Bandra Worli sea link

Bandra-Worli Sea Link

Lessons to learn from

The Bandra-Worli Sea Link presents an interesting case-study of infrastructure planning and management issues, in line with our discussion on the Montreal Olympic Stadium. The sea-link was originally conceived of in 1960s, but received a green signal only in 1999, after studies were conducted by the Central Road Research Institute and the Mumbai Metropolitan Region Development Authority (MMRDA). The Maharashtra State Road Development Corporation (MSRDC) was appointed as the nodal agency for the project in 1999. The MSRDC awarded the project to the Hindustan Construction Company (HCC), but only to see a series of failure in meeting deadlines. The initial deadline was December 2004 which was later revised to December 2007 and then to December 2008. Actual work, however, did not commence until January 2005 when the Supreme Court gave the project go-ahead. The consequences of haphazard planning and scheduling, as was evident in the Montreal case, are reflected in this example as well.

The MSRDC changed consultants in 2003 and gave entry to Egypt-based Dar Consultants. The new party brought in tremendous design changes which escalated the costs by four times (Rs 4.4 billion to Rs 16.34 billion). HCC is said to have lost about Rs 4 billion due to these changes. Thus we see the role of designing and its crucial place in the overall implementation of an infrastructure project.

In April 2009, days before the completion of the project, three sets of sub-contractors threatened to pull out due to issues with the consultants. One of them, the Roman Tarmant Ltd., was about to obtain a contract for Polymer Modified Bitumen (PMB) surfacing to provide a water-proof road. However, the company backed out due to unreasonable conditions on warranty period. The wide spectrum of players involved in an infrastructure project and the corresponding human management that the size of such projects calls for is evident in this case.

A part of the rise in costs was due to the interests on borrowings and payment to the Municipal Corporation of Greater Mumbai for a casting yard, an instance that shows how economic factors can equally inflect a project just as any other. Also to be noted is the fact that around 4000 workers and 150 engineers from India as well as China, Egypt, Canada, Switzerland and Britain are said to have participated in the project, which would have demanded micro-level cultural integration, a pointed that was highlighted in the class.

A few local issues like environmental concerns and issues pertaining to the fishermen, also surfaced during construction, which, though parochial, could have impeded the completion of the project. The Bandra-Worli sea-link, however, managed to brush such concerns aside with active political support from the state. To epilogue, this project presents many of the nuances involved in infrastructure planning and shows the amount of meticulousness that the task calls for.

Sources:
Indian Infrastructure, July 2009
"Bandra-Worli Sea Link: A Traveller's Delight", The Economic Times, June 30, 2009
(http://economictimes.indiatimes.com/News/Economy/Infrastructure/Bandra-Worli-sea-link-A-travellers-delight-/articleshow/4718082.cms)
Official Website (http://www.bandraworlisealink.com/)

MIVAN formwork.

SYSTEM OF PRECAST CONSTRUCTION

An engineered system of building construction, namely “3-S” system was developed by B.G.SHIRKE CONSTRUCTION TECH LTD., for achieving, speed, strength, safety and economy in construction practices. The system involves structural elements such as pre-cast hollow column shells pre-cast concrete beams, light weighed reinforced cellular autoclaved concrete slabs for floor and roofs constituting the basic structural formwork. The “3-S” system involves activities for construction of building such as:

I. Cast in-situ sub-structure including foundations, stem columns, plinth beams, plinth masonry.

II. Erection of partial pre-cast components, jointing of these components using cast in-situ concrete with appropriate reinforcement.

III. Lying of reinforced cast in-situ screed over slab panels, construction of panels, construction of walling, flooring, plastering, water proofing etc.

Achieving the “3-S” system in the MIVAN formwork is quite easy. MIVAN formwork has got the unsurpassed speed of construction due to saving time for required time in masonry and plastering. The strength of raw aluminium is very less but when alloyed with other materials prove to be strong enough to use as a formwork . To ensure safety in the site, an integrated safety/ working platform is developed which ensures labor safety during erection and striking of the formwork. Economy is also one of the main factors of any system. The MIVAN formwork proves to cost efficient as it can be used efficiently for 250 times.

Present Technologies Available in INDIA

Some of the advanced technologies of formwork catering to the speed of construction are given below:

To name a few:-

1) The Prefabrication Technology

The Pre-cast concrete elements in roofs, floors and in walls have become more common as these eliminate shuttering; centering & plastering labor and saves material cost.

Prefabricated Technology (Raymond, 2001)

2) Tunnel Formwork Technology

It is a technology constructing large no of housing within short time using steel forms to construct walls & slabs in one continuous pour.

Tunnel formwork (Raymond, 2001)

3) Outinard Technology

Outinard’s superior engineering, the use of high quality steel and High Performance quality control result in a vastly superior Wall Form system.

Outinard Technology (Raymond, 2001)

4) Mascon Technology

The Mascon Construction System is a system for forming the cast in-place concrete structure of a building. It is also a system for scheduling and controlling the work of other construction trades such as; steel reinforcement, concrete placement, and mechanical and electrical trades.

Mascon Technology. (Raymond, 2001)

Computer Aided Planning for Tunnel Construction

Tunnels are subterranean conveyance systems. Historically tunnelling projects have suffered significant cost and time
overrun on account of variation in geological formation. Variation in strata may lead to various problems like tunnel
caving in, water seepage etc. An attempt has been made to extend the Q-system of rock mass classification for reliable
prediction of these tunnelling problems. For the purpose tunnelling problems have been identified and classified. A
computer tool has been developed to aid the process. Also simulation as an aid for time planning while tunnelling under
such varying geological conditions has been investigated. Reliable estimates of tunnelling problems and effect of
geological variations on the project schedule will help the project management in informed decision making as regards
issues like resource requirement. This paper describes the compilation and classification of tunnelling problems,
matching problems to the Q-system parameters and the simulation model developed.
Keywords: Tunnelling projects; Geological strata variation; Rock mass classification; Q-system; Project management
INTRODUCTION
Tunnels are used in the transportation sector for conveyance
of highway and railway traffic. They also serve as a means of
conveyance of water in irrigation and hydroelectric power
projects. During construction of tunnels variation of strata is
often encountered. This poses various problems in tunnelling.
Also, the decision regarding the support system required for
various strata is critical to ensure trouble free construction. As
the geological formation for each tunnel project is usually
very different and all scientific studies are carried on a project
specific basis, tunnelling in a new formation remains an art
than a science wherein the designers rely on intuition and
previous experience to effectively solve problems.
The Q-system is a system of rock mass classification1. This
system is essentially used in determining the support system
requirement for tunnelling under the prevalent geological
condition. The parameters of the Q-system are representative
of the geological conditions of the project. These parameters
have been used in predicting the problems likely to be faced in
tunnelling.
Manual calculation for Q-system is very tedious and time consuming.
This is significant considering the fact that the calculations
have to be done for every drill and blast cycle of the
tunnel construction, which may run into thousands for each
project. Thus a computer tool has been developed to aid in the
process which will save both time and effort.
H I Bidaiah is with International Metro Civil Contractors, 8 Jantar Mantar
Road, near Connanght Place, New Delhi 110 001; Dr K Varghese is with
Building Technology and Construction Management Division, Department
of Civil Engineering, Indian Institute of Technology, Madras, Chennai
600 036 while A N Mazumdar is with L&T-ECC Construction Division,
Mount Poonamallee Road, Manapakkam, PO Box 979, Chennai 600 089.
This paper was received on August 13, 2001. Written discussion on the paper
will be entertained till July 31, 2003.
Tunnels are typically constructed either using the drill and
blast method or by using tunnel boring machines. The
tunnelling operation is a repetitive process wherein the same
activities are repeated in each successive cycle. Also, it is
common practice to open up more than one face of a tunnel
for excavation, so that the project can be expedited. Thus, the
various activities fight for the same resource. This makes
resource allocation an important issue to be considered in
tunneling operations. This also influences the project
schedule.
As mentioned earlier one of the major uncertainties faced
during tunnelling is that of variation of strata. Initial
geological investigation gives a fair idea of the type of rock
that might be encountered. But uncertainty prevails and
makes time planning all the more difficult. Simulation can be
used as an effective tool to aid in planning as regards issues like
resource requirements while working under varying
geological conditions.
Q-SYSTEM
The Q-system1 of rock mass classification was developed in
Norway in 1974 by Barton, Lien, and Lunde all of the
Norwegian Geotechnical Institute. The Q-system is based on
a numerical assessment of the rock mass quality using six
different parameters
o Rock Quality Designation;
o Number of joint sets;
o Roughness of the most unfavourable joint or
discontinuity;
o Degree of alteration or filling along the weakest joint;
o Water inflow; and
o Stress condition.

Construction Planning

The development of a construction plan is very much analogous to the development of a good facility design. The planner must weigh the costs and reliability of different options while at the same time insuring technical feasibility. Construction planning is more difficult in some ways since the building process is dynamic as the site and the physical facility change over time as construction proceeds. On the other hand, construction operations tend to be fairly standard from one project to another, whereas structural or foundation details might differ considerably from one facility to another.

Forming a good construction plan is an exceptionally challenging problem. There are numerous possible plans available for any given project. While past experience is a good guide to construction planning, each project is likely to have special problems or opportunities that may require considerable ingenuity and creativity to overcome or exploit. Unfortunately, it is quite difficult to provide direct guidance concerning general procedures or strategies to form good plans in all circumstances. There are some recommendations or issues that can be addressed to describe the characteristics of good plans, but this does not necessarily tell a planner how to discover a good plan. However, as in the design process, strategies of decomposition in which planning is divided into subproblems and hierarchical planning in which general activities are repeatably subdivided into more specific tasks can be readily adopted in many cases.

From the standpoint of construction contractors or the construction divisions of large firms, the planning process for construction projects consists of three stages that take place between the moment in which a planner starts the plan for the construction of a facility to the moment in which the evaluation of the final output of the construction process is finished.

The estimate stage involves the development of a cost and duration estimate for the construction of a facility as part of the proposal of a contractor to an owner. It is the stage in which assumptions of resource commitment to the necessary activities to build the facility are made by a planner. A careful and thorough analysis of different conditions imposed by the construction project design and by site characteristics are taken into consideration to determine the best estimate. The success of a contractor depends upon this estimate, not only to obtain a job but also to construct the facility with the highest profit. The planner has to look for the time-cost combination that will allow the contractor to be successful in his commitment. The result of a high estimate would be to lose the job, and the result of a low estimate could be to win the job, but to lose money in the construction process. When changes are done, they should improve the estimate, taking into account not only present effects, but also future outcomes of succeeding activities. It is very seldom the case in which the output of the construction process exactly echoes the estimate offered to the owner.

In the monitoring and control stage of the construction process, the construction manager has to keep constant track of both activities' durations and ongoing costs. It is misleading to think that if the construction of the facility is on schedule or ahead of schedule, the cost will also be on the estimate or below the estimate, especially if several changes are made. Constant evaluation is necessary until the construction of the facility is complete. When work is finished in the construction process, and information about it is provided to the planner, the third stage of the planning process can begin.

The evaluation stage is the one in which results of the construction process are matched against the estimate. A planner deals with this uncertainty during the estimate stage. Only when the outcome of the construction process is known is he/she able to evaluate the validity of the estimate. It is in this last stage of the planning process that he or she determines if the assumptions were correct. If they were not or if new constraints emerge, he/she should introduce corresponding adjustments in future planning.

Earth Building

Mudbrick, also referred to by the Spanish name of 'Adobe' which means mud or puddled earth, generally refers to the technique of building with sun-dried mud blocks in either load bearing or non load bearing construction. Mudbricks are becoming increasingly commercially available in a range of stabilised and non stabilised bricks.

Mudbrick has several advantages over conventional fired clay or concrete masonry. The advantages include:

• Low in embodied energy
• Utilisation of natural resources and minimal use of manufactured products
• Good sound absorption characteristics
• High thermal mass
• A claimed ability to "breath"
• Suited to a wide range of soils
• Easily manufactured and worked
• Flexibility in design/colour/surface finishes
• Insulation properties similar to those of concrete or brickwork

Mudbricks are typically 250 mm wide x 125 mm high x 375 mm long and normally made from earth with a clay content of 50 to 80% with the remainder comprising a grading of sand, silt or gravel. Kaolin clays are the preferred clay types due to their non expansion characteristics. Stabilising the mudbrick with straw or other fibres is sometimes employed where the soil mix displays excessive shrinkage behaviour. Cement and bitumen stabilising is also used with the latter particularly effective in waterproofing.

From an engineering viewpoint, mudbricks typically have compressive strengths of around 1 to 2 MPa and need to posses a demonstrated resistance to erosion and cracking before being accepted for construction. Mortar for mudbrick laying is either a traditional sand/cement mortar or a fine aggregate soil mortar preferably made from the same parent material as the mudbrick units.

Finishing of mudbrick walls can be undertaken with a variety of techniques ranging from as constructed to a simple "bagged" finish to a full set earth render. Linseed oil is commonly used to seal the exterior of as constructed mudbrick.

Value Engineering

Value engineering may be broadly defined as an organized approach in identifying unnecessary costs in design and construction and in soliciting or proposing alternative design or construction technology to reduce costs without sacrificing quality or performance requirements. It usually involves the steps of gathering pertinent information, searching for creative ideas, evaluating the promising alternatives, and proposing a more cost effective alternative. This approach is usually applied at the beginning of the construction phase of the project life cycle.

The use of value engineering in the public sector of construction has been fostered by legislation and government regulation, but the approach has not been widely adopted in the private sector of construction. One explanation may lie in the difference in practice of engineering design services in the public and private sectors. In the public sector, the fee for design services is tightly monitored against the "market price," or may even be based on the lowest bid for service. Such a practice in setting professional fees encourages the design professionals to adopt known and tried designs and construction technologies without giving much thought to alternatives that are innovative but risky. Contractors are willing to examine such alternatives when offered incentives for sharing the savings by owners. In the private sector, the owner has the freedom to offer such incentives to design professionals as well as the contractors without being concerned about the appearance of favoritism in engaging professional services.

Another source of cost savings from value engineering is the ability of contractors to take advantage of proprietary or unusual techniques and knowledge specific to the contractor's firm. For example, a contractor may have much more experience with a particular method of tunneling that is not specified in the original design and, because of this experience, the alternative method may be less expensive. In advance of a bidding competition, a design professional does not know which contractor will undertake the construction of a facility. Once a particular contractor is chosen, then modifications to the construction technology or design may take advantage of peculiar advantages of the contractor's organization.

As a final source of savings in value engineering, the contractor may offer genuine new design or construction insights which have escaped the attention of the design professional even if the latter is not restrained by the fee structure to explore more alternatives. If the expertise of the contractor can be utilized, of course, the best time to employ it is during the planning and design phase of the project life cycle. That is why professional construction management or integrated design/construction are often preferred by private owners.

Tower Cranes for civil engg projects.

Parts of a Tower Crane

All tower cranes consist of the same basic parts:

• The base is bolted to a large concrete pad that supports the crane.
• The base connects to the mast (or tower), which gives the tower crane its height.
• Attached to the top of the mast is the slewing unit -- the gear and motor -- that allows the crane to rotate:

On top of the slewing unit are three parts:

• The long horizontal jib (or working arm), which is the portion of the crane that carries the load. A trolley runs along the jib to move the load in and out from the crane's center:

• The shorter horizontal machinery arm, which contains the crane's motors and electronics as well as the large concrete counter weights:

• The operator's cab:

The machinery arm contains the motor that lifts the load, along with the control electronics that drive it and the cable drum, as shown here:

The motors that drive the slewing unit are located above the unit's large gear: