Bridge Construction Specifications

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Questions and Answers

What is the designation of the person responsible for supervising the welding process?

Helper Khalasi/Khalasi

Welder Grade I/Grade II

Process Supervisor (correct)

Trackman

What is the purpose of including bolt hole distance in the Thermit Weld Register?

To track the progress of the welding process

To ensure proper alignment of the rails (correct)

To determine the type of rail to be used

To calculate the total cost of the project

What is the primary responsibility of the Trackman?

To perform duties as per workload (correct)

To perform trimming and grinding operations

To manage the workload of the welding team

To assist the Welder Grade I/Grade II

What is the purpose of including the Agency code in the Thermit Weld Register?

To identify the agency responsible for the welding process Signup and view all the answers

What is the designation of the person responsible for performing trimming and grinding operations?

Weld Trimmer and Rail Profile Grinder Signup and view all the answers

What is the purpose of including the Portion details in the Thermit Weld Register?

To provide additional information about the rail Signup and view all the answers

What is the purpose of including the Date of manufacturing in the Thermit Weld Register?

To track the manufacturing history of the rail Signup and view all the answers

What is the purpose of including the USFD testing in the Thermit Weld Register?

To ensure the quality of the weld Signup and view all the answers

What is the recommended range of values of gaps in mm for 39m panels in Zone I and II when the rail temperature is between tm - 7.5°C to tm - 2.5°C?

7-11 Signup and view all the answers

What is the permissible value of gap in mm for 26m rolled rails in Zone III and IV when the rail temperature is between tm + 2.6°C to tm + 7.5°C?

2-7 Signup and view all the answers

What is the range of rail temperature during gap survey for which the permissible value of gap is 9-13 mm for 39m panels in Zone I and II?

tm - 12.5°C to tm - 7.6°C Signup and view all the answers

How is the average of the measured gaps worked out?

By taking the average of the measured gaps as shown in the proforma for gap survey Signup and view all the answers

What is the recommended range of values of gaps in mm for 26m rolled rails in Zone III and IV when the rail temperature is between tm + 7.6°C to tm + 12.5°C?

1-5 Signup and view all the answers

What is the rail temperature range during gap survey for which the permissible value of gap is 5-9 mm for 39m panels in Zone I and II?

tm - 2.4°C to tm + 2.5°C Signup and view all the answers

What is the permissible value of gap in mm for 39m panels in Zone III and IV when the rail temperature is between tm - 17.5°C to tm - 12.6°C?

11-14 Signup and view all the answers

What is the rail temperature range during gap survey for which the permissible value of gap is 3-7 mm for 26m rolled rails in Zone I and II?

tm + 2.6°C to tm + 7.5°C Signup and view all the answers

What is the maximum span length for a bridge with single span and sliding bearings at both ends?

30.5 metre Signup and view all the answers

How many anchoring arrangements are required for central sleepers in end spans?

Two Signup and view all the answers

What is the frequency of lubrication of sliding bearings?

Once in two years Signup and view all the answers

When should the sliding bearings be inspected and cleared of foreign materials?

During the months of March and October Signup and view all the answers

How should the girders be positioned before laying LWR/CWR?

Centrally positioned with reference to the location strips on the bearing Signup and view all the answers

What type of fastenings should be provided for the remaining sleepers?

Rail-free fastenings Signup and view all the answers

What is the purpose of anchoring arrangements for central sleepers?

To maintain the alignment of the track Signup and view all the answers

What is the standard for laying and maintaining the track structure in the approaches?

As stated in (1) (b) & (c) above Signup and view all the answers

What is the recommended number of packing rounds for newly laid track or freshly deep screened track?

Three rounds Signup and view all the answers

What type of clamps are used with joggled fishplates?

Bolted clamps Signup and view all the answers

What is the primary factor that resists thermal force in a Longitudinal Welded Rail (LWR)?

Track structure Signup and view all the answers

What is the unit of longitudinal ballast resistance of sleepers?

kg / cm / rail per sleeper Signup and view all the answers

What is the indicative density of PSC sleeper?

1660 kg / m Signup and view all the answers

What is the purpose of imposing a temporary speed restriction?

To allow for welded panels to settle Signup and view all the answers

What is a critical factor in determining the gap at SEJ?

Coefficient of linear expansion of rail steel Signup and view all the answers

What is the purpose of the initial gap at SEJ?

To accommodate thermal expansion Signup and view all the answers

What is the primary purpose of de-stressing operation of LWR?

To relieve the internal stresses in the rail Signup and view all the answers

What is the temperature range at which de-stressing operation is typically done?

At the de-stressing temperature (td) Signup and view all the answers

What is the purpose of removing impediments to free movement of rail during de-stressing operation?

To enable the rail to adjust to its original shape Signup and view all the answers

What is the recommended duration of a traffic block during de-stressing operation?

Adequate duration to allow the rail temperature to fall within the range specified for td Signup and view all the answers

Under whose supervision is the de-stressing operation of LWR done?

JE/SSE/P.Way Signup and view all the answers

What is the criterion for dividing LWR into manageable lengths for de-stressing?

Availability of Block, labour etc. Signup and view all the answers

What is the purpose of using rail tensors during de-stressing operation?

To allow de-stressing at a little lower temperature than the targeted stress-free temperature Signup and view all the answers

What is the relevance of Fig 3.19 in the context of de-stressing operation of LWR?

It illustrates the setting of gap at Improved SEJ with Single gap of max. 80mm Signup and view all the answers

Study Notes

Bridges with Rail-Free Fastenings

Bridges with rail-free fastenings and partly box-anchored are allowed with single spans not exceeding 30.5 meters and having sliding bearings at both ends.
The overall length of the bridge should not exceed the maximum provided in Table 1.
Central sleepers shall be anchored with an anchoring arrangement, and the remaining sleepers shall be provided with rail-free fastenings.
The track structure in the approaches shall be laid and maintained to the standards stated in the guidelines.

Welding Team Composition

The composition of the welding team consists of:
- Welder Grade I/Grade II: 1
- Welder Grade III/Skilled Artisan: 2
- Helper Khalasi/Khalasi: 5
- Trackman: as per workload

Thermit Weld Register

A proforma for the Thermit Weld Register is provided, which includes:
- Sl. No.
- Date of welding
- Location details
- Rail details
- Bolt hole distance (in mm)
- Portion details
- Welding details
- Agency code
- Batch number
- Manufacturing code
- Process Supervisor code
- Welder code

Recommended Range of Gaps

The recommended range of values of gaps during service for various ranges of rail temperature is provided in Table 2.
The table includes ranges for Zone I and II, as well as Zone III and IV.
The gaps are measured in mm and are dependent on the rail temperature.

Calculations for Adjustment

The average of the measured gaps is worked out as shown in the proforma for gap survey.
For newly laid tracks, three rounds of packing are required, with the last two rounds done by on-track tamping machines.

Temporary Speed Restriction

A temporary speed restriction is imposed on the length of track where welded panels are joined by 1m long fishplates with special screw clamps or joggled fishplates with slotted grooves and bolted clamps.

Gaps at SEJ

The thermal force in a Long Welded Rail (LWR) is to be resisted by suitable track structure.
The gap at SEJ depends on:
- Longitudinal Ballast Resistance of sleepers
- Area of rail section
- Modulus of Elasticity (E) for rail steel
- Coefficient of linear expansion (α) for rail steel
- Difference between the De-stressing temperature and prevailing rail temperature of LWR
- Initial gap at SEJ at de-stressing temperature

De-stressing Operation of LWR

De-stressing shall be done during a traffic block under the personal supervision of JE/SSE/P.Way.
De-stressing shall be done when the rail temperature falls between the range provided for t d.
If the required temperature cannot be obtained in the field, de-stressing can be done at a little lower temperature than the targeted stress-free temperature with the use of rail tensors.

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Description

This quiz covers the specifications and design requirements for bridges with rail-free fastenings and box-anchored bridges. It includes details on overall length, anchoring arrangements, and sleeper design.