Investigation of the Suitability of Pre-cast/Pre- Fabricated Modular ...research4cap.org/...TRL-2020-SuitabilityModularBridgesRuralRoadsN… · bridges, which are slow to construct

Investigation of the Suitability of Pre-cast/Pre-

Fabricated Modular Bridges for Rural Roads in

Nepal – Pilot Study

Fabrication Report: Baugi Bridge, Parsa

Milan Kominek

Robin Workman

TRL

NEP2088A

December 2019

ReCAP | Nepal Modular Bridge Fabrication Report ii

Preferred citation: Kominek, M., Workman, R., TRL (2019). Investigation of the Suitability of Pre-cast/Pre-Fabricated Modular Bridges for Rural Roads in Nepal – Pilot Study , Fabrication of the Baugi River Modular Bridge, NEP2088A. London: ReCAP for DFID.

For further information, please contact: Robin Workman, [email protected]

ReCAP Project Management Unit Cardno Emerging Market (UK) Ltd Level 5, Clarendon Business Centre 42 Upper Berkeley Street, Marylebone London W1H 5PW United Kingdom

The views in this document are those of the authors and they do not necessarily reflect the views of the Research for Community Access Partnership (ReCAP) or Cardno Emerging Markets (UK) Ltd for whom the document was prepared

Cover photo: Milan Kominek, AF-CityPlan

Quality assurance and review table

Version Author(s) Reviewer(s) Date

1.0 Milan Kominek, Robin Workman Greg Morosiuk(TRL) M. Abedin (ReCAP PMU) N. Leta (ReCAP PMU)

20/12/2019 26/01/2020 30/01/2020

1.1 Milan Kominek, Robin Workman M. Abedin (ReCAP PMU) 11/02/2020

ReCAP Database Details : Investigation of the Suitability of Pre-cast/Pre-Fabricated Modular Bridges for Rural Roads in Nepal – Pilot Study

Reference No: NEP2088A Location Nepal

Source of Proposal TRL Procurement Method Competitive Bid

Theme Infrastructure Sub-Theme Bridges

Lead Implementation Organisation

DoLI Partner Organisation

LRBP

Total Approved Budget UK £ 299,566.98 Total Used Budget UK £ 111,286.91

Start Date 1/11/2016 End Date 30/5/2020

Report Due Date N/A Date Received 20/12/2019

ReCAP | Nepal Modular Bridge Fabrication Report iii

Contents

Abstract ...................................................................................................................................................................... iv

Key words ................................................................................................................................................................... iv

Acronyms .................................................................................................................................................................... v

Executive Summary .................................................................................................................................................... vi

1 Background ........................................................................................................................................................ 7

2 Introduction ....................................................................................................................................................... 7

3 Site Visits............................................................................................................................................................ 8

3.1 May 2019 Visit ....................................................................................................................................................... 8

3.2 November 2019 Visit to Bridge 1 ........................................................................................................................... 9

4 Summary ...........................................................................................................................................................10

4.1 Issues Identified ................................................................................................................................................... 10

4.2 Present Status ...................................................................................................................................................... 11

4.3 Next Steps ............................................................................................................................................................ 11

Annex 1 Meetings held on 27 & 28 May 2019 .....................................................................................................12

Annex 2 Selection and use of Form Release Agents ............................................................................................15

Annex 3 Form Release Agents ............................................................................................................................19

Annex 4 Form Release Agents ............................................................................................................................22

Annex 5 Pre-stressing cable ducts ......................................................................................................................25

Annex 6 Pictures of Formwork Manufacture ......................................................................................................26

Annex 7 Concrete Compressive Strength Test Results ........................................................................................28

ReCAP | Nepal Modular Bridge Fabrication Report iv

Abstract

This research has focused on defining and developing a new modular system of bridge construction for Nepal, which is

suitable for all environments. The motivation for this project came from DoLIDAR with their need to construct up to

2,000 new bridges to support the expansion of the rural road network. A modular bridge for Nepal has been designed

and is being trialled in two locations, one in Doti district (a hilly area in the far west of Nepal) and one in Parsa district

on the flat Terai area of Nepal, to the south west of Kathmandu. This report currently covers the fabrication of the

modules for Baugi Bridge in Parsa, on the Terai.

The report details two visits that have been made to monitor and advise on the fabrication of the bridge modules. The

first visit in May 2019 included an assessment of the steel formwork manufactured for the bridge modules, and advice

on various issues regarding the casting of modules and how the formwork should be set up in the factory. The second

visit in November 2019 was a site visit to the Terai to see the modules being cast and to answer specific queries on the

casting and assembly of the modules.

Key words

Nepal, Modular Bridge, Design, Fabrication, Construction, Pre-stressing

Research for Community Access Partnership (ReCAP)

Safe and sustainable transport for rural communities

ReCAP is a research programme, funded by UK Aid, with the aim of promoting safe and sustainable transport for rural

communities in Africa and Asia. ReCAP comprises the Africa Community Access Partnership (AfCAP) and the Asia

Community Access Partnership (AsCAP). These partnerships support knowledge sharing between participating

countries in order to enhance the uptake of low cost, proven solutions for rural access that maximise the use of local

resources. The ReCAP programme is managed by Cardno Emerging Markets (UK) Ltd.

ReCAP | Nepal Modular Bridge Fabrication Report v

Acronyms

AsCAP Asia Community Access Partnership DFID Department For International Development DoLI Department of Local Infrastructure DoR Department of Roads GoN Government of Nepal LRBP Local Roads Bridge Programme LRBSU Local Roads Bridge Support Unit ReCAP Research for Community Access Partnership TRL Transport Research Laboratory ToR Terms of Reference UK United Kingdom (of Great Britain and Northern Ireland) UKAid United Kingdom Aid (Department for International Development, UK)

ReCAP | Nepal Modular Bridge Fabrication Report vi

Executive Summary

This project aims to provide a new design for modular bridges in Nepal, with one system being preferred for both

Terai and hilly areas. The project was kicked off in Kathmandu on 8th November 2016. A workshop was held soon

after, at which the design principles for the modular bridge were agreed. DoLI noted that they would prefer a design

that maximises the use of concrete, because this is more readily available in Nepal as a local resource whereas steel

has been found to be expensive and more difficult to maintain. A design for the bridge was produced by LRBP, with

the assistance of LRBSU and advice from the Bridge Expert (Milan Kominek).

The project is now at the fabrication stage. Modules for the first bridge have been successfully cast in a controlled

environment, on the Terai near to the bridge site. This report documents the advice and support provided to DoLI and

LRBSU to manufacture the formwork and cast the modules. This was achieved between May and November 2019.

Although the project is behind schedule, it is expected that both bridges can be completed before June 2020.

The Bridge Expert made two visits during this period, one in May 2019 to assess the steel formwork manufactured for

the bridge modules, and advise on various issues regarding the casting of modules and how the formwork should be

set up in the factory, and the second visit in November 2019 which included a site visit to the Terai to see the modules

being cast, and to answer specific queries on the casting and assembly of the modules.

A number of issues were identified by LRBSU and were resolved by the Bridge Expert either remotely, or during the

two visits. These issues are outlined in this report, and the contractor has been instructed on how to rectify these for

the fabrication and construction of the second bridge in the hills. The Bridge Expert is content that the bridge modules

cast are of adequate quality and strength for a modular bridge.

Given the limited time remaining on the project it has been recommended that the team meet with ReCAP to define

what will be possible to achieve during the remaining time in the project. It is likely that a re-scoping will be necessary.

ReCAP | Nepal Modular Bridge Fabrication Report 7

1 Background

Nepal’s economy needs to grow fundamentally to solve the problem of limited transport infrastructure in the country.

Crucial to this aim is the development of roads and bridges. The Government of Nepal (GoN) is fully aware of this

problem and is committed to addressing this issue. GoN has given high priority to bridges and has rapidly increased the

bridge construction budget every year.

The motivation for this project came from DoLIDAR (now DoLI) and is borne out of their need to construct up to 2,000

new bridges to support the expansion of the rural road network. At present they use mainly reinforced in-situ concrete

bridges, which are slow to construct and pose particular challenges with quality control and transport of materials,

especially in hilly areas. The Department of Roads (DoR) also constructs up to 200 bridges per year on the strategic

network. The DoR is interested in learning about a modular system for bridges in Nepal, as many of their bridges in the

hills are short span. DoLI has the capacity to build more than 100 bridges per year. For such a high number of bridges,

it is essential that any solution for bridges in Nepal must be feasible, appropriate, flexible and durable. Given this

information it can be assumed that pre-cast/pre-fabricated modular bridges are a potential solution for bridges on rural

roads in Nepal.

It is understood from the ToR that a modular bridge is one that is formed, largely from pre-fabricated parts that are

manufactured off-site in a controlled environment. The parts are then transported to site and assembled. The modular

bridges designed on this project are of short to medium span and are capable of being assembled and placed without

the use of heavy equipment, maximizing the employment of local labour. Furthermore, the modular bridge system is

adaptable to the varied site and environmental conditions and situations found in Nepal and provides a practical

solution to a wide range of scenarios. The ToR further suggests that the bridge components should be fabricated in

Nepal as this will provide employment and develop local industry and capacity. It is also assumed that maximum use of

local materials will be made, hence the selection of concrete as the key material.

A desk study and literature review of the available technologies and systems of structures for modular bridge

construction from around the world was prepared at inception stage. Meetings with local experts were held, and

information and documents concerning the bridge issue and current state of roads and bridges development in Nepal

were received. Many interesting bridges have recently been completed or are under construction or design in Nepal.

The GoN focuses great attention on developing transport infrastructure, especially roads and bridges, as evidenced by

the various government programmes. An example of this commitment is the National Program for Motorable Bridges

on Local Roads – an assignment under the Local Road Bridge Programme (LRBP), completed in July 2014. The LRBP was

undertaken from February 2011 to July 2016 in Phase I, with Phase II and Phase III to follow. A concept paper on

adaptation of pre-stressed pre-cast modular bridges for Nepal was prepared for the Local Road Bridge Support Unit

(LRBSU) before this project commenced, so the idea of modular bridges in Nepal is not new.

Therefore, this ReCAP project in Nepal has the potential to be the start of important research into the impacts of

modular bridges from a developing country perspective.

2 Introduction

This report includes details on the supervision and advice provided during the formwork production and fabrication of

the bridge modules. Two visits to Nepal were made by the Bridge Expert:

• May 2019 – to check on the manufacturing of bridge formwork and to advise on any improvements necessary, both in making the formwork and in casting the concrete beams.

• November 2019 – to check on the progress of fabrication, including beam casting in a controlled environment and any ancillary measures that were necessary.

Remote advice has been provided throughout this period at the request of DoLI and LRBSU.


3 Site Visits

3.1 May 2019 Visit

The Bridge Expert visited Nepal in May 2019 to meet with stakeholders on the project, to gauge progress of

fabrication and to assess the quality of the formwork that was in manufacture. He was also able to advise on a range

of issues related to the formwork manufacture, as detailed below.

A meeting was held on 29 May 2019 at LRBSU. At this meeting it was agreed, amongst other things, that the assembly

of the modules on the temporary support would be carried out without any epoxy application to the joints, resulting

in dry joints produced by the match cast (positive negative) method. Therefore, visit report points 4 and 6 from 27th

May 2019 do not apply, and the assembly method described in visit report from 28th May 2019 is therefore confirmed

(Annex 1).

This visit summary was compiled on conclusion of the meetings in Kathmandu. It summarises the principle of the

modular design, which is essential for the production and assembly of the bridge modules.

• During fabrication each module should be cast one after another, in a series at the same time (Visit Report

Point 2 from 27th May: Annex 1) with (positive negative) match cast joints by the long-line method, which

should be based on a solid horizontal surface to form the long-line bed (approximately 22 m long for whole

girder). After casting of all the modules of a girder, they must be precisely positioned geometrically on the

formwork, especially the connection point of cable ducts.

• The technical supervision must check and accept the reinforcement of each module from the contractor. In

the support module (module A), typical spiral and other shear reinforcement must be fitted in the anchorage

area, according to the Freyssinet system. The grouting tube for injection must be fitted in the support and

middle modules (module A and module E) and lead to the top surface of the module.

• During module production there must be the possibility to use suitable external vibrators and the formwork

must be robust enough to cope with these vibrations. Use of immersion vibrators only may not be enough to

ensure the quality of concrete in the bottom flanges. Testing by probe pour of two sample modules is

strongly recommended.

• During module production a quality Form Release Agent must be used. TRL Bridge Expert sent to LRBSU

(Shakil Manandhar) on 29th May 2019 information on choosing and using Form Release Agents (Annex 2) and

other information about suitable materials that could be used and available in India and Nepal (Annexes 3

and 4). Only products of declared quality and suitability can be used and testing is strongly recommended.

• During both the manufacturing and assembly of modules, the fixed axis must be maintained to retain the

correct longitudinal geometry of the whole girder.

• During the manufacture of modules, the contractor is responsible for the quality of the concrete and

geometry of the beams, and should perform control tests.

• During manufacture, the longitudinal axis of the whole girder must be straight. To achieve the final shape on

the bridge the girders can be inclined to the desired slope to facilitate drainage of the bridge surface. There is

no camber in the pre-stressed girder.

• When assembling modules on the bridge, it is necessary to ensure that an assembled module is sufficiently

pressed against the previous one, which is already firmly installed and fixed. The correct installation of each

new module should be carefully checked, so that there is no fundamental problem of pre-stressing, and

concentrated compressive stress is avoided.

• Great care must be taken to ensure the correct and exact position of the cable ducts in the joints of the

modules to ensure continuity of the cable (Annex 5). Cable ducts must be precisely aligned at the module

joints. Suitable demountable inserts can help to ensure in locating the position (e.g. a pressured rubber

hose).

• On the construction site, especially during assembly and pre-stressing of modules, permanent strict technical

supervision is highly recommended.


• During the whole construction process, photographic documentation must be carried out by the contractor

and the technical supervisor.

• The possibility of grout being squeezed from the joints and the cable ducts between the modules must be

eliminated. TRL Bridge Expert sent to LRBSU (Shakil Manandhar) information relating to duct couplers

LIASEAL as an option by email on 28 May 2019 (see Annex 5). Other suitable tight couplers are available and

would be options.

This visit was preceded by email correspondence and consultations on progress and problems that arose on the

construction site. On 18 November 2019, Shakil Manandhar sent a message to the Bridge Expert proposing a site visit

the following week. The Bridge Expert was available on 25 November 2019 in Kathmandu and a meeting at LRBSU

took place that Monday between Shakil Manandhar and Ranjan Manandhar of LRBSU, Bishnu Shah and the Bridge

Expert.

There was a discussion on the current progress of construction and a summary of the known state of work activities

carried out at the site. Preparations for the site visit were also made.

The formwork has been manufactured in steel in a controlled environment, at the contractor’s premises in

Kathmandu, as proposed in the design report. The formwork was inspected by the Bridge Expert in May 2019. Upon

inspection the formwork modules were found to be well made and adequate for the purpose of forming modular

sections of reinforced concrete bridge. The fabricated sections of formwork can be seen in Annex 6.

3.2 November 2019 Visit to Bridge 1

This visit was made to Baugi Bridge in Parsa, Bridge 1.

3.2.1 Planning

The Bridge Expert made a visit to Nepal from 25 to 29 November 2019 as requested by DoLI and LRBSU. The visit was

initiated by email correspondence from Shakil Manandhar of LRBSU on 18 November 2019, to consult over progress

and problems that had arisen on the fabrication site. LRBSU proposed a site visit for the following week as the issues

encountered on site were holding up progress. The Bridge Expert indicated that he was available to visit Nepal from

25 November 2019.

Subsequently on 18 November 2019, LRBSU sent materials for testing and analysis to confirm the quality of

construction on site. The results can be seen in Annex 7 of this report, and show that the concrete is of adequate

strength. Following an assessment of the issues raised, it was agreed that a site visit was essential, firstly to experience

the issues first hand and secondly to provide reassurance and confidence to DoLI to proceed with the fabrication and

construction process.

Following consultation with TRL and ReCAP, preparation for the Nepal site visit continued between 19-22 November

2019 in the Prague office of AFCityPlan, as well as ongoing consultations with LRBSU in Kathmandu.

3.2.2 Purpose

This is the first bridge built to a completely new technology in Nepal (Nepal has produced prestressed bridges before,

but only single beams cast in-situ, not as a modular technology), and therefore there is a high probability of problems

occurring as there is no experience of the technology in-country. Bridge 1 at Baugi River in Parsa is located reasonably

close to industrial areas of Birgunj (15 km) and Hetauda (35 km) on the Terai, so it was relatively easy for the

contractor to find a place to fabricate the bridge modules. The location of the fabrication of modules was

approximately 20 km from the bridge site, and the completed modules were transported to the bridge site. Bridge 2 is

much more remote, so the nearest place to find an existing controlled environment would again likely to be on the

Terai, which is the closest industrial area. This would be in excess of 130 km from the bridge site. The problems need

to be identified and addressed as they appear. So far this has happened with the good cooperation of all partners.

The main purpose of this visit to Bridge 1 was:

• To assess the fabrication issues being experienced on site by the contractor, DoLI and LRBSU (see Section 4.1).


• To advise on potential solutions and/or remedial actions as necessary.

• To support the contractor, DoLI and LRBSU to deal with the issues and to give them confidence to proceed with the fabrication and construction.

3.2.3 Visit schedule

The following schedule was undertaken during the visit to Nepal:

• 24 November: The Bridge Expert arrived in Kathmandu and carried out preparations for the site visit meeting at the LRBSU.

• 25 November: Meeting with Shakil Manandhar, Ranjan Manandhar, Bishnu Shah and the Bridge Expert in Kathmandu. There was a discussion on the current progress of construction and a summary of the known state of the work activities at the site. Preparations for the site visit were finalised.

• 26/27 November: The team travelled to the bridge fabrication site. The team included:

➢ Contractor: Anil Silval (ECC/K.M./JBNS – JV)

➢ Designer: Ranjan Manandhar (LRBSU)

➢ Technical supervisor

➢ Bridge Expert: Milan Kominek (TRL team)

• 28 November: Following their return to Kathmandu, further consultations took place at the LRBSU regarding the construction site contract. Feedback from the site confirmed that two more girders had been successfully pre-stressed. Pre-stressing of the bridge structure was therefore completed. This will be covered in the forthcoming Construction Report.

• 29 November: Cable grouting was started on site, following established procedures as advised by the Bridge Expert. This will be covered in the forthcoming Construction Report.

• 30 November: Reporting was continued and processed based on incoming news from the construction site. This will be covered in the forthcoming Construction Report.

• A final site visit report was completed after the Bridge Expert´s return to Prague.

4 Summary

4.1 Issues Identified

Issues were noticed during the assembly and pre-stressing of the bridge. These will be covered in detail in the

construction report, but indicated that:

• There were problems with the girder geometry, including inaccuracies in the production of modules. It was found that the formwork was not precise in its construction. This has been fed back to the contractor and supervisors, and instructions have been given for this to be adjusted before Bridge 2 is cast.

• There was insufficient slip (or sliding) on the platform (construction issue).

• There was insufficient compression strength between modules when assembling modules together on the bridge platform (construction issue).

These issues are important to address for the long-term quality control of modular bridges. Issues such as this are to be expected on a pilot bridge of a new technology, and although they were overcome in this instance and the impact was minimal, they can be prevented in the future through good practice and experience. It is important that the contractor and supervisors embrace the advice given and apply it to the forthcoming construction of Bridge 2. The contractor has been instructed in how to resolve these issues and LRBSU are competent to supervise their implementation.


4.2 Present Status

Fabrication of the first bridge modules for the Baugi River Bridge is now 100% completed. Casting and assembly of

modules, pre-stressing and grouting is ongoing and concreting of the composite interacting deck slab is due to

commence on site during December 2019. This will complete the superstructure of the bridge.

The concrete quality of the bridge modules at M45 was achieved without any issues.

Overall the quality of production was deemed by the Bridge Expert to be adequate for local conditions and was

deemed to be successful with the cooperation of all stakeholders. Production of the concrete modules at the end of

the rainy season and assembly during the dry season showed the advantage of this proposed technology in terms of

year-round construction scheduling.

The current course of this research project, including its implementation, has shown the suitability of the proposed

new bridge construction technology in Nepal. The objective of this research project was to find a suitable method for

the construction of modular bridges in Nepal. On the basis of extensive analysis of the problem, taking into account

the specific conditions in Nepal, and after intensive consultation and cooperation with Nepalese experts, the method

of prefabrication of prestressed concrete girders was chosen.The designs were found to be appropriate and fulfil the

requirements identified at the beginning of the project; concrete was the preferred material because it is available

locally, the design of limited weight and length prefabricated sections was selected to facilitate transport to remote

locations and prefabrication in a controlled environment negated the influence of the monsoon season. The suitability

of this method is demonstrated by the implementation of the trial bridges, so no substantial changes are needed.

4.3 Next Steps

Load testing of the first bridge will need to be carried out after completion of assembly, pre-stressing of the beams

and curing of the deck slab. This will be supervised by the Bridge Expert and the results included in the Construction

Report.

Fabrication for the second bridge at Golmagad Khola in Doti has commenced. The formwork has been transferred to

this site and to date seven modules have been fabricated. There have been some access issues due to the poor

condition of the access road; the contractor has requested the responsible person of the municipality to improve the

road, but they have yet to respond to this request.

The contractor has requested DoLI for permission to cast the modules on site rather than in his production yard due to

the poor condition of the access road and the perceived difficulties in transporting modules to the bridge site. The

research team has no objection to this course of action, as communicated by email to stakeholders on 12 December

2019. Essential conditions are set out in the email, including the quality of concrete, the manufacturing accuracy and

preparation of the sliding bed for production and assembly of the modules, and final cable pre-stressing (including

temporary fastening and pressing the modules together). The Bridge Expert also stressed that lessons learned during

the first bridge fabrication should be implemented for the second. Feedback from site so far is that there have been

some issues with equipment, which takes time to fix as the nearest maintenance facility is a round trip of almost

250km. This highlights the importance of fabricating in a controlled environment with good facilities, where possible.

The construction of the first bridge was completed in early January 2020, and the second bridge is expected to be

completed by the end of April 2020.

It should be noted that it was agreed TRL would support one bridge with active inputs, such as site visits. It is

therefore recommended that a re-scoping meeting is held with TRL, client and subcontractor to formally plan the

remaining 5 months of the project and agree on what can be achieved, including the manual, training courses and cost

benefit analysis. The second bridge will be supported remotely, mainly by the Bridge Expert.

When this report is approved it will be forwarded to DoLI and stakeholders for response.


Annex 1 Meetings held on 27 & 28 May 2019




Annex 2 Selection and use of Form Release Agents





Annex 3 Form Release Agents




Annex 4 Form Release Agents




Annex 5 Pre-stressing cable ducts


Annex 6 Pictures of Formwork Manufacture



Annex 7 Concrete Compressive Strength Test Results















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Investigation of the Suitability of Pre-cast/Pre- Fabricated Modular ...research4cap.org/...TRL-2020-SuitabilityModularBridgesRuralRoadsN… · bridges, which are slow to construct