Track Geometry and Tolerances An over View On

Track Geometry and Tolerances An over View On Indian Railway

Track • Functions: • The main function of track is to transfer train loads to the formation and provide guide path • Geometry: • Each rail has 2 degrees of freedom • Both the rails, together have 4 degrees of freedom, define Track Geometry • X-level (cant), and Twist • unevenness, and alignment, • Gauge

DISTRIBUTION OF STRESSES • From Rail wheel contact stresses of the order of 10, 000 Kg/cm 2 to Ballast blanket contact stresses of the order of 0. 5 Kg/cm 2 i. e. at the top of the formation • AIM – To have a formation which is able to take repetitive load without any distress 3

Stress Distribution

Track Geometry • Vertical geometry • Lateral Geometry • Short wave rail geometry - weld defects, corrugations, wear - Rail profile and grinding

ISSUES INVOLVED Ø TRACK PARAMETERS Ø MEASUREMENT OF TRACK FAULTS Ø REPRESENTATION OF TRACK FAULTS Ø METHODOLOGY FOR SETTING STANDARDS Ø LEVEL OF TOLERANCES Ø TRACK QUALITY INDICES

Why Track Tolerances ? • Track is vital & costly asset • Track has to be laid to desired standards & then maintained not only for – Good riding comfort – Safety , – Longer life of asset. but also for • Quality control is essential while laying new track & subsequently for checking effectiveness of maintenance operations. • In Good system the maintenance operation are need based rather than periodic.

Why Track Tolerances ? • Therefore, it is necessary to lay down the limits of acceptable track parameters so that whenever these parameters are reached maintenance inputs can be planned. • In TMS system, the role tolerances will be predicting the deterioration of track based on past trend of 3 or more TRC run and planning deployment of track m/c. • Acceptance criteria for contractual work of track relaying.

Standards • Laying standards • Maintenance Standards – Comfort – Safety – Cost effective

Track Standards l Standard Deviation Based Tolerances For Speed >110 < 130 Kmph. For Speed < 110 Kmph. l Peak Based Tolerances For Speed > 100 < 140

What Track Tolerances? • • • New Track Tolerance Maintenance Tolerance Index Tolerance -> planned maintenance Service Tolerance -> urgent maintenance Slow Down Tolerance Safety Tolerance

New Track Tolerance • Highest level of track geometry that can be achieved on a new or relayed track with new material. • Best in terms of track quality. • Useful for controlling quality of track renewal, track relaying. • Should be practically achievable. • Nicely laid track results in lesser maintenance inputs & longer life of track assets besides resulting in savings in fuel consumption.

Maintenance Tolerances. • Next best tolerances after new track tolerances. • Standards to which the track should be brought after maintenance cycle. • Lower that new track tolerances & gap between them increases with passage of time due wearing out of track components. • Theoretically depends on age of track structure, cumm GMT carried, method of maintenance. • Level of track quality attainable after each maintenance cycle goes on reducing due to wear & tear of track components with time

Index Tolerances. • Tolerances at which planning for maintenance should be undertaken. • It takes care of delay between planning of maintenance and actual maintenance operation. • This ensures that service tolerances are not exceeded. • Fixed based on rate of deterioration and delay that can occur in sending a machine for maintenance.

Service Tolerances. • Standards upto which track parameters may vary in time during service. • Limiting standards that can be permitted in track at any time for max permissible speed to have the min acceptable level of riding comfort. • They always have certain safety margin from condition of derailment or fracture of any component of vehicle or track. • Track should be attended as soon as these limits are reached. • Most imp tolerance for maintenance Engineer.

Slow Down Tolerances. • If the track geometry deteriorates below service tolerance limits, speeds will have to be reduced to ensure min level of passenger comfort. =slow down tolerance. • Specifying these tolerances on high speeds is essential so that suitable speed bands are available on deterioration of track below service level.

Safety Tolerances. • These are limits beyond which dangerous/unsafe conditions arise for movement of rolling stocks. • Track geometry if maintained within tolerances for ride comfort, will automatically ensures safety as safety tolerances would be very slack compared service tolerances for min ride comfort. • Unsafe conditions not only depends on condition of track but also on type of vehicle, their riding characteristics & their maintenance standards. • Not specified on IR even on world railways.

New Tr. Tolerance Track Quality --> Maint. Tolerance Index Tolerance Service Tolerance Slow Down Tolerance Safety Tolerance Track Time --> Index Tol=Planned maintenance Tol Service Tolerance=urgent maintenance Tolerances Tol

New Tr. Tolerance Maint. Tolera nce TRACK QUALITY Deterioration Index Tolerance Service Tolerance Maintenance Inputs Slow Down Tolerance Safety Tolerance TIME in Years

Track Tolerance on I. R. • New Track Tolerance – Item 786 of 59 th TSC; – Para 316 of IRPWM • Maintenance Tolerance – Acceptance criteria (RDSO letter no. TM/HM/O dt. 28. 1. 93). Also , now in table 3. 1 of track machine manual ) ; – TM 115 • Index Tolerance. – Item 785 of 59 th TSC • Service Tolerance – C&M-1 (Rly. Bd. Letter no. 71/W 6/HS/1 dt. 21 -10 -71) – CS No 45 -Para 607(2) IRPWM for speed 100 to 140 Kmph – Item 785 of 59 th TSC. ; TM 115 • Slow Down Tolerance – For Unevenness & Twist parameter for 4 -wheeler (CRT)

Safety Tolerance=> NO SAFETY TOLERANCE • Para 607(3) of IRPWM • RAIL WHEEL interaction is a complex phenomena • Safety Tolerances for maintenance of track alone can not be prescribed in ISOLATION alone • Tolerances in para 607(2) and elsewhere TO MAINTAIN TRACK GEOMETRY FOR GOOD RIDING COMFORT

Correction Slip No. 96 of IRPWM para 607(3) The stability of trains against derailment, depends upon several factors such as track geometry, vehicle characteristics & 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 tolerances for track alone cannot be prescribed in isolation. With this in view, 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 provision and tolerances mentioned in Para 607(2) and elsewhere in this Manual are with a view to maintain track geometry for good riding comfort.

Track Standards Track Laying Standards as per IRPWM (Para-316) (a) Gauge Sleeper to sleeper variation + 2 mm (b) Expansion gap Over average gap worked out by recording 20 successive gaps + 2 mm (c) Joints Low joints not permitted High joints not more than Square-ness of joints on straight + 2 mm + 10 mm (d) Spacing of sleepers With respect to theoretical spacing + 20 mm (e) Cross level To be recorded on every 4 th sleeper + 3 mm (f) Alignment On straight on 10 m Chord On curves of Radius more than 600 M. On 20 m Chord. Variation over theoretical versine On curves of Radius less than 600 m On 20 m Chord. Variation over theoretical versine + 2 mm (g) Longitudinal level Variation in longitudinal level with reference to approved longitudinal sections. + 5 mm + 10 mm + 50 mm

Track Standards New Track Tolerances ( equivalent to TGI=100) Item no. 786 of 59 th TSC Parameter Unevenness Twist Alignment Gauge Chord/ Base (M) SD value for new track (mm) 3. 6 1. 20 9. 6 2. 50 3. 6 1. 75 4. 8 2. 50 7. 2 1. 50 9. 6 2. 50 - 1. 00

Gauge on Curves – BG – New Track (para 403 of IRPWM) S. Radius in meters No. 1. Straight including curves radius up to 350 M. and more Gauge 2. Up to +10 mm. For curves of radius less than 350 M of -5 mm. to +3 mm.

Maintenance Tolerance (Para 3. 1. 4, table 3. 1 of IRTMM) Acceptance criteria for Tamping of track As per Track machine manual Parameter <10 peaks Any peak Alignment ± 4 mm ± 6 mm X-Level ± 6 mm -Unevenness ± 6 mm ± 10 mm Note- (i)At least 4 stretches of 25 sleepers per km of tamped track should be recorded (ii) The versine and SE of curves for at least 10 stations should be recorded

MAINTENANCE TOLERANCES (TM 115) INDICES TGI Value 1. 60% CFD after tamping (to ensure quality of through tamping) (i. e. minimum 40% of track length after tamping should have TGI) >=115 2. 10% CFD after tamping (i. e. minimum 90% of track length after tamping should have TGI >=75

Tamping Frequency (Latest Instructions)

Tamping Frequency (Latest Instructions)

Index Tolerance (SD Form) Item 785 of 59 th TSC Index tolerance=Planned maintenance Tolerance

REVISED SD BASED INDEX TOLERANCES (Priority-II) Parameter Chord/ Up to 110 KMPH Base (M) (<105) > 110 <=130 KMPH (>105) Unevenness Twist Alignment Gauge 3. 6 2. 5 (3. 0) 2. 3 (3. 0) 9. 6 6. 5 (6. 5) 5. 1 (5. 5) 3. 6 3. 8 (3. 8) 3. 4 (3. 4) 4. 8 4. 2 3. 8 (3. 7) 7. 2 2. 7 (2. 8) 2. 3 (2. 8) 9. 6 5. 0 3. 3 (4. 0) - 2. 5 (2. 9) 1. 8 (2. 9) • Figures in brackets are SD as per 59 th TSC Meeting and followed till july 2007

Service Tolerances - CS No 45 -Para 607(2)IRPWM for speed 100 Kmph to 140 Kmph Isolated- 10 locations in a Km

Service Tolerance : Gauge as per para 224, 2(e) of IRPWM • On straight • On curve with v v -6 mm to +6 mm radius 350 m or more -6 mm to +15 mm radius less than 350 m upto +20 mm Note- Although uniform gauge over a long stretch is desirable

Limitations of CS 45 Tolerance • Not Applicable for sections having speed less than 100 Km/h. • Alignment parameter is restrictive ( at the time of study alignment was recorded manually ie in floating condition) • The chords are different from what is being presently used. Short Chords used for UN & AL was 3. 5 m & 7. 5 m against now being used 3. 6 m & 7. 2 m respectively. • The C&M-1 tolerance being peak based can have better correlation with acceleration peak and not Ride Index

Service tolerances for curves for ROC As per CS No 90 -Para 421 IRPWM Whichever is more For realignment of curves: Local adjustments may be resorted to in cases where the variation of versines between adjacent stations is only at few isolated locations. If more than 20% of the stations are having versine variation above the limits prescribed, complete realignment of the curve should be planned within a month.

Service tolerances for curves for ROC As per CS No 136 -Para 421 IRPWM Speed range Below 140 & upto 110 kmph Below 110 & upto 50 Kmph Below 50 Kmph Limits of station to station variation(mm) 10 mm (15 mm for speed of 110 kmph) or 20% of av. Ver. 20 mm or 20% of av. Ver 40 mm or 20% of av. Ver

For realignment of curves: • Local adjustments may be resorted to in cases where the variation of versines between adjacent stations is only at few isolated locations. • If more than 20% of the stations are having versine variation above the limits prescribed, complete realignment of the curve should be planned within a month.

Service Tolerance (SD Form) • Item 785 of 59 th TSC Service Tolerance= Urgent Maintenance tolerance

REVISED SD BASED SERVICE TOLERENCES (Priority –I) Parameter Chord/ Base (M) Up to 110 > 110 <=130 KMPH (<105) KMPH (>105) Unevenness 3. 6 3. 3 (3. 6) 3. 0 (3. 6) 9. 6 7. 4 (7. 2) 6. 2 (6. 2) 3. 6 4. 2 (4. 2) 3. 8 (3. 8) 4. 8 5. 0 4. 5 (4. 5) 7. 2 3. 8 (3. 0) 3. 0 (3. 0) 9. 6 6. 3 4. 0 (5. 0) - 3. 6 (3. 6) 2. 6 (3. 6) Twist Alignment Gauge • Based on RDSO’s report No. TM-109 circulated vide Railway Boards letter No. 2007/Track. III/TK/7 dated 12 -07 -2007 • Figures in brackets are SD as per 59 th TSC Meeting and followed till july 2007

SERVICE TOLERANCES FOR THROUGH PACKING DECISIONS (TM 115) S. No. Indices: 60% CFD before tamping (to decide to give machine TGI Value for through tamping) 1. Speeds >than or equal to 110 Kmph <=90 2. Speeds less than 110 Kmph <=80

REVISED SD BASED TRACK STANDARDS Parameter Chord/ Up to 110 KMPH Base (M) (<105 kmph) Unevenness Twist Alignment Gauge > 110 <=130 KMPH (>105 kmph) Priority II Priority I 3. 6 2. 5 (3. 0) 3. 3 (3. 6) 2. 3 (3. 0) 3. 0 (3. 6) 9. 6 6. 5 (6. 5) 7. 4 (7. 2) 5. 1 (5. 5) 6. 2 (6. 2) 3. 6 3. 8 (3. 8) 4. 2 (4. 2) 3. 4 (3. 4) 3. 8 (3. 8) 4. 8 4. 2 5. 0 3. 8 (3. 7) 4. 5 (4. 5) 7. 2 2. 7 (2. 8) 3. 8 (3. 0) 2. 3 (2. 8) 3. 0 (3. 0) 9. 6 5. 0 6. 3 3. 3 (4. 0) 4. 0 (5. 0) - 2. 5 (2. 9) 3. 6 (3. 6) 1. 8 (2. 9) 2. 6 (3. 6) • Based on RDSO’s report No. TM-109 circulated vide Railway Boards letter No. 2007/Track. III/TK/7 dated 12 -07 -2007 • Figures in brackets are SD as per 59 th TSC Meeting and followed till july 2007 • For spot exceedences based limits those given in Para 607 of IRPWM to be continued • Priority I; Urgent maintenance and Priority II is planned maintenance

Limitations of SD based Tolerance • Not available for all speed band • Critical value is corresponding to WDM 2 • Value for alignment parameter is too tight, corrected in July 2007, after TM 109, SD for AL 1 relaxed from 3 to 3. 8 for speed upto 110 kmph for priority –I (urgent maintenance).

CFD • Statistical Glossary • Cumulative Frequency Distribution: A cumulative frequency distribution is a summary of a set of data showing the frequency (or number) of items less than or equal to the upper class limit of each class.

What is CFD 60% • TGI values in increasing order for a SE(P. Way)’s section • 56, 58, 59, 63, 64, 65, 66, 68, 69, 71, 73, 75, 76, 78, 82, 85, 86, 89, 91, 93, 94, 95, 97, 99, 105 v. CFD 60%= v. CFD 10%=

Cumm Frequency Diagram. . . Plot of CFD vs TGI Frequen Cumm. % CUMM. cy Frequency FREQUENCY Cumm. % CUMM. Frequency FREQUENCY TGI Frequency 76 1 16 53 78 1 17 57 82 1 18 60 85 2 20 67 86 1 21 70 89 1 22 73 91 1 23 77 56 1 1 3 58 2 3 10 59 1 4 13 63 1 5 17 64 2 7 23 65 1 8 27 66 1 9 30 93 1 24 80 68 1 10 33 94 2 26 87 69 1 11 37 95 1 27 90 71 1 12 40 97 1 28 93 73 2 14 47 99 1 29 97 75 1 15 50 105 1 30 100

% CFD vs TGI 100 90 80 % C F D 70 60 50 40 30 20 10 0 50 60 70 TGI 80 90 100 110

RATIONALISATION OF TAMPING REQUIREMENTS S. No. INDICES (Speeds >than or equal to 110 Kmph < 130 Kmph) TGI Value 1. 60% CFD before tamping <=90 2. 60% CFD after tamping (i. e. minimum 40% of track length after tamping should have TGI) >=115 3. 10% CFD after tamping (i. e. minimum 90% of track length after tamping should have TGI) >=75 S. No. INDICES (Speeds less than 110 Kmph) TGI Value 1. 60% CFD before tamping <=80 2. 60% CFD after tamping (i. e. minimum 40% of track length after tamping should have TGI) >=115 3. 10% CFD after tamping (i. e. minimum 90% of track length after tamping should have TGI) >=75 • Based on RDSO’s report No. TM-115 circulated vide Railway Boards letter No. 2007/Track. III/TK/7 dated 16 -01 -2008

Slow Down Tolerance RDSO Letter No. CRA 501 dated 29 -4 -83

Limitations for Slow Down Tolerance • There is no mention in the compendium or in IRPWM. • No cognizance by other departments. • It should be for other stocks also. (These are for CRTs only).

Transmark Tolerances • Railway Board appointed a consultant for suggesting track tolerances for various speed bands (Planned, urgent and Maxm. ) • Did a lot of trials along with RDSO and submitted final recommendations in 1998 • The recommendations have not been accepted by Railway Board.

Transmark Tolerances Speed km/h From To Unevenness 9. 6 m Chord Alignment 7. 2 m Chord Twist 3. 6 m base Plann ed Urgent Max 0 60 5. 3 7. 2 9. 7 3. 3 4. 2 5. 5 3. 0 3. 7 4. 5 60 70 5. 2 7 9. 4 3. 2 4. 2 5. 4 3. 0 3. 6 4. 4 70 80 5 6. 8 9. 1 3. 1 4. 0 5. 2 2. 9 3. 5 4. 3 80 90 4. 9 6. 6 8. 8 3. 0 3. 9 5. 1 2. 9 3. 4 4. 2 90 100 4. 7 6. 4 8. 6 2. 9 3. 8 4. 9 2. 8 3. 4 4. 1 100 110 4. 6 6. 2 8. 3 2. 9 3. 7 4. 8 2. 8 3. 3 4. 0 110 120 4. 5 6. 1 8. 1 2. 8 3. 7 4. 7 2. 7 3. 3 3. 9 120 130 4. 4 5. 9 7. 9 2. 7 3. 6 4. 6 2. 7 3. 2 3. 9 130 140 3. 8 5. 1 6. 8 2. 5 3. 2 4. 0 2. 5 2. 9 3. 5 140 150 3. 3 4. 4 5. 9 2. 3 2. 8 3. 6 2. 3 2. 7 3. 2 150 160 2. 9 3. 0 5. 2 2. 0 2. 6 3. 3 2. 2 2. 5 3. 0

METHODOLOGY FOR SETTING STANDARDS • STATISTICAL ANALYSIS-CTR, TGI index • CORRELATION WITH VEHICLE RIDE • ECONOMY / MAINTAINABILITY

Ride Quality Correlation: • C & M 1 Report for Introducing trains at speeds beyond 110 Kmph(1969) • SD Based Studies considered in 59 th TSC • Transmark U. K. Studies on IR for Higher Speeds (1992 - onward), Inertial based Recordings to generate absolute profiles and correlation between different parameters.

Ride Criterion Correlation between Track Parameters & Ride Parameters Unevenness Vs Vertical Acceleration Vs Vertical Ride Index Vs Off-Loading & On-Loading Alignment Vs Lateral Acceleration Vs Lateral Ride Index Vs Lateral Force Twist Vs Off-Loading

Correlation Analysis

Methodology for fixing tolerances • All tolerances have to be laid down keeping in view the track vehicle interaction phenomenon. – So that high degree of correlation between track irregularity & vehicle ride is obtained. • Parameters for UN & AL to be arrived based on ride index & peak acc in vertical & lateral direction. • TW parameter is based on offloading of wheels. • Same method was adopted while C&M-1 report was prepared & peak based tolerances were fixed.

Contd. . • For S D based system we need new track & service tolerances. • Actual values of SDs on selected routes taken as samples out of which best 5% separated out from remaining 95%. • New track tolerances fixed as average value of 5% best track.

Contd. . • Index tolerances & service tolerances were fixed for following values of Ride Index for different rolling stock. • Limiting RI values: items 785 of 59 th TSC. Rolling stock Service Limit Urgent maintenance Limit Loco 4 4. 25 Wagon 4. 5 4. 75 COAC 3. 5 3. 75

• Fixing right tolerances of different kinds will help field engineer to monitor the track geometry properly. • It will economize min cost & increase the life cycle of the track.

Thanks

Transmark Tolerances

Transmark Tolerances

Transmark Tolerances

Transmark Tolerances

Transmark Tolerances

Transmark Tolerances

UIC Maint. Tolerances Ref. UIC/CEN/TC 256/SC/WG +2