Girder Launching for Bridges: Complete Methodology, Safety, Alignment, QA/QC and Field Guide

GIRDER LAUNCHING FOR BRIDGES

Safe Launch • Precise Alignment • Stronger Connection

A well-planned girder launching operation is not merely a lifting activity. It is a carefully engineered temporary structural system involving the girder, launching equipment, bearings, piers, abutments, temporary supports, hydraulic systems, winches, wire ropes, access arrangements and, most importantly, people.

ENGINEERING & SAFETY WARNING

Girder launching is a critical bridge-construction activity. The actual launching operation shall be carried out only in accordance with the approved structural design, erection scheme, method statement, temporary works design, lifting plan, manufacturer's instructions and project-specific safety requirements.

This article is a technical field guide and shall not be treated as a substitute for project-specific engineering calculations, approved drawings or competent supervision.

1. Introduction

Girder launching is one of the most critical stages in bridge construction. Whether the superstructure consists of precast prestressed concrete girders, steel girders, PSC I-girders, box girders or other prefabricated elements, the erection process temporarily places the structural members in configurations that may be substantially different from the final completed bridge.

During launching, the girder may pass through several critical positions: transport position, lifting position, suspended position, partially supported position, cantilever condition and final bearing-supported condition. Every one of these stages produces a different load path and a different structural response.

A common field mistake is to consider only the final position of the girder. An experienced bridge engineer considers the entire erection sequence. The most critical condition may occur during launching and not after the girder has reached its final position.

Engineering Principle:

A bridge is designed for its final configuration, but it must also be engineered for every temporary configuration created during construction.

2. Why Girder Launching Requires Special Attention

Girder launching combines structural engineering, lifting engineering, temporary works, hydraulics, mechanical systems, surveying, communication and site safety.

A small error in one system can affect the entire operation. For example, incorrect bearing elevation can create unintended differential reactions; unequal hydraulic lifting can twist a girder; inadequate temporary support can overload a pier; excessive wind can cause lateral instability; and poor communication can result in simultaneous contradictory commands.

Typical Risks

• Girder instability during lifting.
• Excessive lateral movement.
• Temporary support failure.
• Launching-girder structural failure.
• Hydraulic jack malfunction or uneven lifting.
• Wire-rope failure or improper anchorage.
• Unintended girder rotation.
• Girder collision with pier, bearing or launching equipment.
• Overloading of partially completed bridge components.
• Wind-induced movement.
• Incorrect bearing position or level.
• Communication failure between operators.
• Personnel entering the suspended-load exclusion zone.

3. Applicable Indian Codes and Technical References

The following standards and documents are particularly relevant to bridge girder erection and launching. The latest project-adopted editions, amendments, errata and contractual requirements shall always be checked before execution.

Reference	Subject / Application
IRC:6	Loads and load combinations for road bridges, including construction and erection-related effects.
IRC:112	Concrete road bridges and construction-stage design considerations. Construction equipment loads, launching gantry effects, dynamic effects, longitudinal forces, unbalanced construction effects and wind effects are important considerations.
IRC:78 Part 1:2024	Foundations and substructure, including requirements relevant to supports, foundations and substructure stability.
IRC:83 Series	Bridge bearings including elastomeric, POT, pin, metallic guide and sliding bearing systems, as applicable.
IRC:5	General features of design of road bridges and associated structural considerations.
IRC:24	Steel road bridges where steel girders or steel components form part of the bridge superstructure.
IS 800	General construction in steel, applicable to structural steel components, temporary steel works and associated design checks where applicable.
IS 456	Plain and reinforced concrete construction. It is relevant to concrete components and supports where applicable.
Manufacturer's Manual	Mandatory equipment-specific limitations, hydraulic capacities, permissible loads, operating procedures, inspection requirements and emergency procedures.

Important:

IRC publications are not a substitute for the approved erection design. Launching equipment and temporary works must be specifically checked for the actual span arrangement, girder weight, support geometry, launching sequence, wind condition and equipment configuration.

4. Basic Philosophy of Girder Launching

The objective of launching is to transfer the girder from its initial location to its final bearing-supported position without exceeding the permissible stress, deflection, stability and reaction limits of any component involved in the operation.

The load path must be understood at every stage.

1

Planning

Study drawings, survey information, erection scheme and method statement.

2

Equipment

Inspect launching girder, winches, jacks, ropes, cranes and accessories.

3

Site Preparation

Verify pier, abutment, launching path, working platforms and access.

4

Trial Run

Conduct controlled dry run and system checks.

5

Launching

Move the girder slowly under continuous supervision.

6

Placement

Lower the girder onto the bearings and establish correct seating.

7

Final Inspection

Verify alignment, level, bearing condition and connections.

5. Pre-Launching Engineering Review

Before bringing the launching equipment to site, the complete erection philosophy should be reviewed.

5.1 Study Structural Drawings

• Span arrangement.
• Girder type and dimensions.
• Girder self-weight.
• Centre of gravity.
• Lifting points.
• Diaphragm arrangement.
• Bearing type and dimensions.
• Pier cap dimensions.
• Construction joints.
• Temporary support requirements.

5.2 Review Construction Sequence

The erection sequence should be clearly defined. It should identify where the girder will be lifted, supported, transferred, launched, rotated, lowered and finally seated.

The engineer should ask one fundamental question:

"At every stage of launching, where is the load going?"

If this question cannot be answered quantitatively, the launching operation should not proceed.

6. Method Statement

A proper method statement should contain, at minimum:

• Scope of work.
• Bridge and span details.
• Girder identification and weight.
• Launching equipment details.
• Equipment capacity.
• Temporary works design.
• Lifting arrangement.
• Launching sequence.
• Hydraulic jacking sequence.
• Winch arrangement.
• Wire-rope arrangement.
• Survey and alignment procedure.
• Bearing installation procedure.
• Communication protocol.
• Weather limitations.
• Wind-speed limitation specified by the approved erection design/equipment manufacturer.
• Emergency stop procedure.
• Rescue arrangement.
• Traffic management where required.
• Inspection and testing requirements.
• Quality-control hold points.
• Documentation and reporting procedure.

7. Launching Girder / Launching Gantry Inspection

The launching girder is itself a temporary structure. It must therefore be treated with the same engineering discipline applied to permanent structural works.

Inspection Checklist

• Main girder members.
• Cross girders.
• Bolted connections.
• Welded connections.
• Pin connections.
• Launching wheels.
• Hydraulic cylinders.
• Hydraulic hoses.
• Hydraulic power pack.
• Winches.
• Wire ropes.
• Sheaves and pulleys.
• Anchorage points.
• Safety locking devices.
• Electrical system.
• Limit switches.
• Emergency stop system.
• Load indicators.
• Level indicators.
• Communication equipment.

Never accept equipment capacity from appearance.

The equipment's rated capacity must be supported by appropriate documentation and must correspond to the actual configuration and operating condition.

8. Crane and Lifting Equipment

Where cranes are used for girder lifting or launching support, the lifting plan must consider the actual radius, boom configuration, ground bearing condition, counterweight, outrigger arrangement, lifting accessories and environmental conditions.

The crane's nominal rated capacity alone is not sufficient.

A crane capable of lifting 100 tonnes at a short radius may have a substantially lower permissible capacity at a larger radius.

Before Lifting

• Verify crane configuration.
• Verify load weight.
• Verify lifting radius.
• Verify ground bearing capacity.
• Check outrigger arrangement.
• Check lifting accessories.
• Check hook and safety latch.
• Check sling certification.
• Establish exclusion zone.

9. Site Preparation

The supporting structure must be ready before launching equipment is mobilized into the erection zone.

Check the Following

• Pier cap concrete strength and acceptance.
• Pier cap dimensions.
• Bearing pedestal dimensions.
• Bearing seat levels.
• Centre lines.
• Longitudinal axis.
• Transverse axis.
• Launching path.
• Working platform.
• Temporary supports.
• Access for personnel.
• Access for emergency vehicles.
• Electrical supply.
• Lighting for approved night work, if applicable.

10. Survey and Alignment Control

Survey control is one of the most important components of successful girder launching.

A small positioning error at the pier can become a significant cumulative alignment error over several spans.

Establish Permanent Control Points

• Bridge centre line.
• Pier centre line.
• Bearing centre line.
• Girder reference line.
• Reference benchmarks.
• Top-of-pier levels.
• Bearing seat levels.

Total station, precise levelling and other appropriate survey instruments should be used according to project requirements.

Field Tip:

Do not depend on one survey reading immediately before launching. Establish independent reference points so that the position can be verified again after the girder is placed.

11. Bearing Installation and Inspection

The bearing is the interface through which the superstructure transfers reaction to the substructure. Incorrect bearing installation can create eccentric or unintended reactions.

Before Girder Placement

• Confirm bearing type.
• Confirm bearing identification.
• Check orientation.
• Check top and bottom plate condition.
• Check bearing centre lines.
• Check pedestal level.
• Check bearing seat cleanliness.
• Remove loose debris.
• Verify approved installation procedure.

For bearings requiring specific installation materials, lubrication or sliding surfaces, only the material and procedure specified by the approved bearing design/manufacturer should be used.

Important:

Never apply an arbitrary lubricant to a bridge bearing merely because the bearing appears to require lubrication. Different bearing systems have different interfaces and installation requirements.

12. Girder Lifting

Lifting points should be located as specified in the approved lifting design. Improvised lifting points are unacceptable.

The lifting arrangement should consider:

• Girder self-weight.
• Centre of gravity.
• Lifting-point spacing.
• Sling angle.
• Lifting accessory capacity.
• Local stresses at lifting points.
• Girder stability.
• Temporary bracing.
• Potential torsion.

Sling Angle

As the sling angle becomes flatter, the tension in the sling increases. Therefore, sling geometry must be checked rather than relying on nominal capacity.

For a simplified symmetric two-leg arrangement: T ≈ W / (2 sin θ) where: W = lifted load T = tension in each sling leg θ = angle of sling measured from the horizontal

The actual lifting arrangement must be checked by a competent lifting engineer because real systems may involve unequal load sharing, multiple lifting points, spreader beams, eccentricity and dynamic effects.

13. Trial Run

A trial run is one of the most valuable safety measures in girder launching. It provides an opportunity to identify mechanical, hydraulic, electrical, survey and communication problems before the actual girder movement.

Trial Run Should Verify

• Launching direction.
• Hydraulic operation.
• Winch operation.
• Brake operation.
• Communication system.
• Emergency stop.
• Limit switches.
• Travel path.
• Clearance.
• Temporary supports.
• Load monitoring.
• Operator visibility.

Expert Tip:

The trial run should be treated as a rehearsal of the actual operation, not as a ceremonial movement of the equipment.

14. Actual Girder Launching

The actual launching should be slow, controlled and uninterrupted.

Only designated personnel should issue operational commands.

Typical Sequence

1. Confirm pre-launch clearance.
2. Confirm weather and wind condition.
3. Confirm all personnel are outside the exclusion zone.
4. Confirm communication between operator, signalman and engineer.
5. Lift or transfer the girder into launching position.
6. Check initial stability.
7. Begin controlled movement.
8. Stop at predefined inspection points.
9. Check alignment and support reactions where instrumentation is provided.
10. Continue movement under controlled speed.
11. Bring the girder to the final position.
12. Lower onto the bearings in the approved sequence.
13. Release temporary supports only after stability is confirmed.

15. Hydraulic Jacking

Hydraulic jacking is a particularly sensitive operation because an apparently small difference in stroke or pressure between jacks can produce rotation or torsion.

Monitor

• Hydraulic pressure.
• Jack stroke.
• Relative elevation.
• Girder tilt.
• Support reactions where instrumentation is available.
• Oil leakage.
• Hydraulic hose condition.

Do not assume equal hydraulic pressure means equal load.

Actual reaction depends on hydraulic-system characteristics, jack area, friction, load distribution, geometry and the structural system. Pressure readings should therefore be interpreted within the approved jacking procedure.

16. Wind and Weather Considerations

Wind is one of the most underestimated risks during girder erection.

A long girder can behave like a large sail. Even if the girder is within the lifting capacity of the equipment, lateral wind load can create dangerous movement and torsional effects.

Weather Checks

• Wind speed.
• Wind gusts.
• Rain.
• Lightning.
• Visibility.
• Wet and slippery surfaces.
• Flooding.
• Storm warnings.

The permissible wind speed for lifting or launching must be established from the approved erection design, equipment manufacturer's instructions and project safety plan. A generic wind-speed number should not be adopted for all launching operations.

17. Communication Protocol

Communication failure during launching can become an immediate safety hazard.

A single person should normally be designated as the authorized launching commander/signalman according to the approved lifting plan.

Typical Commands

• START
• STOP
• EMERGENCY STOP
• FORWARD
• BACK
• RAISE
• LOWER
• LEFT
• RIGHT
• HOLD

Golden Rule:

ANY PERSON WHO OBSERVES AN IMMEDIATE DANGER SHOULD HAVE THE AUTHORITY TO CALL "STOP".

18. Exclusion Zone

No unauthorized person should remain below or adjacent to a suspended or actively moving girder.

The exclusion zone should account for:

• Potential girder swing.
• Potential girder rotation.
• Falling-object risk.
• Equipment movement.
• Wire-rope failure trajectory.
• Hydraulic equipment movement.
• Emergency access.

19. Final Placement on Bearings

The final lowering operation requires particular attention because the girder is transitioning from temporary support to permanent structural support.

Check Before Final Seating

• Bearing position.
• Bearing orientation.
• Bearing level.
• Girder centre line.
• Longitudinal position.
• Transverse position.
• End clearances.
• Seating condition.
• Temporary supports.

The girder should not be considered successfully launched merely because it has reached the approximate location. It is successfully placed only after the specified position, seating, alignment and bearing conditions have been verified.

20. Alignment and Level Checks After Launching

After placement, conduct an independent survey.

Parameter	Check
Longitudinal Position	Compare with approved setting-out coordinates.
Transverse Position	Check against girder reference line and bridge centre line.
Top Level	Compare with approved profile/elevation.
Cross Fall	Verify where applicable.
Bearing Position	Check centre and orientation.
Girder Spacing	Verify against approved arrangement.
Diaphragm Location	Check relative position and clearances.

21. Quality Assurance and Quality Control

Pre-Launching QA/QC

• Approved drawings available.
• Approved method statement available.
• Approved launching arrangement available.
• Equipment certificates verified.
• Girder inspection completed.
• Bearing inspection completed.
• Survey points verified.
• Temporary works inspected.

During Launching

• Movement monitored.
• Hydraulic readings recorded.
• Unexpected deformation monitored.
• Communication maintained.
• Wind condition monitored.
• Temporary supports checked.

Post-Launching

• Final survey.
• Bearing inspection.
• Girder inspection.
• Damage inspection.
• Alignment verification.
• Photographic record.
• Launching log.
• Engineer approval.

22. Real-Life Field Example 1 — Incorrect Bearing Level

Consider a bridge where the bearing pedestal on one side is approximately 8–10 mm higher than the intended level.

If the issue is ignored during girder placement, the girder may initially appear to be correctly seated. However, the unintended differential level can cause rotation, uneven bearing contact and redistribution of reactions.

The field lesson is simple:

Survey the bearing seats before the launching operation, not after the problem has already occurred.

23. Real-Life Field Example 2 — Wind During Girder Erection

A long precast girder can have a very large exposed surface. During lifting, the girder is particularly vulnerable because its normal stabilizing supports are absent.

A sudden gust can rotate the girder and cause it to strike a pier, launching gantry or nearby girder.

The correct engineering response is not to ask, "Can the crane lift the girder?" The correct question is:

"Is the complete lifting system stable under the expected environmental condition?"

24. Real-Life Field Example 3 — Unequal Hydraulic Lifting

Suppose two hydraulic jacks are used to raise a girder. If one jack advances faster than the other, even by a relatively small amount, the girder may rotate about its longitudinal axis.

Such rotation can introduce torsional effects and cause the girder to move unexpectedly relative to the launching equipment.

Therefore, jacking should be performed according to a predetermined sequence with continuous monitoring.

25. Real-Life Field Example 4 — Poor Communication

During complex launching operations, several teams may work simultaneously: crane operators, hydraulic operators, riggers, surveyors, safety personnel and engineers.

If one operator receives a command to move while another person believes the system is on hold, an unsafe condition can develop within seconds.

Therefore, communication is not an administrative formality. It is part of the temporary structural safety system.

26. Expert Field Tips

1. Survey twice, launch once. Verify critical coordinates independently before launching.
2. Never rely only on visual alignment. A girder may look straight and still be outside tolerance.
3. Mark the centre lines clearly. Paint or physically mark reference lines on pier caps, bearings and girders.
4. Keep the launching path clean. Even a small obstruction can create a sudden shock load.
5. Control speed. Slow movement provides more time to identify abnormal behaviour.
6. Stop after every major transition. Inspect when the load path changes.
7. Watch the structure, not only the machine. Unexpected movement of the pier cap, bearing, girder or temporary support may be the first indication of a problem.
8. Do not normalize abnormal readings. An unexpected hydraulic pressure, displacement or tilt should be investigated.
9. Keep emergency access clear. The site must remain accessible throughout the operation.
10. Document the first successful launch. It provides valuable information for subsequent spans.

27. DOs — Girder Launching

• DO prepare an approved method statement.
• DO conduct a detailed risk assessment.
• DO verify girder weight and centre of gravity.
• DO inspect the launching girder before use.
• DO verify equipment capacity for the actual configuration.
• DO inspect wire ropes, slings, shackles and lifting accessories.
• DO verify bearing position and level.
• DO establish independent survey control.
• DO conduct a trial run.
• DO monitor wind and weather.
• DO maintain continuous communication.
• DO establish a controlled exclusion zone.
• DO use tag lines where appropriate and safe.
• DO monitor hydraulic pressure and stroke where applicable.
• DO stop immediately when an unsafe condition develops.
• DO conduct a post-launch survey.
• DO maintain photographic and written records.

28. DON'Ts — Girder Launching

• DON'T launch without approved erection methodology.
• DON'T exceed equipment manufacturer's capacity.
• DON'T use damaged lifting accessories.
• DON'T stand below a suspended girder.
• DON'T allow unauthorized personnel inside the exclusion zone.
• DON'T continue launching during unsafe weather.
• DON'T ignore abnormal hydraulic pressure.
• DON'T use improvised lifting points.
• DON'T assume equal hydraulic pressure means equal reaction.
• DON'T modify temporary works without engineering approval.
• DON'T remove temporary supports before the approved sequence permits it.
• DON'T force a girder into position by uncontrolled pushing or pulling.
• DON'T depend solely on verbal communication in a noisy launching area.
• DON'T accept approximate bearing alignment when precise setting-out is required.

29. Emergency Stop Conditions

The operation should be stopped immediately if any of the following conditions develop:

• Unexpected girder movement.
• Unexpected structural deformation.
• Hydraulic leakage or failure.
• Wire-rope damage.
• Equipment malfunction.
• Unexpected bearing movement.
• Loss of communication.
• Sudden wind increase beyond approved limits.
• Lightning or severe weather.
• Unauthorized person entering the exclusion zone.
• Unexpected obstruction.
• Abnormal noise from structural or mechanical components.
• Loss of power affecting critical equipment.

30. Emergency and Rescue Plan

An emergency plan must be prepared before launching begins.

It should identify:

• Emergency contact numbers.
• Nearest medical facility.
• Ambulance access route.
• Emergency assembly area.
• Rescue equipment.
• Fire extinguishers.
• First-aid facility.
• Electrical isolation procedure.
• Hydraulic emergency shutdown.
• Crane emergency procedure.
• Communication hierarchy.

31. Launching Record / Documentation

Every launched girder should have a traceable record.

Record	Recommended Information
Girder ID	Girder number, span and location
Date & Time	Start and completion time
Weather	Wind, rainfall and visibility
Equipment	Launching girder / crane identification
Inspection	Pre-launch checklist
Survey	Pre- and post-launch coordinates/levels
Hydraulic Data	Pressure/stroke records where applicable
Issues	Any abnormality or corrective action
Photographs	Pre-launch, launching and final position
Approval	Responsible engineer / authorized personnel

32. Recommended Pre-Launch Checklist

• ☐ Approved structural drawings available
• ☐ Approved erection scheme available
• ☐ Approved method statement available
• ☐ Risk assessment completed
• ☐ Launching equipment inspected
• ☐ Equipment certificates verified
• ☐ Lifting accessories inspected
• ☐ Girder inspected
• ☐ Girder identification verified
• ☐ Bearing installation verified
• ☐ Pier cap level verified
• ☐ Survey control verified
• ☐ Launching path cleared
• ☐ Temporary supports inspected
• ☐ Hydraulic system checked
• ☐ Winch system checked
• ☐ Communication system tested
• ☐ Emergency stop tested
• ☐ Weather checked
• ☐ Wind condition within approved limit
• ☐ Exclusion zone established
• ☐ Rescue arrangement available
• ☐ First-aid facility available
• ☐ Trial run completed
• ☐ Responsible engineer has given clearance

33. Construction-Stage Engineering — The Most Important Concept

Experienced bridge engineers understand that construction-stage design is not an optional exercise.

During erection, the bridge may temporarily experience:

• Different support conditions.
• Temporary cantilever action.
• Unbalanced loading.
• Launching equipment loads.
• Horizontal forces.
• Dynamic effects.
• Wind effects.
• Temporary reactions.
• Construction loads.
• Local stresses at lifting and support points.

Therefore, the erection sequence should be considered as an engineering load case rather than merely a construction activity.

Professional Bridge-Engineering Principle:

"The structure must be safe not only when it is complete, but also during every temporary stage through which it passes to become complete."

34. Final Acceptance After Launching

The girder should be formally accepted only after completion of the required inspection and survey checks.

Final Inspection

• Girder location verified.
• Longitudinal alignment verified.
• Transverse alignment verified.
• Level verified.
• Bearing seating verified.
• No visible damage observed.
• Temporary supports removed only as approved.
• Connections completed as required.
• Girder spacing verified.
• Diaphragm requirements verified.
• Survey records completed.
• Photographs taken.
• Inspection report signed.

35. Quality, Safety and Time — The Three-Way Balance

Construction teams are often under pressure to accelerate bridge construction. However, speed should never be achieved by removing engineering controls.

The correct objective is not simply:

"Launch the girder quickly."

The correct objective is:

Launch the girder safely, place it precisely, verify the structure and document the operation.

36. Golden Rules of Girder Launching

1. Plan before you lift.
2. Check the equipment before you operate.
3. Know the load path at every stage.
4. Never compromise temporary works.
5. Survey before and after launching.
6. Control wind and weather.
7. Keep people away from suspended loads.
8. Use one clear communication system.
9. Stop when conditions become unsafe.
10. Document everything.

37. Conclusion

Girder launching is a highly coordinated engineering operation in which structural behaviour, temporary works, mechanical equipment, hydraulics, surveying and human coordination must work together.

The strongest bridge is not created only by good concrete, reinforcement and steel. It is created by good engineering decisions at every stage of its construction.

A perfectly designed girder can still be damaged by improper lifting. A correctly designed bearing can still perform poorly if it is incorrectly positioned. A powerful launching girder can still become unsafe if the temporary support arrangement is inadequate.

Therefore, the fundamental philosophy should always remain:

PLAN WELL → CHECK EVERYTHING → LAUNCH SLOWLY → ALIGN PRECISELY → INSPECT THOROUGHLY → DOCUMENT COMPLETELY

The objective is not merely to complete one launching operation. The objective is to establish a repeatable, controlled and safe system that can be used for every subsequent span with continuous learning and improvement.

STRONG GIRDER • PRECISE LAUNCH • SAFE BRIDGE

Quality Work Today — Strong Bridge Tomorrow

38. Quick Reference — One-Page Field Philosophy

Stage	Primary Question
Planning	Is the erection sequence structurally and operationally feasible?
Equipment	Can every component safely handle the actual configuration and load?
Site	Are the supports, access, path and working platforms ready?
Survey	Are all centre lines and levels independently verified?
Trial Run	Does the complete system operate as intended?
Launching	Is the movement slow, controlled and continuously monitored?
Placement	Is the girder correctly seated on the intended bearings?
Final Check	Is the actual position within the approved tolerances?
Documentation	Can the entire operation be reconstructed from the records?

Note: This article is intended for education and field reference. Project-specific drawings, approved temporary works calculations, erection methodology, equipment manufacturer's instructions, applicable IRC/BIS provisions, contract specifications and instructions of the competent bridge engineer shall govern actual construction.

Prepared as a bridge-construction field guide.