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The next chapter of Mumbai's "dangerous" small bridges

 
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alpa_sheth
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Joined: 26 Jan 2003
Posts: 259
Location: Mumbai

PostPosted: Sun Aug 25, 2019 9:43 am    Post subject: The next chapter of Mumbai's "dangerous" small bridges Reply with quote

Dear All:

In response  to the earlier articles on Urban Infrastructure I had shared on this forum, I thought I will share with you the follow-up on those pieces. I think  we need to find effective ways of engaging with authorities. We will all fail if we try as individuals But as a community, we are hard to ignore.
  
https://www.moneylife.in/article/mumbai-infrastructure-citizens-technical-advisory-committee-tries-to-bridge-the-gap/57942.html

It is reproduced here for an easy read.
  
warmly,

Alpa
Mumbai Infrastructure: Citizens' Technical Advisory Committee Tries to Bridge the Gap
Alpa Sheth

On 14 March 2019, the Himalaya bridge floor at the northern end of the Chhatrapati Shivaji Maharaj Terminus (CSMT) gave way in part, causing six deaths. The incident happened in the island city in peak traffic, at a railhead, literally under the nose of the Municipal Corporation of Greater Mumbai (MCGM). CSMT is the jewel in the crown of Mumbai's glory.

There was uncontrolled rage fanned by 24x7 national television coverage, and in typical developing-world style, scapegoats had to be immediately identified and punished to assuage the angry mob. The hapless assistant and executive engineers were arrested along with the audit consultant and the retired chief engineer (bridges). And with astounding alacrity, bridges that had been steadily plying traffic and earlier deemed safe were overnight labelled unfit for vehicular movement by a set of understandably nervous and overcautious audit engineers, and tagged for demolition. Without any thought spared for alternative travel routes and socio-economic losses that this would entail, many of the marked bridges were demolished without further ado.

The Formation of CTAC

Moneylife Foundation ran a couple of my stories on the topic in May 2019 under the title "Mumbai's Crumbling Infrastructure" (https://www.moneylife.in/article/mumbais-crumbling-infrastructure-are-we-burning-our-bridges-before-crossing-them-part-1/57227.html & https://www.moneylife.in/article/mumbais-crumbling-infrastructure-knee-jerk-solutions-leave-mumbais-lifeline-without-a-spine-part-2/57233.html), which identified the flawed process of management and review of the existing infrastructure and lack of institutionalised systems and procedures of maintenance. Moneylife followed it up with a talk on the same issue (https://www.moneylife.in/article/mumbais-infrastructure-woes-is-fear-psychosis-leading-to-poor-unqualified-decisions/57391.html).

The ensuing discussion generated constructive suggestions and participants included renowned engineer Shirish Patel and politician and social worker Sanjay Nirupam, along with eminent activists and subject experts in the field. A proposal emerged to meet the Municipal Commissioner to discuss the possibility of a second review of some of the balance bridges marked for demolition by a set of eminent city engineers; a meeting (organized by Sanjay Nirupam and Sucheta Dalal) with the Municipal Commissioner was held on the 26 June 2019 at the latter's office and resulted in the formation of a Citizens' Technical Advisory Committee (CTAC) with three private engineers (Mr Patel as chairman of the committee, Dr VV Nori and myself), a faculty member each from VJTI and IIT Bombay, and the Chief Engineer (Bridges) from MCGM as member secretary. (https://www.moneylife.in/article/bmc-sets-up-new-advisory-panel-on-bridges/57556.html).

What follows is a brief account of the Committee's work and the lessons learnt from a very interesting experience of a PPP (public-private partnership) in unchartered territory. As a preamble, the incumbent Municipal Commissioner, Mr. Praveen Pardeshi deserves full credit to have set up the Committee against all odds. The position of the Municipal Commissioner of the Maximum City comes with a crown of thorns -- but Mr. Pardeshi appears to wear the crown stoically.

The objective of this account is to illustrate one among a myriad possibilities for constructive intervention by citizens' initiatives and, going forward, put in place a template for formal procedures to engage with authorities effectively to create a win-win situation for the establishment and the public at large.

Encounter with the Bridges Department

A kick-off meeting of the CTAC was held at the office of the chief engineer (CE) bridges on the 28th June which was attended by the chief engineer, deputy chief engineer and numerous executive and superintending engineers of the bridge department, and CTAC members from the private sector. The bridges department has seen many mergers and demergers in its chequered history. An independent department originally, it was merged with the department of roads and traffic in mid-November 2006 and was again carved out as a separate department in 2013.

Since then, the bridge department has had to deal with fatalities related to deficiencies or failures of - bridges on an annual basis and respond to angry citizens, politicians and face relentless media scrutiny. So there we were, sitting in a fledgling department (a six-year-old in the 132 year history of the mother MCGM) whose first chief engineer was presently in jail and two colleagues of the engineers seated across the table from us were still in custody. It is thus hardly surprising that the department would view any new external agency with suspicion. While the stated objectives of the CTAC were unarguably noble, it was foisted upon a department with frayed nerves. To them, CTAC was another nuisance to be dealt with.

The Hurdles

The department informed CTAC that it had been conducting a comprehensive structural audit program of 327 bridges under its purview since 2016 through three consultants. On further enquiry, it emerged that the department did not have standard operating procedures (and checklists) for conducting bridge audits and each consultant was conducting the audit based on individual capacity. Left to their devices, auditors simply tagged bridges which in their opinion were unfit for vehicular movement as "fit for demolition".

A more nuanced approach to bridge condition survey is called for, rather than a bipolar "good" or "fit for demolition" approach. Oftentimes, bridge life may be extended by simple retrofit measures. Bridge retrofit, wherever possible, can not only save capital expenditure, but also avoid undue inconvenience to citizens caused by extended route closures. Alternately, only a part of the bridge may need replacement. The foundations for example could be in good condition and only the superstructure may need to be replaced.

The department was not in possession of the original design documents, nor did it possess historical documentation of the repairs and modifications to each of the bridges, quite unlike the British legacy of auditing the bridges through its own in-house engineers and keeping a detailed repair and maintenance log for every bridge they built. Our first visit to the department left us with an uncomfortable feeling that the department was harried by the absence of systems, procedures, capacity-building programs and a credible database of its assets.

CTAC's Groundwork Begins

In the aftermath of the 14th March incident (the Himalaya bridge had passed the safety audit), the audit of all bridges had been repeated and 29 bridges were deemed to be unsafe and were thus tagged for demolition. Of these, fifteen had already been demolished prior to our meeting and the department was in a position to offer 10 bridges for review to the CTAC. Closure of some of these bridges had evoked a strong response from the community, so any small contribution to a quick resolution of the bridge closure issue would be of much value.

Subsequent to the meeting, CTAC commenced the exercise of reviewing the bridges. The objective of the CTAC was to inspect the bridges to see the possibility of temporarily opening the bridges to ease the travails of the public for about six months until a more long term solution was put in place. Audit reports for the bridges marked for inspection were shared by the department.

In the subsequent two weeks, CTAC conducted numerous site visits to five bridges at Juhu Tara, Oshiwara, Laxmi Baug at Ghatkbopar-Andheri Link Road, Krishna Kunj at Malad and the Dhobi Ghat bridge, along with BMC's executive engineer and/or deputy chief engineer.

Corrosion Pervades

All the bridges under review were minor bridges and showed a similar distress pattern -- significant corrosion of the bottom reinforcement bars of the bridge deck slab. There was some minor deformation observed at some bridges. It was not possible to observe any cracking as access to the underside of the bridge was not possible.

Drone photography was able to capture the corrosion of the reinforcement but not any cracks in the concrete. The deterioration has likely been caused by a combination of all or some of these factors- a) inadequate cover to the reinforcement bars at the time of construction of the bridge b) original concrete did not have adequate denseness and durability c) environment was highly aggressive/ corrosive/polluted d) Poor implementation of an inspection and maintenance program.

The CTAC was of the opinion that the bridges at Oshiwara and Juhu Tara did not show any noticeable distress at the piers and foundations. While reinforcement corrosion of the slab was evident in the photographs, CTAC did not believe that the bridge was in imminent danger of a sudden and brittle failure and suggested that the bridge be opened in a phased manner to light vehicles and BEST buses (but not trucks) almost immediately, after the removal of overburden load due to incremental topping over the years and after some other minor modifications were implemented. Bridge deformation was to be monitored.

Retrofit as the Right Strategy

Retrofit to the bridge at Laxmi Baug was already underway during CTAC's visit to the site. The retrofit strategy entailed providing additional steel girders supported on freshly raised outcrops of the supporting piers over the bridge slab and supporting a chequered plate ramp on steel joists, thus relieving the underlying concrete slab of any superimposed load of vehicular traffic. CTAC was in agreement with this retrofit strategy as it ticked all the right boxes for a good strengthening system. The retrofit was quick, clean (almost no concreting involved and the steel members could be cut to size and brought to site), reversible and had salvage value when the bridge would be demolished.

The Krishna Kunj bridge at Malad had been load tested and the testing agency had recommended allowing light vehicles (no trucks) to be plied over it. CTAC concurred with the decision. The Dhobi Ghat bridge had been forced open by residents and users at the time of CTAC's visit. The committee was of the opinion that while the bridge could be opened for light vehicular traffic, an entry barrier needed to be in place for disallowing truck movement.

CTAC cleared all of the five bridges inspected by them for light vehicular movement with minor or no modifications up till 11 July 2019, barely 14 days since its formation. The balance five bridges that were marked for demolition were not offered for inspection to CTAC as they had already been opened to light traffic.

MCGM in a Dilemma

The MCGM bridges department found itself in an awkward situation. Prior to CTAC's bridge inspection and recommendations, the department had received a divergent opinion from VJTI for the bridges at Juhu Tara and Oshiwara. The faculty member had recommended strengthening the deck slab of the bridge by laying a 300 mm reinforced concrete slab over the existing deck. The consultants in CTAC were not in favour of this solution and considered it an uncalled for expenditure of the state's resources - a waste of the public's time and the Corporation's money. In their opinion, during construction the additional concrete would add further deadweight to the underlying deck slab. There was no value being attained by providing this additional slab and its absence was no worse than its presence.  

No Records

A strong case was made for this solution by the faculty member and the bridges department, based on the deformations for these bridges obtained during load testing of the bridge. But ironically there was no report of the load tests (these are expensive tests) available with MCGM for any of the bridges.


The procedure of the purported test, based on oral accounts, involved the use of tubes and measuring water levels which in CTAC's opinion seemed to have been unnecessarily primitive when sophisticated instruments for measuring levels are available and a code --Indian Roads Congress IRC:SP:51-2015 "Guidelines for Load Testing of Bridges" specifies how load testing should be done. The testing records kept were incomplete and casual and no final report was submitted to the department. In such a situation, CTAC was unable to draw reliable conclusions about the overall safety (or lack of it) of the bridge from the load test. All that could be said was that if the bridge had sustained the load of a battery of 32 tonne trucks, followed by partial elastic recovery, the bridge could safely carry light-weight traffic, including buses but not trucks.


The MCGM bridges department demanded a safety guarantee from CTAC if its opinion was to be heeded. It was disingenuous of the bridges department to make a request as such since it had not issued a formal letter of appointment regarding the constitution of the Citizens Technical Advisory Committee and its terms of reference. (This was also the reason, I believe, why the faculty from IIT refused to participate in any of the proceedings of the CTAC).


CTAC was a voluntary initiative to enable the bridges department to identify the key issues and challenges with respect to safety of their bridges. It was not a body formed for formal structural audit commissioned by MCGM. Nevertheless, two of the CTAC members gave such a certification in writing. One would assume that the demand for such a certificate implies that if it is given, it will be accepted and acted upon by opening the bridge to traffic.

BMC Disregards but CTAC Persists

Despite receipt of the written assurance from two members of the CTAC in their personal capacity, the department went ahead with the faculty member's advice of providing an additional reinforced concrete slab of 300 mm at the Juhu Tara bridge. The CTAC was understandably upset with the decision. After a meeting with the municipal commissioner, a second visit to the Oshiwara bridge was organised and based on the visit, CTAC was able to impress upon the department that providing the 300 mm additional slab on the Oshiwara bridge was not necessary. Tens of lakhs of rupees would saved in the process, besides further months of inconvenience of the public. Let us see what actually happens.  

Recommendations

It would be very useful for the bridges department of MCGM to undertake a capacity building exercise for its team and its consultants' teams to ensure competency, consistency and credibility in the bridge inspection, audit and maintenance program. An institutionalised training program also helps in seamless induction of new engineers into the system.

The writer would like to acknowledge the pivotal role played by Moneylife Foundation and Sanjay Nirupam and Sucheta Dalal, especially, in enabling the entire endeavour.

Mr Shirish Patel and Dr V V Nori have contributed significantly to the writing of this report.

(Alpa Sheth is managing director of VMS Consultants Pvt Ltd, a structural engineering firm in Mumbai. Ms Sheth is co-founder and managing Trustee of Structural Engineers Forum of India -SEFI (www.sefindia.org) and is a member of many drafting groups of the Bureau of Indian Standards

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diwakar bhagat
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PostPosted: Sun Aug 25, 2019 11:30 am    Post subject: The next chapter of Mumbai's "dangerous" small bridges Reply with quote

Please understand


The English people as a group of technical expert are handling and facing problems of certification of set of oldest bridges on the planet, almost as old as 500 years, They have evolved a set of procedures of evaluation methodology process, maintenance and record keeping ‎.
Why can't we adopt similar thing and technical administrative wing in the country?
District engineers, was the right term for a technical head for all infrastructure development, decision making at administrative level, as named by the english
In our country with current administrative decisions not being channelised from a single source, who is to be technically heading as well as heading ‎administratively to take correct decision,we are not heading towards the correct manner.


Problem is not in achieving a big pool of knowledge source and big pool of learned people to implement, instead problem lies in decision making at administrative level which allows to have a set procedure, team and fund allocation with a head (technical) made responsible at ‎admistrative level for all such infrastructural work in each district.


Must have District ‎Engineers on par like district magistrates for infra in each district.




Regards


Dr Diwakar ‎Bhagat


Sent from my BlackBerry 10 smartphone.
From: alpa_sheth
Sent: Sunday 25 August 2019 15:15
To: general@sefindia.org
Reply To: general@sefindia.org
Subject: [SEFI] The next chapter of Mumbai's "dangerous" small bridges



Dear All:
In response to the response to the earlier articles on Urban Infrastructure I had shared on this forum, I thought I will share with you the follow-up on those pieces. I think as a we need to find effective ways of engaging with authorities. We will all fail if we try as individuals But as a community, we are hard to ignore.
https://www.moneylife.in/article/mumbai-infrastructure-citizens-technical-advisory-committee-tries-to-bridge-the-gap/57942.html
It is reproduced here for an easy read.
warmly,
Alpa

Mumbai Infrastructure: Citizens' Technical Advisory Committee Tries to Bridge the Gap
Alpa Sheth

On 14 March 2019, the Himalaya bridge floor at the northern end of the Chhatrapati Shivaji Maharaj Terminus (CSMT) gave way in part, causing six deaths. The incident happened in the island city in peak traffic, at a railhead, literally under the nose of the Municipal Corporation of Greater Mumbai (MCGM). CSMT is the jewel in the crown of Mumbai's glory.

There was uncontrolled rage fanned by 24x7 national television coverage, and in typical developing-world style, scapegoats had to be immediately identified and punished to assuage the angry mob. The hapless assistant and executive engineers were arrested along with the audit consultant and the retired chief engineer (bridges). And with astounding alacrity, bridges that had been steadily plying traffic and earlier deemed safe were overnight labelled unfit for vehicular movement by a set of understandably nervous and overcautious audit engineers, and tagged for demolition. Without any thought spared for alternative travel routes and socio-economic losses that this would entail, many of the marked bridges were demolished without further ado.

The Formation of CTAC

Moneylife Foundation ran a couple of my stories on the topic in May 2019 under the title "Mumbai's Crumbling Infrastructure" (https://www.moneylife.in/article/mumbais-crumbling-infrastructure-are-we-burning-our-bridges-before-crossing-them-part-1/57227.html & https://www.moneylife.in/article/mumbais-crumbling-infrastructure-knee-jerk-solutions-leave-mumbais-lifeline-without-a-spine-part-2/57233.html), which identified the flawed process of management and review of the existing infrastructure and lack of institutionalised systems and procedures of maintenance. Moneylife followed it up with a talk on the same issue (https://www.moneylife.in/article/mumbais-infrastructure-woes-is-fear-psychosis-leading-to-poor-unqualified-decisions/57391.html).

The ensuing discussion generated constructive suggestions and participants included renowned engineer Shirish Patel and politician and social worker Sanjay Nirupam, along with eminent activists and subject experts in the field. A proposal emerged to meet the Municipal Commissioner to discuss the possibility of a second review of some of the balance bridges marked for demolition by a set of eminent city engineers; a meeting (organized by Sanjay Nirupam and Sucheta Dalal) with the Municipal Commissioner was held on the 26 June 2019 at the latter's office and resulted in the formation of a Citizens' Technical Advisory Committee (CTAC) with three private engineers (Mr Patel as chairman of the committee, Dr VV Nori and myself), a faculty member each from VJTI and IIT Bombay, and the Chief Engineer (Bridges) from MCGM as member secretary. (https://www.moneylife.in/article/bmc-sets-up-new-advisory-panel-on-bridges/57556.html).

What follows is a brief account of the Committee's work and the lessons learnt from a very interesting experience of a PPP (public-private partnership) in unchartered territory. As a preamble, the incumbent Municipal Commissioner, Mr. Praveen Pardeshi deserves full credit to have set up the Committee against all odds. The position of the Municipal Commissioner of the Maximum City comes with a crown of thorns -- but Mr. Pardeshi appears to wear the crown stoically.

The objective of this account is to illustrate one among a myriad possibilities for constructive intervention by citizens' initiatives and, going forward, put in place a template for formal procedures to engage with authorities effectively to create a win-win situation for the establishment and the public at large.

Encounter with the Bridges Department

A kick-off meeting of the CTAC was held at the office of the chief engineer (CE) bridges on the 28th June which was attended by the chief engineer, deputy chief engineer and numerous executive and superintending engineers of the bridge department, and CTAC members from the private sector. The bridges department has seen many mergers and demergers in its chequered history. An independent department originally, it was merged with the department of roads and traffic in mid-November 2006 and was again carved out as a separate department in 2013.

Since then, the bridge department has had to deal with fatalities related to deficiencies or failures of - bridges on an annual basis and respond to angry citizens, politicians and face relentless media scrutiny. So there we were, sitting in a fledgling department (a six-year-old in the 132 year history of the mother MCGM) whose first chief engineer was presently in jail and two colleagues of the engineers seated across the table from us were still in custody. It is thus hardly surprising that the department would view any new external agency with suspicion. While the stated objectives of the CTAC were unarguably noble, it was foisted upon a department with frayed nerves. To them, CTAC was another nuisance to be dealt with.

The Hurdles

The department informed CTAC that it had been conducting a comprehensive structural audit program of 327 bridges under its purview since 2016 through three consultants. On further enquiry, it emerged that the department did not have standard operating procedures (and checklists) for conducting bridge audits and each consultant was conducting the audit based on individual capacity. Left to their devices, auditors simply tagged bridges which in their opinion were unfit for vehicular movement as "fit for demolition".

A more nuanced approach to bridge condition survey is called for, rather than a bipolar "good" or "fit for demolition" approach. Oftentimes, bridge life may be extended by simple retrofit measures. Bridge retrofit, wherever possible, can not only save capital expenditure, but also avoid undue inconvenience to citizens caused by extended route closures. Alternately, only a part of the bridge may need replacement. The foundations for example could be in good condition and only the superstructure may need to be replaced.

The department was not in possession of the original design documents, nor did it possess historical documentation of the repairs and modifications to each of the bridges, quite unlike the British legacy of auditing the bridges through its own in-house engineers and keeping a detailed repair and maintenance log for every bridge they built. Our first visit to the department left us with an uncomfortable feeling that the department was harried by the absence of systems, procedures, capacity-building programs and a credible database of its assets.

CTAC's Groundwork Begins

In the aftermath of the 14th March incident (the Himalaya bridge had passed the safety audit), the audit of all bridges had been repeated and 29 bridges were deemed to be unsafe and were thus tagged for demolition. Of these, fifteen had already been demolished prior to our meeting and the department was in a position to offer 10 bridges for review to the CTAC. Closure of some of these bridges had evoked a strong response from the community, so any small contribution to a quick resolution of the bridge closure issue would be of much value.

Subsequent to the meeting, CTAC commenced the exercise of reviewing the bridges. The objective of the CTAC was to inspect the bridges to see the possibility of temporarily opening the bridges to ease the travails of the public for about six months until a more long term solution was put in place. Audit reports for the bridges marked for inspection were shared by the department.

In the subsequent two weeks, CTAC conducted numerous site visits to five bridges at Juhu Tara, Oshiwara, Laxmi Baug at Ghatkbopar-Andheri Link Road, Krishna Kunj at Malad and the Dhobi Ghat bridge, along with BMC's executive engineer and/or deputy chief engineer.

Corrosion Pervades

All the bridges under review were minor bridges and showed a similar distress pattern -- significant corrosion of the bottom reinforcement bars of the bridge deck slab. There was some minor deformation observed at some bridges. It was not possible to observe any cracking as access to the underside of the bridge was not possible.

Drone photography was able to capture the corrosion of the reinforcement but not any cracks in the concrete. The deterioration has likely been caused by a combination of all or some of these factors- a) inadequate cover to the reinforcement bars at the time of construction of the bridge b) original concrete did not have adequate denseness and durability c) environment was highly aggressive/ corrosive/polluted d) Poor implementation of an inspection and maintenance program.

The CTAC was of the opinion that the bridges at Oshiwara and Juhu Tara did not show any noticeable distress at the piers and foundations. While reinforcement corrosion of the slab was evident in the photographs, CTAC did not believe that the bridge was in imminent danger of a sudden and brittle failure and suggested that the bridge be opened in a phased manner to light vehicles and BEST buses (but not trucks) almost immediately, after the removal of overburden load due to incremental topping over the years and after some other minor modifications were implemented. Bridge deformation was to be monitored.

Retrofit as the Right Strategy

Retrofit to the bridge at Laxmi Baug was already underway during CTAC's visit to the site. The retrofit strategy entailed providing additional steel girders supported on freshly raised outcrops of the supporting piers over the bridge slab and supporting a chequered plate ramp on steel joists, thus relieving the underlying concrete slab of any superimposed load of vehicular traffic. CTAC was in agreement with this retrofit strategy as it ticked all the right boxes for a good strengthening system. The retrofit was quick, clean (almost no concreting involved and the steel members could be cut to size and brought to site), reversible and had salvage value when the bridge would be demolished.

The Krishna Kunj bridge at Malad had been load tested and the testing agency had recommended allowing light vehicles (no trucks) to be plied over it. CTAC concurred with the decision. The Dhobi Ghat bridge had been forced open by residents and users at the time of CTAC's visit. The committee was of the opinion that while the bridge could be opened for light vehicular traffic, an entry barrier needed to be in place for disallowing truck movement.

CTAC cleared all of the five bridges inspected by them for light vehicular movement with minor or no modifications up till 11 July 2019, barely 14 days since its formation. The balance five bridges that were marked for demolition were not offered for inspection to CTAC as they had already been opened to light traffic.

MCGM in a Dilemma

The MCGM bridges department found itself in an awkward situation. Prior to CTAC's bridge inspection and recommendations, the department had received a divergent opinion from VJTI for the bridges at Juhu Tara and Oshiwara. The faculty member had recommended strengthening the deck slab of the bridge by laying a 300 mm reinforced concrete slab over the existing deck. The consultants in CTAC were not in favour of this solution and considered it an uncalled for expenditure of the state's resources - a waste of the public's time and the Corporation's money. In their opinion, during construction the additional concrete would add further deadweight to the underlying deck slab. There was no value being attained by providing this additional slab and its absence was no worse than its presence.

No Records

A strong case was made for this solution by the faculty member and the bridges department, based on the deformations for these bridges obtained during load testing of the bridge. But ironically there was no report of the load tests (these are expensive tests) available with MCGM for any of the bridges.


The procedure of the purported test, based on oral accounts, involved the use of tubes and measuring water levels which in CTAC's opinion seemed to have been unnecessarily primitive when sophisticated instruments for measuring levels are available and a code --Indian Roads Congress IRC:SP:51-2015 "Guidelines for Load Testing of Bridges" specifies how load testing should be done. The testing records kept were incomplete and casual and no final report was submitted to the department. In such a situation, CTAC was unable to draw reliable conclusions about the overall safety (or lack of it) of the bridge from the load test. All that could be said was that if the bridge had sustained the load of a battery of 32 tonne trucks, followed by partial elastic recovery, the bridge could safely carry light-weight traffic, including buses but not trucks.


The MCGM bridges department demanded a safety guarantee from CTAC if its opinion was to be heeded. It was disingenuous of the bridges department to make a request as such since it had not issued a formal letter of appointment regarding the constitution of the Citizens Technical Advisory Committee and its terms of reference. (This was also the reason, I believe, why the faculty from IIT refused to participate in any of the proceedings of the CTAC).


CTAC was a voluntary initiative to enable the bridges department to identify the key issues and challenges with respect to safety of their bridges. It was not a body formed for formal structural audit commissioned by MCGM. Nevertheless, two of the CTAC members gave such a certification in writing. One would assume that the demand for such a certificate implies that if it is given, it will be accepted and acted upon by opening the bridge to traffic.

BMC Disregards but CTAC Persists

Despite receipt of the written assurance from two members of the CTAC in their personal capacity, the department went ahead with the faculty member's advice of providing an additional reinforced concrete slab of 300 mm at the Juhu Tara bridge. The CTAC was understandably upset with the decision. After a meeting with the municipal commissioner, a second visit to the Oshiwara bridge was organised and based on the visit, CTAC was able to impress upon the department that providing the 300 mm additional slab on the Oshiwara bridge was not necessary. Tens of lakhs of rupees would saved in the process, besides further months of inconvenience of the public. Let us see what actually happens.

Recommendations

It would be very useful for the bridges department of MCGM to undertake a capacity building exercise for its team and its consultants' teams to ensure competency, consistency and credibility in the bridge inspection, audit and maintenance program. An institutionalised training program also helps in seamless induction of new engineers into the system.

The writer would like to acknowledge the pivotal role played by Moneylife Foundation and Sanjay Nirupam and Sucheta Dalal, especially, in enabling the entire endeavour.

Mr Shirish Patel and Dr V V Nori have contributed significantly to the writing of this report.

(Alpa Sheth is managing director of VMS Consultants Pvt Ltd, a structural engineering firm in Mumbai. Ms Sheth is co-founder and managing Trustee of Structural Engineers Forum of India -SEFI (www.sefindia.org) and is a member of many drafting groups of the Bureau of Indian Standards

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diwakar bhagat
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Posts: 11

PostPosted: Sun Aug 25, 2019 5:30 pm    Post subject: The next chapter of Mumbai's "dangerous" small bridges Reply with quote

Please understand


The English people as a group of technical expert are handling and facing problems of certification of set of oldest bridges on the planet, almost as old as 500 years, They have evolved a set of procedures of evaluation methodology process, maintenance and record keeping ‎.
Why can't we adopt similar thing and technical administrative wing in the country?
District engineers, was the right term for a technical head for all infrastructure development, decision making at administrative level, as named by the english
In our country with current administrative decisions not being channelised from a single source, who is to be technically heading as well as heading ‎administratively to take correct decision,we are not heading towards the correct manner.


Problem is not in achieving a big pool of knowledge source and big pool of learned people to implement, instead problem lies in decision making at administrative level which allows to have a set procedure, team and fund allocation with a head (technical) made responsible at ‎admistrative level for all such infrastructural work in each district.


Must have District ‎Engineers on par like district magistrates for infra in each district.




Regards


Dr Diwakar ‎Bhagat

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N. Prabhakar
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PostPosted: Tue Aug 27, 2019 6:16 am    Post subject: Reply with quote

Dear Ms. Alpa Sheth,

The reasons for collapse of Himalaya bridge floor at the northern end of the Chhatrapati Shivaji Maharaj Terminus (CSMT) have already been discussed in this forum under the heading "Mumbai foot bridge collapse" in 16-19 March 2019 with the following link:

https://www.sefindia.org/forum/viewtopic.php?p=81368&highlight=#81368

Only 4 Sefians participated in the discussion. The topic didn't receive much attention then from fellow Sefians.   The following points were highlighted in the discussion:

In My opinion, the sudden collapse of the bridge deck is due to shear failure of the cross beam joint at the truss location due to high corrosion.  It is not the case of flexural failure due to overloading of the beams supporting the bridge deck as such failures give enough warning with large deflection before collapse.  As the beam joint with the truss is not accessible due to bridge deck laid over it, there may not be any maintenance done over a period of 30 years to stop corrosion at the joint location.  The corrosion at the joint must have caused thinning down of supporting members considerably  at the joint location which has resulted in sudden shear failure.

The  mechanism of failure is that one of the cross steel beam  alone has suddenly collapsed due to shear failure of corroded parts at the support joints, there by the concrete deck slab and tiles over the collapsed steel beam  is over hanging from the adjacent steel beam due to effective tying provided by bedding of the tiles over the deck slab.   This leads to increased load on the adjacent steel beam from 1 span load to 1.5 span load which immediately causes adjacent steel beam with over hanging deck slab and tiles over it also to collapse due to  shear failure at support joints.  This mechanism continues immediately with series of collapse one after the other, of all the adjacent steel beams and the deck slab and tiles over it.

There is an inherited fault in the structural system of supporting the
concrete bridge deck slab over structural steel members where the access to maintenance of steel members against corrosion was not possible due to over laying of the deck slab.  If this system has been adopted in other bridges of Mumbai, certainly all of them are in the danger of collapse.  

A high headed committee had been formed to look into this failure, instead of finding a long-term technical  solution to avoid such failures in future, they are only busy in finding who is responsible for that failure.

I do not know the committee's recommendations for construction of new bridges replacing the collapsed ones, without having the same  earlier structural system.

With best wishes,

N. Prabhakar
Chartered Structural Engineer
Vasai (E), Pin 401 208
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Dr. N. Subramanian
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PostPosted: Fri Aug 30, 2019 3:55 am    Post subject: Re: The next chapter of Mumbai's "dangerous" small bridges Reply with quote

Dear Er Alpa,

I read your article on Mumbai's dangerous bridges and I wish to appreciate you for this excellent reporting of the committee's work on the status of current small bridges in Mumbai. Wish you, Dr Noori, Er  Shirish Patel and other committee members all the best.

Warm regards
Subramanian

alpa_sheth wrote:
Dear All:

In response  to the earlier articles on Urban Infrastructure I had shared on this forum, I thought I will share with you the follow-up on those pieces. I think  we need to find effective ways of engaging with authorities. We will all fail if we try as individuals But as a community, we are hard to ignore.
  
https://www.moneylife.in/article/mumbai-infrastructure-citizens-technical-advisory-committee-tries-to-bridge-the-gap/57942.html

It is reproduced here for an easy read.
  
warmly,

Alpa
Mumbai Infrastructure: Citizens' Technical Advisory Committee Tries to Bridge the Gap
Alpa Sheth

On 14 March 2019, the Himalaya bridge floor at the northern end of the Chhatrapati Shivaji Maharaj Terminus (CSMT) gave way in part, causing six deaths. The incident happened in the island city in peak traffic, at a railhead, literally under the nose of the Municipal Corporation of Greater Mumbai (MCGM). CSMT is the jewel in the crown of Mumbai's glory.

There was uncontrolled rage fanned by 24x7 national television coverage, and in typical developing-world style, scapegoats had to be immediately identified and punished to assuage the angry mob. The hapless assistant and executive engineers were arrested along with the audit consultant and the retired chief engineer (bridges). And with astounding alacrity, bridges that had been steadily plying traffic and earlier deemed safe were overnight labelled unfit for vehicular movement by a set of understandably nervous and overcautious audit engineers, and tagged for demolition. Without any thought spared for alternative travel routes and socio-economic losses that this would entail, many of the marked bridges were demolished without further ado.

The Formation of CTAC

Moneylife Foundation ran a couple of my stories on the topic in May 2019 under the title "Mumbai's Crumbling Infrastructure" (https://www.moneylife.in/article/mumbais-crumbling-infrastructure-are-we-burning-our-bridges-before-crossing-them-part-1/57227.html & https://www.moneylife.in/article/mumbais-crumbling-infrastructure-knee-jerk-solutions-leave-mumbais-lifeline-without-a-spine-part-2/57233.html), which identified the flawed process of management and review of the existing infrastructure and lack of institutionalised systems and procedures of maintenance. Moneylife followed it up with a talk on the same issue (https://www.moneylife.in/article/mumbais-infrastructure-woes-is-fear-psychosis-leading-to-poor-unqualified-decisions/57391.html).

The ensuing discussion generated constructive suggestions and participants included renowned engineer Shirish Patel and politician and social worker Sanjay Nirupam, along with eminent activists and subject experts in the field. A proposal emerged to meet the Municipal Commissioner to discuss the possibility of a second review of some of the balance bridges marked for demolition by a set of eminent city engineers; a meeting (organized by Sanjay Nirupam and Sucheta Dalal) with the Municipal Commissioner was held on the 26 June 2019 at the latter's office and resulted in the formation of a Citizens' Technical Advisory Committee (CTAC) with three private engineers (Mr Patel as chairman of the committee, Dr VV Nori and myself), a faculty member each from VJTI and IIT Bombay, and the Chief Engineer (Bridges) from MCGM as member secretary. (https://www.moneylife.in/article/bmc-sets-up-new-advisory-panel-on-bridges/57556.html).

What follows is a brief account of the Committee's work and the lessons learnt from a very interesting experience of a PPP (public-private partnership) in unchartered territory. As a preamble, the incumbent Municipal Commissioner, Mr. Praveen Pardeshi deserves full credit to have set up the Committee against all odds. The position of the Municipal Commissioner of the Maximum City comes with a crown of thorns -- but Mr. Pardeshi appears to wear the crown stoically.

The objective of this account is to illustrate one among a myriad possibilities for constructive intervention by citizens' initiatives and, going forward, put in place a template for formal procedures to engage with authorities effectively to create a win-win situation for the establishment and the public at large.

Encounter with the Bridges Department

A kick-off meeting of the CTAC was held at the office of the chief engineer (CE) bridges on the 28th June which was attended by the chief engineer, deputy chief engineer and numerous executive and superintending engineers of the bridge department, and CTAC members from the private sector. The bridges department has seen many mergers and demergers in its chequered history. An independent department originally, it was merged with the department of roads and traffic in mid-November 2006 and was again carved out as a separate department in 2013.

Since then, the bridge department has had to deal with fatalities related to deficiencies or failures of - bridges on an annual basis and respond to angry citizens, politicians and face relentless media scrutiny. So there we were, sitting in a fledgling department (a six-year-old in the 132 year history of the mother MCGM) whose first chief engineer was presently in jail and two colleagues of the engineers seated across the table from us were still in custody. It is thus hardly surprising that the department would view any new external agency with suspicion. While the stated objectives of the CTAC were unarguably noble, it was foisted upon a department with frayed nerves. To them, CTAC was another nuisance to be dealt with.

The Hurdles

The department informed CTAC that it had been conducting a comprehensive structural audit program of 327 bridges under its purview since 2016 through three consultants. On further enquiry, it emerged that the department did not have standard operating procedures (and checklists) for conducting bridge audits and each consultant was conducting the audit based on individual capacity. Left to their devices, auditors simply tagged bridges which in their opinion were unfit for vehicular movement as "fit for demolition".

A more nuanced approach to bridge condition survey is called for, rather than a bipolar "good" or "fit for demolition" approach. Oftentimes, bridge life may be extended by simple retrofit measures. Bridge retrofit, wherever possible, can not only save capital expenditure, but also avoid undue inconvenience to citizens caused by extended route closures. Alternately, only a part of the bridge may need replacement. The foundations for example could be in good condition and only the superstructure may need to be replaced.

The department was not in possession of the original design documents, nor did it possess historical documentation of the repairs and modifications to each of the bridges, quite unlike the British legacy of auditing the bridges through its own in-house engineers and keeping a detailed repair and maintenance log for every bridge they built. Our first visit to the department left us with an uncomfortable feeling that the department was harried by the absence of systems, procedures, capacity-building programs and a credible database of its assets.

CTAC's Groundwork Begins

In the aftermath of the 14th March incident (the Himalaya bridge had passed the safety audit), the audit of all bridges had been repeated and 29 bridges were deemed to be unsafe and were thus tagged for demolition. Of these, fifteen had already been demolished prior to our meeting and the department was in a position to offer 10 bridges for review to the CTAC. Closure of some of these bridges had evoked a strong response from the community, so any small contribution to a quick resolution of the bridge closure issue would be of much value.

Subsequent to the meeting, CTAC commenced the exercise of reviewing the bridges. The objective of the CTAC was to inspect the bridges to see the possibility of temporarily opening the bridges to ease the travails of the public for about six months until a more long term solution was put in place. Audit reports for the bridges marked for inspection were shared by the department.

In the subsequent two weeks, CTAC conducted numerous site visits to five bridges at Juhu Tara, Oshiwara, Laxmi Baug at Ghatkbopar-Andheri Link Road, Krishna Kunj at Malad and the Dhobi Ghat bridge, along with BMC's executive engineer and/or deputy chief engineer.

Corrosion Pervades

All the bridges under review were minor bridges and showed a similar distress pattern -- significant corrosion of the bottom reinforcement bars of the bridge deck slab. There was some minor deformation observed at some bridges. It was not possible to observe any cracking as access to the underside of the bridge was not possible.

Drone photography was able to capture the corrosion of the reinforcement but not any cracks in the concrete. The deterioration has likely been caused by a combination of all or some of these factors- a) inadequate cover to the reinforcement bars at the time of construction of the bridge b) original concrete did not have adequate denseness and durability c) environment was highly aggressive/ corrosive/polluted d) Poor implementation of an inspection and maintenance program.

The CTAC was of the opinion that the bridges at Oshiwara and Juhu Tara did not show any noticeable distress at the piers and foundations. While reinforcement corrosion of the slab was evident in the photographs, CTAC did not believe that the bridge was in imminent danger of a sudden and brittle failure and suggested that the bridge be opened in a phased manner to light vehicles and BEST buses (but not trucks) almost immediately, after the removal of overburden load due to incremental topping over the years and after some other minor modifications were implemented. Bridge deformation was to be monitored.

Retrofit as the Right Strategy

Retrofit to the bridge at Laxmi Baug was already underway during CTAC's visit to the site. The retrofit strategy entailed providing additional steel girders supported on freshly raised outcrops of the supporting piers over the bridge slab and supporting a chequered plate ramp on steel joists, thus relieving the underlying concrete slab of any superimposed load of vehicular traffic. CTAC was in agreement with this retrofit strategy as it ticked all the right boxes for a good strengthening system. The retrofit was quick, clean (almost no concreting involved and the steel members could be cut to size and brought to site), reversible and had salvage value when the bridge would be demolished.

The Krishna Kunj bridge at Malad had been load tested and the testing agency had recommended allowing light vehicles (no trucks) to be plied over it. CTAC concurred with the decision. The Dhobi Ghat bridge had been forced open by residents and users at the time of CTAC's visit. The committee was of the opinion that while the bridge could be opened for light vehicular traffic, an entry barrier needed to be in place for disallowing truck movement.

CTAC cleared all of the five bridges inspected by them for light vehicular movement with minor or no modifications up till 11 July 2019, barely 14 days since its formation. The balance five bridges that were marked for demolition were not offered for inspection to CTAC as they had already been opened to light traffic.

MCGM in a Dilemma

The MCGM bridges department found itself in an awkward situation. Prior to CTAC's bridge inspection and recommendations, the department had received a divergent opinion from VJTI for the bridges at Juhu Tara and Oshiwara. The faculty member had recommended strengthening the deck slab of the bridge by laying a 300 mm reinforced concrete slab over the existing deck. The consultants in CTAC were not in favour of this solution and considered it an uncalled for expenditure of the state's resources - a waste of the public's time and the Corporation's money. In their opinion, during construction the additional concrete would add further deadweight to the underlying deck slab. There was no value being attained by providing this additional slab and its absence was no worse than its presence.  

No Records

A strong case was made for this solution by the faculty member and the bridges department, based on the deformations for these bridges obtained during load testing of the bridge. But ironically there was no report of the load tests (these are expensive tests) available with MCGM for any of the bridges.


The procedure of the purported test, based on oral accounts, involved the use of tubes and measuring water levels which in CTAC's opinion seemed to have been unnecessarily primitive when sophisticated instruments for measuring levels are available and a code --Indian Roads Congress IRC:SP:51-2015 "Guidelines for Load Testing of Bridges" specifies how load testing should be done. The testing records kept were incomplete and casual and no final report was submitted to the department. In such a situation, CTAC was unable to draw reliable conclusions about the overall safety (or lack of it) of the bridge from the load test. All that could be said was that if the bridge had sustained the load of a battery of 32 tonne trucks, followed by partial elastic recovery, the bridge could safely carry light-weight traffic, including buses but not trucks.


The MCGM bridges department demanded a safety guarantee from CTAC if its opinion was to be heeded. It was disingenuous of the bridges department to make a request as such since it had not issued a formal letter of appointment regarding the constitution of the Citizens Technical Advisory Committee and its terms of reference. (This was also the reason, I believe, why the faculty from IIT refused to participate in any of the proceedings of the CTAC).


CTAC was a voluntary initiative to enable the bridges department to identify the key issues and challenges with respect to safety of their bridges. It was not a body formed for formal structural audit commissioned by MCGM. Nevertheless, two of the CTAC members gave such a certification in writing. One would assume that the demand for such a certificate implies that if it is given, it will be accepted and acted upon by opening the bridge to traffic.

BMC Disregards but CTAC Persists

Despite receipt of the written assurance from two members of the CTAC in their personal capacity, the department went ahead with the faculty member's advice of providing an additional reinforced concrete slab of 300 mm at the Juhu Tara bridge. The CTAC was understandably upset with the decision. After a meeting with the municipal commissioner, a second visit to the Oshiwara bridge was organised and based on the visit, CTAC was able to impress upon the department that providing the 300 mm additional slab on the Oshiwara bridge was not necessary. Tens of lakhs of rupees would saved in the process, besides further months of inconvenience of the public. Let us see what actually happens.  

Recommendations

It would be very useful for the bridges department of MCGM to undertake a capacity building exercise for its team and its consultants' teams to ensure competency, consistency and credibility in the bridge inspection, audit and maintenance program. An institutionalised training program also helps in seamless induction of new engineers into the system.

The writer would like to acknowledge the pivotal role played by Moneylife Foundation and Sanjay Nirupam and Sucheta Dalal, especially, in enabling the entire endeavour.

Mr Shirish Patel and Dr V V Nori have contributed significantly to the writing of this report.

(Alpa Sheth is managing director of VMS Consultants Pvt Ltd, a structural engineering firm in Mumbai. Ms Sheth is co-founder and managing Trustee of Structural Engineers Forum of India -SEFI (www.sefindia.org) and is a member of many drafting groups of the Bureau of Indian Standards

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