects – Nominal track gauge to peak value -8 mm to +12 (a) Straight - -10 mm to + 15 mm mm Curve with radius 440 m or -6 mm to +16 (b) - -9 mm to +20 mm more mm Curve with radius less than 440 -6 mm to +22 (c) m (Permissible speed as per - -8 mm to +25 mm mm relevant Para of IRPWM) 4 Twist (TW-1) 3.5 mm/m 5 mm/m Note: In case of curve, the limits for alignment prescribed are above average versine. 523 Action to be Taken Based on TRC Results: (Back to Para 510, 602, 604) (1) Action to be taken on exceedance of UML: Spots/blocks exceeding track Parameter limits, and acceleration peak limits set as UML should be noted by the ADEN and SSE accompanying the TRC and suitable speed restrictions have to be immediately imposed, which shall be relaxed only after suitable attention/maintenance of track at concerned location. Similar action should be taken on exceedance of UML during OMS run also. (2) Action to be taken on exceedance of NBML: (i) The blocks requiring Need Based Maintenance on the basis of laid down SD based NBML and isolated spots on the basis of laid down Peak based NBML shall be identified using offline software or through TMS. All such blocks and isolated spots should be attended within a reasonable time of TRC run so that good ride quality is maintained and the track geometry does not exceed the UML. The reasonable time would be different for different sections depending upon the magnitude of defects, cause of the defect, traffic density of the section, maximum permissible speed of the section etc. The officials responsible for maintenance at various levels have to plan the deployment of maintenance resources keeping in view the relative priority and availability of maintenance resources. (ii) Gap between two successive NBML locations in block sections/yards should also be tamped while attending these NBML locations if this gap is less than/equal to 200 m. (1 TRC block). (iii) While attending an NBML block in the yard in which any portion of the turnout falls, the entire turnout should be tamped. (3) Planning of through tamping based on PML: (i) The blocks requiring planned maintenance on the basis of laid down SD based PML shall be identified for block sections and for yards separately using off line software or through TMS. The block section for any main line should be treated from block (TRC block of 200 m) of last SEJ of preceding station to block of first SEJ of current station. Both the blocks containing above SEJ would be excluded from the block section on any particular line (UP & DOWN separately). Similarly, the yard would be treated from a block of 200 m containing 1st SEJ to block of last SEJ on any particular line (UP & DOWN separately) of the concerned station/yard. In case of CWR through yards, the yard should be taken as 50 metres beyond farthest SRJ/ Back of crossing of turnout from centre of station yard on either side on any particular line (UP and DN separately). Page 211 of 417  (ii) The block section should be planned for through tamping if the percentage of blocks exceeding PML is more than 40%. (iii) Yards should be planned for through tamping if the percentage of blocks exceeding PML is more than 50%. Tamping of turnouts and straight of all other passenger loop lines should be planned on condition basis by ADEN while machines are deployed in yard for need based or planned attention of main line of yards. (4) Maintenance action when track recording is not done (i) For sections in which TRC has not run for more than one year and the last tamping has been done more than two years before, the need based maintenance and urgent maintenance should continue to be carried out based on OMS recording and other inspections. (ii) Sectional Sr.DEN/DEN should periodically (at suitable intervals not greater than six months) review the need for maintenance of track of each such block sections / yards based on OMS recording , other inspections and other maintenance considerations. (iii) Through tamping of such block sections / yards, if considered necessary based on OMS recording and other considerations, should be proposed for inclusion in planning of Through Tamping by Sr.DEN / DEN of section through Sr.DEN / Coordination of Division for approval of CTE. 524 Realignment Criteria for Curves:- (Back to Para 418) The running over a curve depends not only on the difference between the actual versine and the designed versine but also on the station to station variation of the actual versine values, which determine the rate of change of lateral acceleration, on which depends the riding comfort. Sl. No. Speed on curve Limits of Station to Station Variation of Versine (mm) 10 mm 160 Kmph and up 1 (15 mm for speed of 110 Kmph); or to 110 Kmph 20% of average Versine on circular portion, whichever is more. Below 110 Kmph 20 mm; or 2 and up to 50 Kmph 20% of average Versine on circular portion, whichever is more. 40 mm; or 3 Below 50 Kmph 20% of average Versine on circular portion, whichever is more. In case exceedances of the above Limit is observed during inspection, local adjustment may be resorted to in cases where the variation of versine between adjacent stations is only at a few locations, at the earliest possible. If more than 20% stations are having versine variations above the limits prescribed, complete realignment of curve should be planned within a month. 525 Track Parameters in Floating Conditions:- (Back to Para 429, Ann. 6/9) The Gauge and Twist values for manual measurement in floating conditions are as under: (1) Gauge: While it is desirable to maintain correct gauge, variation in gauge may be there due to age and condition of the rail, sleepers, and fastenings. The limits of gauge as per measurement in floating condition, for the guidance of the engineering officials regarding condition of track from passenger comfort perspective shall be as given below, provided that generally a uniform gauge can be maintained over long lengths. Page 212 of 417  a) On straight Track -6 mm to +6 mm b) On curves with radius 440 m or more -6 mm to +15 mm c) On curves with radius less than 440 m Up to + 20 mm In case of exceedances of these limits, the results of last TRC/OMS shall be analyzed for planning suitable maintenance action. (2) Twist: It is desirable to maintain the track geometry for a comfortable ride at sectional speed. The limits of twists as per measurement in floating condition, for guidance of the engineering officials regarding condition of track from passenger comfort perspective shall be as under; (to be calculated on a base of 3.0 m) (i) On straight and curve track, other than transition - 3.5 mm/m (ii) On transition of curve- 2.1 mm/m (Local defects above Designed value) In case of exceedances of above limits, the results of last TRC/OMS shall be analyzed for planning suitable maintenance action. 526 Track Parameters for Low Speeds:- For guidance of field officials, following track Parameters are stipulated in floating conditions, for maintenance of tracks where speeds are low such as worksite, yard line, etc. Peak value of UN Peak value of twist Speed Permissible gauge (on 3.6 m chord) (on 3.0 m chord) (in Kmph) range in mm in mm Up to 45 22 18 -10 to +27 mm Up to 30 24 21 -10 to +27 mm Up to 15 33 25 -12 to +27 mm 527 Stability of Trains Against Derailment: The stability of trains against derailment depends upon several factors such as track geometry, vehicle characteristics and state of their maintenance and speed of the particular vehicle at relevant point of time etc. Rail wheel interaction is, thus, a complex phenomenon and, therefore, safety tolerance for track alone cannot be prescribed in Isolation. Accordingly, safety tolerances for maintenance of track have not been prescribed on Indian Railways. Each derailment case, therefore, needs careful examination of all available evidence, in respect of track, rolling stock, speed and other factors considered relevant, to arrive at the cause. The provisions and tolerances mentioned herein before and elsewhere in this Manual are with a view to maintain track geometry for good riding comfort considered and deviation from these maintenance Parameters should not be considered alone for cause of accident without examining all evidences mentioned above. Page 213 of 417  Annexure - 5/1 (Para 517) Typical Statement prepared in connection with an Oscillograph car run are given below (Statement 'A' to 'C') STATEMENT 'A' Total length of Section: 232 kms Section: BBQ—KZJ Length recorded: 185 kms Loco No.................... Date of recording: 22nd March 2019 Type of Loco............. Oscillograph Results Station Yards (Peaks above Threshold values) SN Name of Yard Speed in Vertical Lateral remarks and Location Kmph acceleration g acceleration g 1 SRUR 100.. 0.26 FP-2 100 2 MCI 100 0.22 TP-1 100 0.22 TP-2 3 PPZ 105 0.20 FP-1 0.20 FP-2 4 BGSF 110 0.22 324/10-11 5 OPL 100 0.26 343/5- 6 HSP 100 0.20 TP-1 STATEMENT 'B' Date of recording 22nd March 2018 Section: BPQ—KZJ (km 367- km 135 Loco No.:................................ Length recorded: 185 km Type of Loco:............... Total length: 232 km Oscillograph Results in Places other than Station Yards Isolated Locations (Peaks above Threshold value) SN Location Speed in Kmph Vertical Lateral Remark acceleration g acceleration g 1 146/1-2 100 0.28 Curve 2 148/15-16 110 0.28 Br 3 149/7-8 110 0.28 4 149/7-8 110 0.35 Br 5 151/8-9 110 0.24 6 151/8-9 110 0.32 7 151/11-12 105 0.24 8 160/7-8 110 0.22 Curve 9 164/9-10 110 0.24 10 168/1-2 100 And so on 0.30 STATEMENT 'C' Date of recording 22nd March 2018 Section: BPQ—KZJ (km 367- km 135 Loco No.:................................ Length recorded: 185 km Type of Loco:............... Total length: 232 km Oscillograph Results Active Continuous Stretches S Km Distan Speed Active Total Maxim No. of No. of Rema N From To ce in in in No of um peaks peaks rks km Kmph mode peaks value between above above 0.20 g. 0.30 g 0.20 g 0.30 g Nil Note – If there are on an average more than 10 peaks above the threshold value per km, the length may be included in this statement. 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