Monday, April 2, 2018

SURVEYING

General purpose of Surveying –The main object of surveying is the preparation of  maps or plans which are the basis in planning and design of engineering project such as route location of railway line, roads and water supply scheme. To locate correct position of any point in horizontal and vertical plane. 

Definition of Survey : Operation of making such measurements that the relative
position of various features, natural or Artificial on the surface of the earth can be exhibited in their correct Horizontal and vertical relationship.

SURVEYING - Normally determining position in Horizontal plane is called surveying. Art of making measurement and determining the position of point in horizontal plane. Surveying is done by various instruments such as surveyor’s chain, compass, measuring tape, ranging rods, pegs etc.

LEVELLING - The art of determining relative altitudes of points on the surface of the earth or beneath the surface of earth is called LEVELLING. Determining the position of point in vertical plane. Determining relative heights or depth is called levelling.

For execution of Engineering Projects it is very necessary to determine elevations of different points along the alignment of proposed project.Other applications are :

i) Taking rail levels existing before track renewals to finalise final rail level profile including vertical curves.
ii) Initial ground levels for earthwork calculations.
iii) Levels for measurement of earthwork.
iv) Measurement of ballast etc.

DOs and Don’ts OF LWR FOR PWM, MATES & KEYMAN

DOs

1. Check and carry LWR/CWR equipment daily. Each Gang mate/ PWM should keep two Sets of joggled fishplates, 2 clamps, one rail thermometer, special 1m long fish-plates, rail closure pieces, one straight edge and one feeler gauge. The thermometer should be regularly checked with that of standard thermometer kept
in PWI's office.

2. Know the td of your section/panels.

3. Keep the ballast section full and in compacted condition particularly in cribs and shoulders. Deficiency in ballast shall be brought to the notice of PWI.

4. Keep close watch on pedestrian and cattle crossings, where the ballast is always disturbed. Make up ballast deficiency promptly.

5. Get your SEJs oiled and greased once in a fortnight.

6. Check the gaps of SEJ at extremes of temperatures.

7. Train men in detecting buckling, rail fractures etc. and protection of the trains in such cases.

Maintenance of LWR / CWR

1. Regular track maintenance in LWR/CWR includes following operations: (ACS
No. 2 of 1999)

i) Tamping/packing
ii) Lifting iii) Aligning including minor realignment of curves
iv) Shallow screening/shoulder cleaning
v) Renewal of fastening requiring lifting vi) Maintenance of buffer rails 

2. SPECIAL TRACK MAINTENANCE (ACS No. 4 of 1999)

Special track maintenance in LWR/CWR includes following operations:
i) Through fittings renewal 
ii) Deep screening/mechanised cleaning of ballast
iii) Lowering / Lifting of track iv) Major realignment of curves
v) Sleeper renewal, other than casual renewals
vi) Rehabilitation of bridges and formation causing disturbance to track

DESTRESSING DURING MAINTENANCE

Abnormal behavior of LWR/CWR whenever gets manifested in one or more of the Following, destressing shall be undertaken as per procedure laid down.

i) When the gap observed at SEJ
(a) differs beyond limits specified by ±10 mm ;
(b) exceeds the maximum designed gap of SEJ;
(c) When corner of stock/ tip of tongue rail crosses the reference line (CS.No 10).

ii) After special maintenance operations mentioned.
iii) After restoration of track following an unusual occurrence mentioned.
iv) If number of locations where temporary repairs have been done exceed three per km.

Destressing of CWR shall be done by cutting it into LWRs of about 1 km length,
which shall be joined after destressing in accordance.

Procedure for repairs

If any fracture takes place on LWR/CWR, immediate action shall be taken by the
official who detected the fracture to suspend the traffic and to protect the line. He
shall report the fracture to the Gangmate Keyman/PWI, who shall arrange for making emergency repairs to pass the traffic immediately. Repairs shall be carried out in four stages as described below

1. Emergency repairs to pass the traffic immediately: - If the gap at fracture does
not exceed 30 mm, insertion of any closure rail niece is not necessary. The traffic
may then be resumed at a speed of stop dead and 10 kmph for the first train and
20 km/h for subsequent trains.

2. Temporary repairs :- If a welding party is not readily available, the fracture shall be repaired by using a cut-rail (not less than 4 metre long) and clamped/bolted.

3. Permanent repairs: - Is carried out using wide gap welding using rail tensor or
by replacing fractured rail by a sound USFD tested rail closure (not less than 4m)
and welding the gap using rail tensor as the situation permit.

4. Destressing:- After welding of joints, a length of track equal to breathing length or about 125 meters on either side be unfastened and tapped to ensure equalization of stress and then refastened.

Repairs to Buckled Track:-

i) When the track actually buckles, the traffic shall be suspended and the cause of
buckling ascertained. The position of tongue and stock rails of the SEJ shall be checked. The methods for rectification are explained below.

ii) The rectification shall normally be carried out in the following stages under the supervision of PWI: -

1. Emergency repairs.
2. Permanent repairs. 
3. Destressing.

Deep screening / mechanized cleaning of ballast

i) Provisions laid down will also apply mutatis - mutandis to LWR/CWR with further provisions as mentioned. Wherever mechanized cleaning of ballast is resorted, the detailed procedure laid down for manual deep screening shall stand replaced by the sequence of operations of Ballast Cleaning Machine (BCM).

ii) Ballast Cleaning Machine (BCM), tamping machine and Dynamic Track Stabilizer (DTS) shall, as far as possible, be deployed in one consist.

iii) Temperature records of the sections where deep screening is to be undertaken, shall be studied for the previous and the current year. The maximum and minimum rail temperature attainable during the period of deep screening and
during the period of consolidation shall be estimated. Any of the following three methods may be adopted for Carrying out the work of deep screening/mechanised cleaning:

a) If range of rail temperature falls within td + 10ᴼ C to td + 20ᴼ C. Deep screening may be done without cutting or temporary destressing.

b) If range of rail temperature falls outside (a) above, Temporary destressing shall be carried out 10ᴼ C below the maximum rail temperature likely to be attained during the period of work. CWR shall be cut into LWRs of about 1 km length with two temporary buffer rails of 6.5 metre long clamped as per arrangements shown.

c) Wherever rail renewals are being carried out, LWR/CWR may be converted into three rail panels and deep screening done.

iv) Constant monitoring of rail temperature shall be done during the progress of work. Should the temperature rise more than 10ᴼ C above td /temporary destressing temperature, adequate precautions shall be taken including another  round of temporary destressing.

Note: Deep screening shall be under taken within 15 days of temporary destressing failing which temporary destressing may become due again, if the range of rail temperature varies appreciably.

v) During the period of deep screening, if there is any possibility of minimum temperature falling 30ᴼ C below td/temporary destressing temperature, cold weather patrol should be should be introduced to detect/ guard against rail
fractures.

vi) Sequence of operation: -

a) Deep screening of LWR may be done from one end of LWR to other end.

b) After deep screening and consolidation of track, destressing of LWR shall be
undertaken.




Note: Hot end Cold Weather Patrolmen should be aware of their duties and should be drawn, as far as Possible, from gangs.

Sunday, April 1, 2018

Destressing of LWR

1. Manually. 2.Using Rail Tensor

Manually

1. A traffic block of adequate duration should be arranged at such d time that the rail temperature will be within the temperature range specified for td during the fastening down operations. The entire work shall be done under personal supervision of the PWI.

2. Before the block is actually taken, a speed restriction of 30 km/h should be imposed and fastenings on alternate sleepers loosened. 

3. When the block is taken, the closure rails shall be removed, the SEJs adjusted and fastened.

4. The remaining, sleepers, fastenings on both running rails shall be loosened/removed starting from the ends near the SEJs and proceeding towards the centre of LWR. The rail shall be lifted and placed on rollers at every 15th - sleeper to permit the rails to move freely. While destressing on curved track, side rollers are provided. The rails shall be struck horizontally with heavy wooden mallets to assist in their longitudinal movement.