1. INTRODUCTION OF HIGHER AXLE LOADS ON INDIAN RAILWAYS
Shiv Kumar
Director/IRICEN

2. Introduction of higher axle loads on IR
After experience of successful run of the pilot project of running of CC+8+2 trains and introduction of axle load of t on IR since May,2005 on identified iron ore routes, Hon. MR announced in his Budget Speech ,06 that 25 T axle load trains will be introduced on IR during the year
Initially ,two routes have been identified as under:
1.Dallirajahara-Bhilai
2.Banspani-Daitari

3. Indian Railways march towards heavier axle loads
Universalise t axle load on IR
Construct Dedicated Freight Corridors (DFC) fit for 32.5 t axle loads
Feeder Routes To DFC to be strengthened for running of 25 t axle load operations
Other routes identified for upgradation for 25 t axle load operation

4. Proposed Axle Load &TLD for DFC
Track Load Density (TLD):12 t/m

5. Proposed wagon dimensions
(i) Width of wagon
(a) It has been decided to reduce the height of goods platform to 840 mm for a width of 1850 mm from track centre on routes where these wagons will be running
(b) The width 3500 mm as proposed above is for door less wagons. The width for wagons with doors will be 3250 mm.
Height above rail level (in mm)
Width (in mm)
1000
3500
945
3250
<945
3135

6. Proposed wagon dimensions(contd.)
(ii)Height of wagon
For open wagons mm
For covered wagons mm at side
4385mm at centre
(iii) Wheel Diameter
Maximum 1050 mm and minimum 840 mm when new

7. Maximum Moving Dimensions (MMD)
(a) For DFC
Width = m
Height = m
(b) For feeder routes
Width = m
Height = m where double stack container will be running
= m on other routes

8. Track Structure for DFC
68 kg (90 UTS or higher) Rails
New Design of PSC sleeper, 1660/km
E-clip elastic fastening with improved rubber pads being developed by RDSO
Flash butt welded joints
Thick Web Switches and swing nose crossings in turnouts
PSC sleepers to be designed for turnouts ,level crossings , SEJs, Bridge Approaches

9. Formation,gradients ,curvature for DFC
Formation width in embankment/cutting and centre to centre spacing:
-Single Line m (as existing)
-Double Line m
- C/C spacing of DFC tracks 5.50 m
-C/C spacing of DFC from existing 6 m
Suitable thickness of sub-ballast/blanket/reinforced earth to be provided
Curvature limited to 700m (2.5 degree)
Ruling Gradient - 1 in 200 compensated

10. Proposed Loading Standards for bridges on DFC
Locomotives:
Axle Load t
Tractive Effort - 60 t per loco for double headed
- 45 t per loco for triple headed
Braking Force - 25 t per loco
Train Loads:
Axle Loads t
Track Load Density-12t/m

11. TRACK STRUCTURE FOR RUNNING 25T AXLE LOAD TRAINS
As per Railway Board’s Track Policy Circular no.2 of 2006 dtd 19th July,06,the minimum track structure for routes identified for running of 25t axle load trains, to be adopted in all future track renewals, construction of new lines, doubling etc. will be as follows:
Rail Section……..……60kg 90UTS
Sleepers and density….PSC of existing design , nos per km
Ballast cushion……….300mm
Points & crossing……Fan-shaped layout with
60kg curved switches

12. TRACK STRUCTURE FOR RUNNING 25T AXLE LOAD TRAINS (contd.)
Existing track structure consisting of 52kg 90UTS rails on PSC sleepers with 1540 nos. per km and 250mm ballast cushion may be permitted for running of 25t axle load trains at a restricted speed of 60 kmph, for BOXN and similar type of wagons.
In case of sidings, the minimum track structure for 25T axle load operation will be of 52kg 90UTS rails on PSC sleeper with 1540 nos. per km and 250mm ballast cushion for speeds upto 60 kmph. In cases where speed is not exceeding 30kmph, track structure comprising of 52kg 72UTS rails on PSC sleeper with 1540 nos. per km and 250mm ballast cushion will suffice.

13. TRACK RENEWAL FOR 25T AXLE LOAD OPERATION (contd.)
52kg 90UTS rails will be replaced only when they become due for renewal on age-cum-condition basis.
Wherever the existing sleeper density is 1540 nos per km, works for increase in sleeper density alone will not be sanctioned. These will only be done as and when sleeper replacement is required, either due to age-cum-condition basis or to suit higher rail section.

14. TRACK RENEWAL FOR 25T AXLE LOAD OPERATION (contd.)
Where track renewal is sanctioned as 52kg 90UTS rails and PSC sleepers with 1540 nos per km., the sleeper density should be increased to 1660 nos per km by Material Modification. Railways should, however, start execution with the increased sleeper density pending approval of MM estimate, to avoid the delay. It however should also be ensured that MM gets sanctioned within three months.
Rail section should immediately be modified to 60kg 90UTS rails, wherever it is feasible. For other cases, it should start within next 6 months. During this period, preparatory work such as procurement of related fittings etc. be ensured. Railway should also ensure sanction of MM estimate within three months.

15. EXAMINATION OF EXISTING BRIDGES FOR 25T AXLE LOAD (Feeder routes):
Bridges have to be checked for 25 t axle load & trailing load density of 9.33t/m.
Works already planned and awarded especially for construction of bridges/rebuilding will be as per existing loading standards( i.e. MBG)
Correction slip no 23 & 34 issued by RDSO no CBS/PSBC dtd.21/ ,CBS/PBR dtd.24/ respectively should be taken into account while checking the suitability of existing bridges
Superstructure:
RDSO has examined on following premises:
Actual axle load and axle spacing for moving loads of WAG9 locomotive and 25 T BOXN wagons.
Coefficient of Dynamic Augment (CDA) for limited speed of 60kmph .

16. RESULTS OF ANALYSIS (for superstructures of standard spans):
STANDARD SPAN(M)
SPEED POTENTIAL OF BRIDGES FOR DIFFERENT LOADING STANDARDS OF EXISTING BRIDGES
BGML LOADING
Axle load T
TLD T/M
T. Effort T
RBG LOADING Axle load T
TLD T/M
T. Effort T
MBG LOADING Axle load T
TLD T/M
T. Effort T
1-20
60kmph
20-63
60 kmph
55 kmph
78.8
50 kmph

17. Substructure:
Substructure analysis to be done case by case.
Bearings:
Bearings of standard spans designed for MBG loading are fit for 25 T axle load.
Bearings of standard spans designed for BGML/RBG loading having spans 31.9m, 47.25m, 63.0m and 78.8m (all effective spans) needs strengthening.
One time inspection of Bearings apart from schedule inspection to be done by Zonal Railways for running of 25 T axle load.
RDSO has issued correction slip to standard code of design for sub-structures and foundation regarding checking of sub-structures and foundation of bridges, in March 06, for all Zonal Railways, in which instructions for taking tractive effort, passive pressure of soil, tilt and shift of well foundation, hydro dynamic forces etc. have been revised.

18. Bridge Inspection and Monitoring
Following locations/members to be monitored as being critical from fatigue consideration.
Connection of cross girder with stringer.
Outstanding leg of the top compression flange of the stringer at its junction with web rivet.
Rivets connecting bottom flange angle of the stringer with web at mid span.
Vertical members at connection with top chords.
Rivets connecting bottom flange of cross girders with web at mid span.
Rivets of splice joints of bottom flange in plate girders.
Physical condition of bridges to be certified by Zonal Railways.
More intensive Bearing & Substructures Inspection to be done ( will need more man power)
Directions for checking superstructure of non standard spans including Arch Bridges etc., bearing of non standard spans and substructure of all bridges issued to Zonal Railways.

19. Conclusions
Experience of increased axle load on other major railway systems in world has shown that Fatigue life of rail comes down drastically with increase in axle loads and it may take 5 to 10 years for heavy axle loads to tell its effect on rails.
Rail grinding is required to be undertaken to prevent Rolling Contact Fatigue and increase rail life.
The rail life obtainable under present axle load itself is in range of GMT which is way below the prescribed life of 800 GMT for 90 UTS rails.
Till rail grinding is implemented, there is a need to safe guard against rail fractures due to RCF by extensive and effective USFD.
Fatigue life of rails also needs a review. Life of rails subjected to heavier axle load needs to be realistically brought down till grinding is introduced.

20. Conclusions
Installation of way-side vehicle condition monitoring systems for identifying poorly performing wagons will go a long way in reducing stress state of track by identifying defective rolling stock and removing them from service.
These are:
Wheel Impact Load Detector (WILD),
Truck Performance Detector (TPD),
Hot Bearing Detector (HBD),
Dragging Equipment Detector (DED),
Hot Wheel Detector (HWD),
Truck Hunting Detector (THD),
Wheel Profile Monitoring System etc
Development of track friendly bogie, self steering is required.
Review after one more year of operation of 22.82t axle load may help to firm up the position.