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IMPLICATIONS AND SOLUTIONS FOR RUNNING OF 30 TONNE AXLE LOAD ON

DEDICATED ROUTES OF INDIAN RAILWAYS

1.0 INTRODUCTION:

1.1 General

The Indian economy enters the tenth plan with an expectation of 6% to 7% annual growth in the GDP and consequently 7.2% to 8.0% growth in the transport sector. These expectations place heavy demands on the already saturated road and rail transport system which coupled with the inadequacies in the power sector could be a major constraint in the realisation of the projected economic growth. With Airways, Coastal Shipping and Inland Waterways being in the fringes, freight transport in India is basically shared between Road and the Rail sectors. The road network in India has grown from 4-lakh km. in 1951 to over 30-lakh km now second largest in the world. Post independence the Railways made a flying start almost doubling the transport output in the first 5 year Plan. There was however a perceptible slowing down from 1968 to 1980 followed by a revival in the last two decades.

1.2 Wake up Call Freight Traffic has grown 90 times from 5.5 BTKM in 1951 to

over 500 BTKM now. Passenger Traffic has grown 80 times from 23 to 1800 BPKM in

the same period. National and State Highways comprising only 8% of the network

carries 80% of the traffic Railway share of Freight Traffic has declined from 89% in 1951

to 38% now. Golden Quadrilateral Road Network and Induction of Multi Axle

Road Vehicles will make a serious dent Even heavy duty Bulk Transport may not remain the exclusive

preserve of the Railways.

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1.3 Comparative Evaluation of Indian Railways with advanced Railways;

THE world's heaviest and longest freight train runs in Australia. With a payload of 82,000 tonnes and gross load of 99,734 tonnes, the train is formed of 682 wagons, hauled by eight 6000 HP diesel locomotives.

The 7.2- km train transfers minerals in bulk from one part of Australia to another crossing thousands of miles of largely uninhabited and desert areas. Theoretically, just 18 such trains are enough to carry the entire volume of about 1.5 million tonnes of freight moved every day by the Indian Railways, which deploys 5,000 trains of varying capacities to do the job. A comparison of the Railway Systems in China and India makes interesting study. In the decade 1992 to 2002 the route Km on the Chinese Railways (CR) has grown from minus 6% to plus 14% in comparison to that of the Indian Railways (IR). The two Railways carried almost the same volume of Passenger Traffic both in 1992 as well as 2002. However, in respect of Freight Traffic, the volume carried by CR is four and a half times that of India. They have achieved these results through more efficient exploitation of track, locomotives and wagons, and by assigning lower priority to passenger services. China has a larger proportion of double line and has adopted automatic signalling more aggressively than India. As a result, CR operates roughly twice the number of trains on electrified double line tracks than the Indian Railways

The Chinese Railways are planning an investment of US $ 200 billion in the mega plan period from 2004 to 2020, basically aimed at network expansion, doubling and creation of dedicated Passenger and Freight Corridors. .

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Integrated Railway Modernisation Plan (2005-10) has been made which has objective to enhance capacity, improve rail-port connectivity, higher axle load wagons to carry bulk material and development of dedicated freight corridors, two intercity, corridors Delhi-Patna-Howarh and Delhi Channai to be developed to run 150 Kmph trains using latest technology high speed coaches

And running of freight train @100Kmph on the high density Golden Quadrilateral and its diagonals connecting the four metropolitan cities. At present predominantly running axle load on Indian railway system is 20.32 tonnes are operating. Heavier axle Loads will enable carrying more payload in one train, which in turn improve throughput substantially.

Hence before a Heavier axle load is permitted to run, the safety of infrastructures has to be ensured as it carries passenger traffic also.

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Introduction of wagons, which can carry increased loads, is one of the answers policy makers would look to. Integrated Modernisation Plan (2005-10) released by Railway envisages running freight trains with axle load of 22.9 t on selected routes. As a precursor to the ensuring heavier axle loads, Railway Board has taken decision to run BOXN wagons with CC+8+2 loading on iron ore routes. This would result in axle loads of the order 22.82t and TLD of 8.51t/m.

In this scenario, introduction of trains with 30t axle loads probably is not quite far away. Incidentally, 30t axle loading happens to be heavy mineral loading standard. Running of such heavy axle load trains on the existing track would cause very high stresses on the track structure which would have far reaching implications on the requirements of track components and their maintenance and life.

1.4.1 Enhance Transport Capacity

We are in Transport business. Trailing loads and operating speeds are our principal efficiency indicators. Within the limitations of a loop length of 686 meters and the existing and proposed Track Loading Density of 7.67 and 8.25 tonnes per meter the options are

Higher Axle Loads

*With CC+2t

Increasing number of Axles per Wagon 11 % higher throughput with 23t Axle Load and 20 % with 25t Axle Load

can be achieved. With introduction of 30t axle load throughput will increase by 30% approx.

With 25 t Axle Load Track Loading Density would need to be relaxed to 8.8 t/m and 10.58 t/m for 30t axle load.

Rail Wear already a matter of concern and may be aggravated by higher Axle Loads.

Higher operating speed may not be possible with higher Axle Loads.

To carry more, cost effectively Railways must raise axle load

The axle loads running on the Heavy Haul routes of American, Australian, china and other advance Railways are ranging from 30t to 40 t. However there is major difference in Scenario prevailing on Indian Railway as unlike the World Railways where Heavy haul freight trains run on a dedicated Heavy Haul lines, in Indian Railway same infrastructure has to carry both goods and passengers traffic. Golden Quadrilateral and its two diagonals constituting 16% of Route Km (25% of running track Km) carry 55% of passenger and 65% of Freight traffic of the I.R. and are saturated on most lengths.

Axle Load in tonnes 20.32 22.9 25.0 30.0 No. Of Vehicles 58 58 58 58 Trailing Load in tonnes 4831* 5410 5800 6960 Track Loading Density t/m 7.67 8.25 8.82 10.58

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An attempt has been made in this paper to compute the stresses that would be induced in Rail, Sleeper, Ballast and Formation due to introduction of 30 t axle loads and the suitability or other wise of these components. Minimum track structure for running of these heavier loads and its impact on maintenance of P.Way is also dealt with. Implications for running 30 Tonnes axle load on dedicated freight corridor of Indian Railways and solutions to overcome the problems are also dealt with.

1.4.2 Dedicated Freight Corridors

The Freight Corridors should be constructed with the capability of carrying 30ton axle load Wagons (currently axle loads are limited to 20.3tonnes) in train formations of over 14,000t (presently train loads are about 4800 tonnes) hauled by multiple units of 4,000 to 6,000 H.P. ac/ac high tractive effort modern freight locomotives at speeds of 100 kmph. The loop lengths should be 1500 meters or longer to permit accommodation and crossing of train lengths of 120 wagons. While identification of Freight Corridors could be a matter of a detailed survey, the basic matrix could comprise: Connecting Collieries in Eastern and Central India with Power Houses in Northern and Western India. Connecting Iron Ore Mines with the Steel Plants. For example Bailladila, Dalli Rajhara-Bhilai Link and connection to Ports for Export. Connecting Ports of Western India with the focal point in Northern India for movement of double stack container traffic. At present Indian railway has taken up the project of running 30 tonne axle axle load between Deitari to Banaspani for a distance of 150 Km, which is a dedicated iron ore route in East Coast Railway.

Fewer wagons will be needed to haul the same load, leading to lower capital cost and possible reduction in wagon maintenance cost, fewer locomotives, lower fuel consumption per net tonne, reduction in train wagon kilometre operated, and fewer crew deployment entailing savings in wages. The railways in North America, Australia, South America, South Africa and Sweden have all increased axle loads to obtain significant savings in operating cost. These savings have been achieved despite increased cost of maintaining tracks, greater track component damages and shorter component lives.

The raising of the axle load from 22.5 tonnes to 30.5 tonnes yielded 40 per cent savings in transportation cost in the US. This in turn helped the railways in that country achieve significant reduction in operational cost of transporting containers and introducing customised wagons to win back traffic from the roadways.

Boosting wagon productivity, that is, how to carry more per wagon, or how to achieve higher payload per wagon, has become important for the Indian Railways in view of the increasing threat from the various other modes of transport, particularly roadways. Overall, the Railways now accounts for 38 per cent of the country's total freight movement compared to more than 80 per cent half a century ago. An analysis of the commodity-wise market share shows that between 1991-92 and 2000-01,

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there was a sharp drop in the rail coefficient for cement, POL, food grains and iron steel while it improved for coal, iron ore and fertilisers.

Also, while the drop has been significant, not so the extent of improvement. But, then, the lower axle load presents only one problem. There are several other problems that need to be tackled along with the raising of the average axle load. Thus, along with higher axle load, the track load density, that is, the maximum load permissible per metre length of track (TLD), too has to be increased. Any increase in axle load without corresponding increase in TLD will have a marginal effect on the throughput.

The other issues that also deserve careful consideration in this connection are track friendly bogies, smaller wheel size, and enhancement of maximum moving dimensions (MMD).

2.0 ASSESMENT OF TRACK STRUCTURE

On Indian Railway the strength of the for running various locomotives and rolling stocks at different speeds is assessed by calculating rail stresses induced locomotives/rolling stocks running at contemplated speed, using Civil Engg. Report No.C-100 rail wheel contact stresses on straight and curved tracks due to axle load combined stresses in rail head, foot, assuming rail wear of 5% are calculated on 52Kg rail and 60 Kg rail.

2.1. DESIGN OF RAIL SECTION:

2.1.1. RAIL STRESSES

Rail is a very important and costly component of the permanent way. Its failure will affect safety. Therefore, the rail is treated as a continuous beam on closely spaced elastic supports and the bending stresses are determined from the theory of Beam on Elastic foundation (BOEF). The fact that the rail is actually supported on sleepers at some distance apart introduces a very little error and is neglected. The maximum rail stresses calculated for 60 Kg rails with 100 Kmph speed are as under:

S.No. Rail Section Axle Load Track Structure Maximum Rail Stresses

1 52 Kg 30 t PSC, 1660 sleepers/Km, Ballast cushion 250

32.15 Kg/mm2

2 60Kg 30 t PSC, 1660 sleepers/Km, Ballast cushion 250

27.70 Kg/mm2

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Permissible Stresses 72 UTS 90UTS 19.25 (LWR) 25.25 (LWR) It can be seen from the above that even in 60 kg Rail stresses are higher than the permissible limit, in other words 60 kg 90 UTS Rail also not fit for 30 t axle loads.

2.1.2. Rail wheel contact Stresses

The contact between rail and wheel flange should be theoretically a point. Hertz theory explains that in practice the elastic deformation under higher axle lad results in deformation of steel of wheel and the rail creating an elliptical contact area. The dimensions of contact ellipse are determined by the normal force on contact area, while the ratio of ellipse axes a and b depends on the main curvature of the wheel and rail profile. Inside the contact area a pressure distribution develops which in a cross section, is shaped in the form of a semi-ellipse with highest contact pressure occurring at centre

The concentrated load between wheel and rail causes a shear stress distribution in railhead as shown in fig.

The contact problem is most serious in case of high wheel loads or relatively small diameters. Eisenmann has devised a simplified formula to calculate the maximum shear stress in rail head, which is as follow

Tmax =4.13(Q/ R)1/2

Where T max= maximum shear stress in rail head Q= wheel load +load due on loading due to curves.

R =Wheel radius (mm)

Since problem is one of the fatigue strength, the permissible shear stress is restricted to 30% of UTS, which works out to be 21.60Kg/mm2 for 72UTS rail and 27.00 Kg/mm2 for 90 UTS rails. The important deviation from the above formula is that the maximum shear stress increases with increase in axle load. It also increases with increase in curvature of

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track as increase super elevation results in increase on loading of inner rail when goods train ply on mixed traffic routes. The shear stress also increases with wearing of wheels as the wheel radius decreases with the wear of wheel. Thus it may appear that the problem of increase axle load can be solved with increase in wheel diameter but this is not possible as increase in wheel diameter means less carrying capacity because of restricted overhead clearances. Therefore only way to keep the maximum shear stresses within permissible limits is to use the rail with higher UTS. The contact stresses for BOY, BOB and BOXNHA wagons would be as under. The diameter of wheel of Casnub bogie is taken as average of new wheel and worn out i.e. (1000+925)/2=962.5 mm.

Wheel load Q ( tonnes)

Wheel load + 1 tonne

Worn wheel dia.(mm)

Contact shear stresses Kg/mm2

15.00 16.00 962 23.82

For 72 UTS rail the maximum allowable shear stress will work out to 21.60 Kg/mm2 and for 90 UTS rail, it will be 27Kg/mm2. It there implies that 90 UTS rail will be required for running 30 tonne axle load.

2.1.3 DESIGN OF SLEEPER

The load of the rolling stock from the rail would then be transferred to the sleeper. It is there fore essential that the sleeper be designed to the increased axle load of 30 Tonne .on Indian Railway, the lines on which Higher Axle Load would be probably be introduced are laid with PSC sleepers. Though these important routes are laid predominately with 60 Kg sleepers with either 60 kg or 52 kg Rails, there still exists long stretches of track with 52 Kg rails on 52 kg sleepers. The sleepers are laid mostly to a density of 1540 sleepers per Km though stretches where CTR is done in the recent past are laid to at 1660 sleepers per Km. An attempt has been made to calculate the stresses that would be exerted on sleepers due to the introduction of trains with30 T axle load for different combinations of sleepers and rails. In the design of the PSC sleepers, contact pressure between rail and sleeper at rail seat and the compressive stresses exerted by the sleeper on the ballast bed are the most important aspects to be considered of the several factors.

Important Design Criteria -

Contact Pressure Between Rail & Sleeper at Rail Seat Compressive Stresses Exerted by Sleeper on Ballast

CONTACT STRESSES BETWEEN RAIL & SLEEPER

As an extension to the Beam on Elastic on Elastic Foundation model proposed by Zimmerman for arriving at the stresses in the Rail, the contact pressure between rail

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and sleeper is computed based on based on the principle of discretely supported rail on springs at specified intervals. Using this principle and Dynamic Amplification Factor because of the dynamic interaction between rail and wheel due to the speed of train, the maximum bearing force on a single discrete rail support due to the wheel load is obtained from the formula Based on Beam on Elastic Foundation Model Bearing Force on Sleeper

Fmax = DAF * Pa/2 * (U/4EI)1/4 Where DAF = Dynamic Amplification Factor, which depends on the track quality,

the train speed and a multiplication factor of slandered deviation, depending on confidence interval.

P =Effective Wheel Load (T) a =Sleeper Spacing (Cm) U =Modulus of Elasticity of Rail Support or Track Modulus (Kg/Cm/Cm) E =Modulus of Elasticity of Rail Steel (Kg/Cm2) I =Moment of Inertia of Rail Section (Cm4)

Based on the charts developed by RDSO in their report no C-100 for different Rolling stock based on experimentation, the speed factor for BOX wagons for a speed of 100 Kmph comes to 1.68, However , since the wagon of 30 t Axle load would be different with different dynamic characteristics , the dynamic effect due to speed is also checked based on the formula proposed by Elisenmann for Dynamic Amplification factor As per Eisenmanns Formula, DAF = 1 + t {1+(V- 60)/140} t = Multiplication Factor Depending on Confidence Interval and = Factor Depending on Track Quality. For confidence t = 3, =0.2 for average track quality and 100 kmph speed,

DAF works out = 1 + 3 x 0.2 {1 + (100-60)/140} = 1.78 For 75 KMPH, DAF works out to 1.66 Speed factor of 1.68 is adopted for computation of stresses In the absence of relevant data regarding the type of rolling stock and the speed

that would be permitted for the purpose of computation of stresses on sleepers ballast and formation a speed factor of 1.68 is adopted based on the above computed values and RDSO.

For 30 t axle loads, the effective wheel load P would be 15t. The Mean Contact Pressure Between Rail and Sleeper on the most heavily

loaded sleeper would than be computed from the formula: - m. = (Fo + Fmax) / A

Where Fo = The total pre-tensioning force of fastenings on rail support (T)

A = Effective rail support area (mm2)

For concrete sleepers with elastic rail clips, Fo works out to =2x1, 000 =2000Kg = 2T for PSC Sleeper

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A would be 0.125 X the width of the rail foot, since the width of the grooved rubber pad used below the rail is 125mm.

For calculation purpose, it is normal to presuppose that the contact force is distributed evenly over the contact surface area.

The Contact pressure between rail and sleeper for 52 Kg and 60 Kg rail sections for 52 kg or 69 kg PSC sleeper and also for sleeper spacing of 60 cm and 65 cm computed basis on the above formulae are:

S No Rail Section Spacing Fmax(T) m. (N/mm2) 1 52 kg 65 cm 9.0830 6.4249 2 52 kg 60 cm 8.3843 6.0199 3 60 Kg 65 cm 8.3270 5.5077 4 60 Kg 60 cm 7.6865 5.1661 5 60 Kg 43 cm 5.5086 4.0046

Permissible contact pressure between the rail and sleeper for concrete sleepers is 4N/mm2.

But as seen from computations in the above table, contact pressure value at the rail seat for a track with 52 kg rail either on 52 kg or 60 kg sleepers would be far excess of permissible value when 30 t axle load rolling stock is introduced. Contact pressure are higher than the permissible value even for a track with 60 kg rail on 60 kg sleepers at 60 cm spacing. As computed above a track with 60 kg rail on 60 kg sleepers at 43 cm spacing only fit for running of 30 Ton axle load rolling stock from contact pressure criterion on PSC sleeper. This poses a very severe restriction, which would have far reaching implications and hence needs to be examined thoroughly before introduction of 30 t axle loads.

As illustrated in the in the formula for computation of bearing force on rail support, sleeper spacing proves to a relatively great influence on support force. Similarly, Use of heavier rails would reduce bearing force, where as increased support stiffness of track would result in increased bearing pressure on discrete sleepers. In the most unfavorable case, bearing pressure may be of the same order of magnitude as the effective wheel load P. This conclusively illustrates that maintenance of clean ballast cushion is essential to prevent damage to sleepers and to maintain track geometry when heavy axle load trains are introduced.

2.1.4 Stresses on Ballast bed

Ballast bed and formation are conceived as a two-layer system for the purpose of computation of stresses. Vertical forces on the ballast bed due to wheel loads will be considered as the determining stresses for the load bearing capacity of the layer system. Over loading of ballast bed due to increased axle loads causes rapid deterioration of the quality of the track when heavy axle load trains are introduced. The compresses stresses that the sleepers exert on the ballast bed are considered evenly distributed for the purpose of calculation. It means that the material from

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which the sleeper is made plays no role. The maximum stress between the sleeper and the ballast bed under the wheel load P is expressed based on Zimmermanns theory and by applying a Dynamic Amplification Factor due the speed of the Rolling stock as per Eisenmanns model.

sb = { DAF* Pa/2(U/4EI)1/4}/Asb

= Fmax/Asb Where Asb = Contact area between sleeper and ballast bed for half sleeper (mm2)

52 Kg and 60 kg sleepers differ only in respect of the distances between inserts so as to accommodate higher rail section and in all other respects, they are identical. Hence, there would be no difference in ballast stresses due to the use of either sleeper and the half sleeper contact area works out to 336,875mm2. Stresses on the ballast bed due to the force on sleeper, competed for 52Kg and 60 Kg rail sections and different sleeper spacing are tabulated as under:

S.No. Rail Section Sleeper Spacing

Fmax (T) sb (N/mm2)

1 52 Kg 65 cm 9.0830 0.2696 2 52 Kg 65 cm 8.3843 0.2489 3 60 Kg 65 cm 8.3270 0.2472 4 60 Kg 60 cm 7.6865 0.2282 5 60 Kg 43 cm 5.5086 0.1635

The permissible contact pressure on the ballast bed is taken as 0.50 N/mm2. As seen from the values in the above table, for the present track structure, stresses on the ballast bed would be whining the permissible value when 30 tonne axle load rolling stock is introduced. It can be gathered from the above equation that sleeper spacing and the extent of ballast support area have an important influence on the mean stress on ballast bed. A high value for foundation leads to high value of stress on ballast bed, whereas heavier rail profile has a positive effect in this respect. A heavier rail profile has a greater influence on rail stress reduction. The effect of ballast stress however, is approximately half of the effect on the rail stress.

2.1.5 STRESSES ON FORMATION

The loads from rolling stock are finally transferred to the formation through the ballast cushion, where the ballast bed and the formation are conceived as a two-layer system. Introduction of higher axle loads results in imposition of increased compressive stresses on the formation. This would lead to faster deterioration of track and call for more frequent maintenance schedules. The compressive strength on formation should be always kept whinin the bearing capacity of the formation, which depend on the modulus of elasticity of the formation apart from other geo-technical characteristics of the soil. The stresses transmitted to formation primarily depend upon the depth of ballast cushion and the effective bearing length of the sleeper. From the criteria of the force

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on individual sleeper due to axle load, compressive stresses on the formation are calculated from the following formula.:

Pmax = DAF. Pa/ DL. (U/4EI)1/4 = Fmax. (2/DL) Where, D= Depth of ballast cushion (mm) And L= Effective bearing length of sleeper at rail seat (mm). For PSC sleeper, L is taken as 1040mm. Formation stresses for 52 Kg & 60 Kg rail sections and ballast cushion of 250mm & 300mm, on account of introduction of 30t axle Load, computed based on the above formula are tabulated below:

S.No. Rail Section

Sleeper Spacing

Fmax

(T)

sb (N/mm2) 250 mm

sb (N/mm2) 300 mm

1 52 Kg 65 cm 9.0830 0.2223 0.1853 2 52 Kg 65 cm 8.3843 0.2052 0.1710 3 60 Kg 65 cm 8.3270 0.2038 0.1698 4 60 Kg 60 cm 7.6865 0.1881 0.1568 5 60 Kg 43 cm 5.5086 0.1348 0.1124

The modulus of elasticity and permissible stresses on the formation for 2 million cycles of loading as indicated by Coenraad Esveld are reproduced below:

S.No. Classification E (N/mm 2) (N/mm2) 1 Poor 10 0.011 2 Poor 20 0.022 3 Moderate 50 0.055 4 Good 80 0.089 5 Good 100 0.111

Obviously, with introduction of 30 tonne axle load rolling stock, in most cases, formation stresses would exceed the bearing capacity of the formation.

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3.0 IMPLICATIONS AND SOLUTIONS FOR RUNNING OF 30 T AXLE LOAD ON EXISTING TRACK

3.1 IMPLICATIONS ON RAILS:

3.1.1. Increased Contact Stress & Early fatigue Failure If the permissible stresses are exceeded there will be plastic flow of metal at contact and development of cracks in railhead will take place. These cracks grow gradually due to combined effect of contact stresses with the entrapment of water or lubricant resulting is surface breaking. If allowed to grow, they have potential go subsurface and cause a failure by combining with already present defect. Another implication is that if the surface cracking is severe, the substantial amount ultrasonic waves transmitted will be reflected from these surface defects making it impossible for the rail section to be reliably inspected for full depth. The most prominent defects with the heavy haul are Rolling Contact Fatigue defects predominantly the Gauge Corner Fatigue.

The maximum shear stress is developed not on the contact surface but at a depth of 5-7mm below the railhead. It therefore implies that use of head hardened rails will be effective only if such hardening increases the UTS up to the depth of 6 mm or more from the railhead. It is interesting to know the effect of surface hardening and lubrication in context of maximum shear stresses. If wear is not dictating the life of rail, as on head hardened rail / lubricated rails, the maximum repetitive shear stress will always occur at same point, thereby increasing propensity of fatigue failure and shelling. On the other hand if the rail is allowed to wear, the point of occurrence of maximum shear stresses will gradually shift downwards making it less prone to shear fatigue failures or shelling. Therefore, it is paradoxical to say whether the use of head hardened rails / lubrication of rails will actually enhance or reduce the life of rails with heavy haul. Tests at Facility for Accelerated service Testing (FAST) have also shown that higher wear rates of rail not only reduce surface defects but also suppress the internal defects i.e. detail fractures and shelling.

RAIL FATIGUE LIFE:

From the analysis of bending stresses and contact stresses it may though appear that 52 Kg 90 UTS rail may suffice the requirements of increased axle load, but in practice, the above stresses coupled with thermal stresses and residual stresses set up cyclic stresses. From the theory of fatigue, it is evident that such cyclic stresses may result in failure of material at a stress level lower than what would normally require for failure. Allan M Zarembski compared the rail life based on wear limits to rail fatigue life for different axle loading environment and found that in lighter axle loading environments, rail wear is dominant mode of failure while in heavier axle load environments, the fatigue emerges as dominant replacement criterion.

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Rail Fatigue Life vs Wear 136 RE Rail AREA Bulletin No. 685, Vol 83 reports of study made by Dr. Allan.M.Zarembski on the effects of increasing axle loads on tangent track on a continuous welded track. Two independent studies were conducted to determine the fatigue life of rails with different axle loads. The first study involved the study of rail defect data to obtain the probability distribution curves. Analyses of rail defects have shown that the probability of their occurrence is a function of tonnage (MGT) and it follows Weibull Distribution. The cumulative defect data was found to have linear relationship with the accumulated MGT when plotted on Weibulls scale. The defect datas collected from two mining railroads operating with different axle loads and compared with those of a mixed railroad. The results have shown that heavier axle loads have resulted in a more severe occurrence of rail defects.

Figure 8: Cumulative Probability Distribution

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The second study was the analysis of the rail life under fatigue. The effect of traffic load, calculated rail head stresses (Bending, contact, thermal and residual stresses), material properties of rail steel were analysed using the cumulative damage fatigue theory which postulates that every increment of stress beyond the fatigue strength of material causes fixed amount of damage. The fatigue lives of rails were then calculated for different types of service environment. The study had two conclusions: 1). An increase in axle loading will result in decrease in the fatigue life of rail, measured in terms of cumulative MGT and reduction occurs for both heavier as well as lighter sections. ii). When the axle loads are increased from 27.5 tonnes to 33 tonnes (corresponding to 70 tonnes and 100 tonnes freight cars), the resulting decrease in life of rail was found to be 40 %. Thus under Indian Railways context, it can be said that with increase in axle load upto 25 tonnes, 52 Kg/m, 90 UTS rail may even though be permitted from the considerations of bending stresses and contact stresses, however, in the interest of long term economy and from fatigue considerations, it will be more appropriate to use a heavier section of 60 Kg/m if further increases in Axle loads are imminent.

SOLUTIONS 3.1.2 RAIL GRINDING

A better solution to increase the life of the rails on Heavy Haul Routes is rail grinding. Such grinding will remove the plastic deformation on railhead thereby removing the surface cracks before they propagate further into rail section. It also helps in progressively lowering the point of maximum shear stresses thereby increasing the life of the rail and prevention of sub surface cracks due to fatigue. Rail grinding is done primarily to

1. Shift the wheel loads from the gauge corner of running rail surface by asymmetrical grinding pattern.

2. Prevent area of high- localised stress by grinding the corrugated profile to confirm to wheel geometry.

3. Grinding at predetermined intervals shifts the critical internal stresses, thereby not allowing micro cracking and subsurface failure to occur.

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Rail grinding removes the plastic deformation on rail head- helps in progressively lowering the point of maximum shear stress thereby increasing the fatigue life of rail

Prevent areas of high localized contact stresses by grinding the corrugated profiles more conforming to wheel geometry, thereby distributing internal stresses more uniformly, into the rail cross section

Grinding of rails using LORAM SX-11 rail grinder has been done on Kottavasla Kiramdul line, which has shown reduction in rail wheel contact stresses and consequent failures.

On curved track with heavy haul traffic - pronounced side wear on outer rail, gauge face corner defects

Flattering of rail head due to plastic flow of material on inner rail

The grinding not only makes the operation of heavy haul safer but also brings about a long-term economy. It has been demonstrated on Swedens iron ore line, the Malabanan, that by preventive grinding over a period of 3 years, the Rolling Contact Fatigue defects were considerably reduced. The Malmbanan is claimed to be Western Europes only heavy haul line insofar as it carries fairly long trains with relatively high axle loads of 25 tonnes and relatively high annual tonnage of about 23 GMT. The line suffered from the problem of RCF defects like stalling, shelling and head checking. These defects were primarily observed on the high rail of curves and in switches and were a cause of considerable concern. A preventive grinding strategy was adopted where the rate of metal removal was about 0.20 mm across the railhead after every 23 GMT. By adopting this preventive grinding, the cost of rail grinding and rail decreased by more than 30 %. The principal savings came from the purchase of rails, which declined, by two thirds over the period 1997-99, from over 6 million crowns to about 2 million crowns, while the cost of grinding remained constant at about 5 million crowns. Thus the Railway was not only less expensive but also safer.

02468

1012

1997 1998 1999 2000

Cost of Rail, Rail grinding and total cost Malmbanan 1997- 2000

Grinding costRail costTotal

Thus it can be concluded that the Grinding will be effective strategy both in terms of safety and long term economy, for the heavy haul routes as it helps in prolonging the life of costliest component of track, the rail.

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3.1.3 Effect on curvature and track geometry

ORE 161 studies reports that Dynamic effects of 22.5 tonnes axle loads for different speeds, track quality and radius of curvatures

Dynamic wheel force (DSQ) increases with increase in speed *The lateral rail- wheel force (Ya) increases with increase in curvature and deterioration of quality of maintenance. *Curves with radius sharper than 400m require a greater care of track geometry with increase in axle loads.

Poorly maintained track will have most pronounced effect, where increase in the wheel force can be up to 22 % of axle loads for speed ranging between 60 to 100 Kmph observed

Track quality was expressed in terms of standard deviation of vertical profile and alignment

2mm moderate

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SOLUTIONS

Head hardened rails should be used. Extra ballast profile should be given at curves. Lubrication of gauge faces should be done at closed intervals.

3.1.4 Effect of wheel flat

Relationship between the flat size and force is almost linear

On Indian Railways, the permitted sizes of wheel flats are 50mm for locomotives and coaching stock and 60mm for goods stock.

Size of flat will depend on diameter of wheel (c2/8R). No consideration for size of flat in specifications of wheel flat.

The largest loads applied to the track from vehicles are those, which arise from irregularities on wheel such as wheel flat. ORE 161.1/RP 3 reports of the tests carried out on flat tyres measuring the effects of speed, size, sleeper type and axle loads. The results reveal: I) The forces at frequencies above 500 Hz referred to as P1 forces increases continuously with speed, while the forces at frequencies below 100 Hz, referred to P2 forces are more of less independent of speeds. The P1 forces have bearing on wheel rail contact stresses. This force, which causes most of damage to rails and concrete ties, increases with increase in speeds.

ii). Increase of axle load from 20 t to 22.5 t (12.5%) caused the increased wheel flat force of the order of 0 to 6 %. Hence if go from 22.5t to 30 t the increase in wheel flat force will be of the order of 24%.

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Studies have also revealed that movement of wheels with flats can generate dynamic forces, as high as six times the normal static load, in extreme situations.

On Indian Railways, the effect of rail/ wheel defects and vehicle suspension, on static wheel load, is represented by a speed factor (Rail stress calculations), which can assume a maximum value of 1.75 for locomotives and 1.65 for wagons.

The problem assumes alarming proportions incase of thermit welds (which have the impact strength of 7-10% of parent rail) in LWR territories, during winter season, when the full tensile stresses are present in rail section.

Spate of weld failures due to running of flat tyres under these conditions, is not uncommon.

Studies have also revealed that movement of wheels with flats can generate dynamic forces, as high as six times the normal static load, in extreme situations. The Dynamic forces increase with increase in speed and axle loads. On Indian Railways, the effect of rail/ wheel defects and vehicle suspension, on static wheel load, is represented by a speed factor, which can assume a maximum value of 1.75 for locomotives and 1.65 for wagons. However the studies conducted by ORE shows that the dynamic loads can increase up to 6 times static wheel load and further by 6% due increase in axle loads. Such occasional high loads may result in higher rail

19

stresses reducing the fatigue life of rails and causing fracture of rail/ welds in extreme cases. The problem assumes alarming proportions in case of thermit welds (which have the impact strength of 7-10% of parent rail) in LWR territories, during winter season, when the full tensile stresses are present in rail section. Spate of weld failures due to running of flat tyres under these conditions, is not uncommon.

SOLUTIONS

Codal provisions of tolerances of flat wheel require to be changed. Monitoring of flat wheels should be done closely and en route detachment of wagons with flat wheels should be done. The US studies revealed that the defect size more than 15% have direct implication due to wheel flat and failure rate is more. The USFD should be carried out within the periodicity of 8GMT so that defects of sizes more than 15% shall be detected in time.

3.1.5 EFFECT ON RAIL/ WELD FAILURE

With increase in axle load, there will be increase in rail/weld failures. All the AT welds should be supported on wooden blocks and joggled fish plates should be provided. The patrolling in rail/weld failure area should be effected so ensure safety. The frequency of USFD testing should be increased with latest technology and should be done in the periodicity of 8GMT.

3.2 IMPLICATIONS ON SLEEPERS

The existing sleeper density of 1660 Nos/Km at spacing of 65 cm is not sufficient and may have center binding and other defects due to increase in stress level. Contact pressure is higher than the permissible value even for a track with 60 kg rail on 60 kg sleepers at 60 cm spacing. As computed above a track with 60 kg rail on 60 kg sleepers at 43 cm spacing only fit for running of 30 Ton axle load rolling stock from contact pressure criterion on PSC sleeper. This poses a very severe restriction, which would have far reaching implications and hence needs to be examined thoroughly before introduction of 30 t axle loads.

As illustrated in the formula for computation of bearing force on rail support, sleeper spacing proves to a relatively great influence on support force. Similarly, Use of heavier rails would reduce bearing force, where as increased support stiffness of track would result in increased bearing pressure on discrete sleepers. In the most unfavorable case, bearing pressure may be of the same order of magnitude as the effective wheel load P.

SOLUTIONS

Maintenance of clean ballast cushion is essential to prevent damage to sleepers and to maintain track geometry when heavy axle load trains are introduced.

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3.3 IMPLICATIONS ON BALLAST AND FORMATION

The permissible contact pressure on the ballast bed is taken as 0.50 N/mm2. As seen from the values in the above table, for the present track structure, stresses on the ballast bed would be whining the permissible value when 30 tonne axle load rolling stock is introduced.

Obviously, with introduction of 30 tonne axle load rolling stock, in most cases, formation stresses would exceed the bearing capacity of the formation. Blanketing is to be done for whish extra cost of 10 Lac/Km will be involved.

SOLUTIONS

This would necessitate provision of a blanket layer of adequate thickness to improve the bearing capacity just beneath the ballast bed. Provision of blanketing, in accordance with the recent guidelines issued by RDSO in June 2003 vide Guideline No. GE: G-1, appears to be the only solution for stabilising weak formations. It is obvious that a yielding formation will result in rapid deterioration of track geometry, which will make it unsafe of higher axle load trains in addition necessitating increased and frequent maintenance efforts.

o Provision of a blanket layer on running tracks under traffic, however is going to be a difficult task due to the obvious constraints such as availability of Engg. Time Allowance; line Blocks, restricted working space, safety implications, difficulty in completion etc.

J P Hyslip & E T Seli, S S Smith and G R Oleoft, have reported of Ground Penetrating Radar (GPR) being employed to assess conditions in railway track substructure (ballast, sub ballast, and sub grade) and to produce quantitative indices of substructure condition for use in track maintenance management efforts. GPR surveys have been conducted on over a combined 100 miles of track, including mainline and freight tracks. Results of these surveys have shown the ability of GPR to distinguish between the different substructure layer conditions to determine areas of trapped water and fouled ballast. The railway GPR equipment is mounted on a hi-rail vehicle and includes multiple sets of 1-GHz air launched horn antennas suspended above the track that permit fast survey travel speeds and high resolution measurements to a depth of 4 to 6 ft (1 to 2m). The antenna configuration and surveying procedures are deployed to reduce the influence of sleepers and rail. Antennae are located at both ends of the sleepers as well as in the centre of the track, so the variations of conditions laterally across the track are seen.

The GPR method requires transmitting pulses of radio energy into the subsurface and receiving the returning pulses that have reflected off interfaces between materials with different electromagnetic properties. Antennae are moved across an area with a continuous series of radar pulses, giving a profile of the subsurface. Reflections of the

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GPR pulse occur at boundaries in the subsurface where there is a change in the material properties. Only a portion of the pulsed signal is reflected and the remaining part of the pulse travels across the interface to again be reflected back to the receiver from another interface boundary. The time the pulse takes to travel through the layer and back is controlled by the thickness and properties of the material. The travel time between upper and lower boundaries of a layer can be used to calculate the layer thickness employing a known velocity.

3.4 IMPLICATIONS ON SEJS AND TURNOUTS:

SEJS will have higher impact loads resulting in pre mature failures. Design developed by Rahi Industries should be used for higher axle loads. There will be higher wear and tear of switches and crossings of turnouts. Thick web switches should be used in the turnout taking out of curve. CMS crossing should be used instead of built up crossing. Maintenance of fittings should be of highest order.

3.5 IMPLICATIONS ON MAINTENANCE OF TRACK 3.5.1 SWEDISH MODEL STUDY

S.Hammarlund, B. Paulsson, conducted Swedish model for prediction of maintenance costs when increasing axle loads from 25 t to 30 t. The paper shows that by increasing the axle load from 25t to 30t, the deterioration mechanisms on the rails was surface fatigue (60%), engine burns etc (15%), internal defects found by USFD (10%), actual rail and weld fractures and isolating joints (10%). Only 5% of the rail maintenance was found to be due to wear on this part of line. The expected increase of track maintenance cost was 3%, which is substantially lower than the increase in axle load (20%). The possibility to reduce the maintenance cost was suggested by doing rail grinding and better system of lubrication

3.5.2 AASHO TEST

Increase in the stress on the ballast bed due to increased axle loads would definitely result in faster deterioration of track geometry quality. Though the relation is still ambiguous, on the basis of AASHO Road Test for Road structures, it is assumed that; Decrease in track quality= (Increase in stresses on ballast bed) m Where the value of m is generally taken between 3 & 4. Thus, a 10% higher stress on ballast bed leads to 1.2 to 1.5 times faster reduction in track geometry quality and consequent proportionate increase in maintenance. Introduction of 30 tonne axle load rolling stock against the present loading of 20.32t would therefore result in the increase of track maintenance effort 3 times.

While running 30 t axle loads, impact stresses on the ballast will increase and this further lead to crushing of ballast. Therefore, deep screening of ballast is required at close interval of time.

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3.5.3 Findings of The AAR Panel on 100-Ton Cars

In 1981, an AAR panel of distinguished railroad engineers compared the expected impacts on 80 tonne loading cars (20 t axle loads) on well maintained tangent track with 60Kg rail continuous welded rail to the expected impacts of 263,000- pound cars 9100 ton loading cars) on the same track. The panel concluded that rail life would be 1.5 to 2.1 tonnes greater using the 80 ton cars, while tie and ballast life would be1.0 to 1.4 times greater under traffic loads. The panel report also noted that the impact of heavier 100-ton cars would be much greater on light rail and poorly maintained track. However these reports were not quantified. Findings of the Ahlf Study of 100-Ton Cars.

Robert Ahlf(1980) developed an economic Engg. Model of maintenance of Way and structure costs reported using class-1 railroad maintenance expenses and workload measures ( such as gross tonne miles). He classified each MW & S cost element into one of the three categories

1. Fixed cost 2. Cost that vary in relation to the mechanical actions of the track under load

and 3. Cost that vary with rail life. The cost of ballast, sleeper and track surfacing effects were included in category 2 above. Rail deflection was used as an indicator of the mechanical action of the track under different axle loads and track support conditioned.

SOLUTIONS Strict tolerances for the track parameters should be be kept. Maintenance inputs are required to be increased. Use of superior materials to increase the life cycle should be used. Mechanised maintenance should be adopted. Deep screening and temping should be done at closer interval than existing provisions.

3.6 IMPLICATIONS ON BRIDGES

It is required to be thoroughly checked the design of all the bridges in dedicated routes where 30 tonne axle load is to be introduced and make necesscery design changes as per HMLS loading. Necessary speed restrictions should be imposed on safety considerations. As per technical instructions no 4 (issued by Member Engineering Sh RR Jaruhar,) on Load carrying capacity of masonry Arch bridges, Test load application with observation or deflection, spread and residual deflection is more appropriate with limiting value deflection as 1.25 mm and spread as 0.38 mm as criterion. It is considered safe for all practical purpose to allow axle loads up to 30t with 60 Kmph speed with proper physical condition of arch being assured. Utmost, an additional ring can help fixed proper skewback on strengthened abutment / pier. Such bridges must be thoroughly examined.

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3.7 IMPLICATIONS ON SCHEDULE OF INSPECTION

With the increase in axle load to 30 t the schedule of inspections of officials and supervisors needs to have re look. Definitely frequency inspections will be increased.

3.8 USFD TESTING Frequency has to be increased. Use of Sperry tester should be done.

4.0 IMPLICATIONS AND SOLUTIONS FOR RUNNING 30 TONNE AXLE LOAD IN NEW TRACKS

The strategy for running heavy axle loads of 30 tonne should comprise of following alternative solutions;

4.1 Up gradation of the track, bridges and formation, to withstand the induced higher stresses on account of introduction of heavy axle loads wagon.

4.1.1 Design of Rail section:

The maximum bending stress in 6o Kg rail on introduction of 30 tonne axle load works out to be 27.70 Kg/mm2 for 90 UTS rails.

Permissible Stresses are 72 UTS 90UTS 19.25 (LWR) 25.25 (LWR)

It can be seen from the above that even in 60 kg Rail stresses are higher than the permissible limit, in other words 60 kg 90 UTS Rail also not fit for 30 t axle loads.

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The contact stresses for BOY, BOB and BOXNHA wagons would be as under. The diameter of wheel of Casnub bogie is taken as average of new wheel and worn out i.e. (1000+925)/2=962.5 mm.

Wheel load Q (Tonnes)

Wheel load + 1 tonne

Worn wheel dia. (mm)

Contact shear stresses Kg/mm2

15.00 16.00 962 23.82

For 72 UTS rail the maximum allowable shear stress will work out to 21.60 Kg/mm2 and for 90 UTS rail, it will be 27Kg/mm2. It therefore implies that 90 UTS rail will be required for running 30 tonne axle load.

The worlds longest rails are now manufactured in India for a length of 120m.

With the availability of 120 m long rails, there will be drastic reduction of weld population in Indian rail tracks (from 160 welds per track km presently to 17) resulting enhance safety and cost reduction.

4.1.2 DESIGN OF SLEEPER

As computed above with 60 kg rail on 60 kg sleepers at 43 cm spacing only fit for running of 30 Ton axle load rolling stock from contact pressure criterion on PSC sleeper. The 60 Kg Rail fails in bending stress criteria and 71 kg rail suits as next option. 71 kg rail is having foot width of 160 mm against availability of 162mm width of MS insert. This poses a very severe restriction, which would have far reaching implications and hence needs to be examined thoroughly before introduction of 30 t axle loads considering difficulty involved in maintaining track with such high density of sleepers i.e. 2326 sleepers/Km.

4.1.3 DESIGN OF BALLAST BED

The contact pressure on ballast for 60 Kg sleepers at spacing of 43 cm works out to be 0.1635 Kg/mm2. The permissible contact pressure on the ballast bed is taken as 0.50 N/mm2. For the present track structure, stresses on the ballast bed would be within the permissible value when 30 tonne axle load rolling stock is introduced. As per Railway Boards letter No.95/w1/Genl/0/39 dated: 9.10.96, the depth of ballast cushion for 30t axle load is 25cm with sub ballast of 15cm for speed up to 100 Kmph. However a clean ballast cushion of 300mm may prove best solution for running 30 t axle loads.

4.1.4 DESIGN OF FORMATION

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Obviously, with introduction of 30 tonne axle load rolling stock, in most cases, formation stresses would exceed the bearing capacity of the formation. This would necessitate provision of a blanket layer of adequate thickness to improve the bearing capacity just beneath the ballast bed. Provision of blanketing, in accordance with the recent guidelines issued by RDSO in June 2003 vide Guideline No. GE: G-1, appears to be the only solution for stabilising weak formations. It is obvious that a yielding formation will result in rapid deterioration of track geometry, which will make it unsafe of higher axle load trains in addition necessitating increased and frequent maintenance efforts.

4.1.5 DESIGN OF BRIDGES The bridges are required to of HMLS designs for carrying 30t axle load.

5.0 ALTERNATIVE STRATEGY: MODIFICATION IN WAGONS

5.1 Introduction of 3-axle bogie for increasing the pay load carrying capacity, while keeping the stresses on the track structure within permissible limits.

Increase in number of axle (3-axle bogie) is another strategy, which can be thought of for increasing the pay Higher tare loads of the wagons running on the Indian Railways as compared to those running on developed countries is one area where a possible solution to the problem of running increased axle loads lie. To cite an example of BOXN has the payload to tare ratio of 2.61. In most of heavy haul routes, this ratio varies from 3.5 to 5. TRANSWERK, South Africa has developed 104 t gondola tippler coal wagon with a 4.2 tare ratio and 120t tippler iron ore wagon with payload tare ratio. These options will be apparently more beneficial compared to the resource intensive up gradation of the track, bridges and formation, on account of introduction of heavy axle loads wagons.

We have opted for Broad Gauge (5 feet 6 inches between rails against the standard gauge world wide of 4 feet 8.5 inches) yet our moving dimensions are highly restrictive. Similarly, productivity of our wagons in terms of tare to pay load ratio is probably one of the poorest in the world. We carry 450 kg of dead weight for moving every tonne of traffic as against 170 kg in developed countries. The wagons should be redesigned to increase the cubic content and the load carrying capacity to fall in line with the international norms. No tippling for unloading should be resorted to. Wagons should be equipped with end of train telemetry. Coupling height should be 851 mm instead of 1105 mm at present. Lowering of wheel diameter and coupling height substantially increases the volume available for the payload Bogie Mounted Electronic Brake System should be adopted. Conforming to Liberalized Moving Dimensions

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5.2 COMMUNICATION INPUTS The communication system should be 880 Hz. GSMR permitting direct communication between Driver and Guard and the Section Control.

The signalling should be Cab Signalling with 1500 meters overlap

6.0 ON GOING PROJECTS FOR RUNNING 30 TONNE AXLE LOAD

At present Indian railway has taken up the project of running 30 tonne axle load between Deitari to Banaspani for a distance of 150 Km, which is a dedicated iron ore route in East Coast Railway. The track structure adopted in this project is 60 Kg 90 UTS rails on PSC-60 Kg sleepers of 1660 Nos/Km with a clean ballast cushion of 300 mm. At curves greater than 3 deg. 60 kg head hardened rails are used. However, the speed of the goods train is proposed as 75 KMPH. All the Bridges and formations are designed for High Mineral Loading Standards.

7.0 CONCLUSIONS

1. To carry more freight, cost effectively the Indian Railway must raise axle loads to 30 tonne.

2. From the consideration of bending stresses and contact shear stresses, even 60 kg, 90 UTS rail is not able to sustain the increased stresses due to 30 tonne axle loads. 68.5 Kg AAR or 71 Kg UIC rails seems to be a realistic solution.

3. Contact pressure between rail and sleeper would be higher than the permissible value even on a track with 60 Kg rail on 60 Kg sleepers (PSC-6) at 60 cm spacing (1660 sleepers/Km).

4. It is found that track with 60 Kg rail on 60 Kg sleepers at 43 cm spacing (2326 sleepers/Km would only be fit for running of 30 tonne axle loading from the consideration of contact stresses. Else, PSC sleepers will require redesigning considering the difficulties involved in maintaining a track with such high sleeper density.

300 mm clean ballast cushion would be required for running 30 tonne axle load and the deep screening and temping needs to be done at closer intervals.

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7. With the introduction of 30 Tonne axle load, in most of the cases, formation

stresses would exceed the bearing capacity of the formation. This would necessitate provision of a blanket layer of adequate thickness as per RDSOs specifications for which extra cost of Rs. 10 Lac/Km will be involved. For running 30t axle load in the existing track this will be most challenging job due to field difficulty in carrying out the work.

8. Each bridge in the dedicated corridor should be evaluated regarding safety vis--vis its physical condition and check for HMLS loading. Impose speed restriction, if necessary particularly in arch bridges.

9. The cost of the maintenance of the track with increase in axle loads from 20.32 t to 30 t is expected to increase by 3 times depending on the formation and track quality as per AASHO test. This is still ambiguous since Swiss model studies shows 3% increase in maintenance cost after doing rail grinding and lubrication.

10. Maintenance inputs are required to be increased. Rail grinding is to be carried out at predetermined intervals. Also lubrication must be carried out regularly.

11. For running the 30t axle load in existing track increase frequency of inspections , patrolling and USFD testing are required. USPD should be done in the periodicity of 8 GMT.

12. As an alternative strategy, use of wagons with high payload to tare ratio and increased number of axles may also be considered. Wagon dimensions must be changed with reduced wheel diameter. Signalling system requires to be upgraded.

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8.0 REFERENCES:

1. Esveld Coenraad, Modern Railway Tracks. 2. RDSO Guideline No. G-1, Guidelines For Earthwork in Railway Projects. 3. RDSO Civil Engg. Report No. C.55, Investigations on Determination of

Intensity of Pressure on Railway Formations- BG Tracks. 4. Eisenmann Dr. Ing. J., Vehicle- Track Panel- Ballast Stresses. 5. Harvey A.F., Sleeper Spacing and its effects on the Maximum Permissible

Axle Load. 6. Mohan M.S., Track Structure on heavy Mineral Lines. 7. International Heavy Haul Association, may 2001- Guidelines to Best

Practices for Heavy Haul Operations: wheel and Rail Interface Issues. 8. Tech. Paper No. 245: Report of Bridge Sub-Committee on track stresses,

1925. 9. Tech. Paper no.323- Stress in Rly track, by Venkatramaya, 1950

10. Tech. Monograph No. 12: Track loading fundamental by C. W. Clarke,1959. 11. Civil Engg. Report No. C-100: Dynamic augments of track loads, 1971. 12. 53rd TSC Report, 1977, Item No. 716. 13. IHHA-1997, Strategy beyond 2000. Sixth International Heavy Haul Railway Conference Cape Town, south Africa,Pg.1155-1158.

14 . STRATEGIES FOR MEETING TRANSPORT DEMAND Role of Railways

by Ashutosh Banerji for RAILWATCH

15. Technical Report No.4, on load carrying capacity of masonry arch bridges, By Sh. R.R. Jaruhar, Member Engg. Rly Board.

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INDEX

S.No.

DESCRIPTION PAGE No.

1.00 Introduction 1 1.1 General 1 1.2 Wake up Call

1

1.3

Comparative Evaluation of India Railways with advanced Railways 2

1.4

Indian Railway has to embark upon a path of modernisation and expansion in a big way, as per vision of PM.

2-3

1.4.1

Enhance Transport Capacity

3-4 4

1.4.2 Dedicated Freight Corridors

4-5

1.4.3 The benefit of high axle loads

4

2.0 Assessment of track structure

5

2.1.1 Design of Rail Section 5

2.1.1 Rail Stresses

5-6

2.1.2 Rail wheel contact stresses 6-7

2.1.3 Design of sleeper 7-9

2.1.4 Stress on ballast bed 9-10

2.1.5 Stress on formation 10-11

3.0 Implications and solutions for running 30t axle load on existing Track.

12

3.1 Implication on Rail 12

3.1.1 Increased contact stress and fatigue failures 12-14

3.1.2 Rail grinding 14-15

3.1.3 Effect of curvature and track geometry. 16-17

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3.1.4 Effect of flat wheel 17-19

3.1.5 Effect on Rail/Weld failure 19

3.2 Implication on sleeper 19

3.3 Implication on ballast and formation 20-21

3.4 Implications on SEJS and turnout 21

3.5 Implications on maintenance of track 21

3.5.1 Swedish Model study 21

3.5.2 AASHO test 21

3.5.3 Finding of AAR panel 22

3.6 Implications on Bridges 22

3.7 Implication on inspection schedule 23

3.8 USFD testing 23

4.0 Implications and solutions for running 30t axle load on new Track. 23

4.1 Up gradation of track, bridges and formation 23

4.1.1 Design of rail. 23

4.1.2 Design of sleeper 24

4.1.3 Design of ballast bed 24

4.1.4 Design of formation 24

4.1.5 Design of formation 24

5.0 Alternative strategy, wagon modification 25

5.1 Introduction of 3 axle bogie 25

5.2 Communication inputs 26

6.0 On Going projects 26

7.0 Conclusion 26-27

8.0 References 28

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