If the Heavy Civil IC has been successfuly delivering mega projects to quality, safety and timelines, it has been largely thanks to our ability to provide ‘tailormade’ solutions to suit the specific requirements of our customers which presupposes a clear understanding of customer requirements and expectations. Often, the challenges we face at our various sites are unique, without precedent that calls for quick appreciation of ground realities, understanding the true nature of the issue at hand and thinking on one’s feet to evolve mitigation strategies. We, as a team, have been able to think out-of-the-box to overcome many of these challenges.

Innovations can be big or small but our focus, as a team, will always remain to constantly seek ways to enhance productivity, improve cycle times, reduce execution time, cut costs that will, at the end of the day, translate into superior operational efficiency and more satisfied customers.

INNOVATIONS THAT BRIDGE THE FUTURE

Achieving operational efficiency at Heavy Civil

Perhaps, the most defining aspect of the Heavy Civil IC has been, as the name suggests, constructing projects of huge size and scale and as projects become bigger and more complex, the need for best practices and more efficient construction methods to enhance overall efficiencies and complete projects within stipulated timelines is greater.

Introducing some chief enablers

Enabling structures are the lifeline of Heavy Civil projects, to build imposing and permanent structures that are interdependent, as their design and details govern that of permanent structures and vice versa. The construction methodology decided during the tender stage, can have major consequences if changed mid-way through the project. Right selection, effective planning, design and operation of enabling structures are imperatives for success.

Launching Girders: With precasting technologies dominating the construction industry, precast segment erection has formed the backbone of infrastructure projects that are more equipment intensive than labour driven. In this realm, the Launching Girder (LG) has assumed prime importance. Huge precast segments were erected in challenging projects like the Hyderabad Metro by purpose-made erection machines called ‘1st Gen LGs.’ These 2-lane LGs are designed considering sharp curvatures in the alignment, capable of achieving a cycle time of 3 days per segment and a lifting capacity of 520 MT. Other types of LGs deployed at the Hyderabad Metro project included the underslung, the movable winch and the hinged LGs, all improvements on the 2-lane LG. Hinged LGs are preferred in the confined spaces of congested cities as these can be scaled to erect spans ranging from 19 m to 31 m with 128 m Radius of Curvature and a lifting capacity of 450 MT to achieve cycle times of 6 days per span. “The Movable Winch LG was developed to address the sharp curvatures of Hyderabad’s roads,” elaborates T Vijayakumar, Head – CPMC, Heavy Civil, “that were designed to erect spans of 31 m and 34 m with a Radii of Curvature of 128.1 m and 150.2m respectively with a rear segment feeding provision. The Hyderabad Metro project holds the record for the highest productivity in India in the erection of box girder superstructures (15 spans / LG month) as published in www.ice.org.uk,” he mentions proudly,

The capability and productivity of LGs were further enhanced in the construction of Goa’s 3rd Mandovi Bridge with the design and development of the Twin Box Launching Gantry to leverage hydraulic power. Hydraulic circuit systems were developed and deployed to improve operations, such as the remote operated segment positioning system, semi-automated side shifting system, and the support shifting system with a lifting capacity of 1500 MT that helped achieve cycle times of 6-10 days per span compared to other launching girders and, as a competitor to international brands.

Bridge Builders: Segments weighing up to 65 MT can now be erected using winches for erection and hydraulic jacks for movement with the specially designed, semi-automatic Bridge Builders (BB) that have revolutionized ROB construction. ‘Weighing about 120 MT, a pair of BBs can erect straight segments as well those with sharp curvatures of up to 128 m radius,” explains TVK, “and with a lifting capacity of 60 MT, we can achieve a cycle time of 2 days per segment.” First engineered for the Hyderabad Metro, BB set a world record for the fastest segmental span erection at Mandovi Bridge and an Indian record by constructing a 30 m span of the Malakpet ROB in just 25 days. BBs have accelerated the progress of special bridge projects as well like the 3rd Narmada Bridge, 3rd Mandovi Bridge, the Barapullah Extra Dosed Bridge, and the Durgam Cheruvu Bridge. “BBs have positively impacted productivity, cost, delivery, safety, quality and improved cycle times,” vouches V R Saravanakumar, Project Manager, HMRL. 

Moving from 2D to 3D to improve productivity: Laying cables in extremely confined spaces is one of the biggest challenges for teams working on vessels and Pritam Bose (Construction Manager, Vizag Vessel III) and team had only about 15,000 of them to lay maintaining stringent quality norms without interfering with other adjacent elements like pipes, internal structures, equipment, etc. 

“It was a tedious process as we had to keep referring back time and again to the drawings and spec sheets to match them to the actual situation at site,” he explains. “Chances of errors were high as every change conducted, big or small had to be captured.”

By replacing all 2D auto cad drawings and spec sheets with a single 3D PDF, life has changed dramatically for Pritam. “It has improved our productivity, we enjoy better visualization, there is less rework, we are able to manage change better and, most importantly, it has improved our FTRC (First Time Right Clearance),” he grins happily.

Skill set mapping to specific categories: Based on spend trends over the past 3 years, 63 major categories have been identified and mapped with the skill sets of team members to ensure that the right person is assigned the right procurement as category specialist.

Creating healthy competition to improve performance: The PUGH Matrix decision making tool is one such idea that is handy when several parameters are not at par and it has paid rich dividends for the organization in the use of TBM at the Bengaluru Metro project.

Innovations at the front line

Operational Efficiency through Lean techniques: Lean Construction Methodology has sharpened day to day tracking, smoothened work planning, improved standards of house-keeping and reduced cycle time of activities for the Mumbai Metro UGC-07 project team. Value adding and non-value adding activities have been identified with efforts taken to eliminate nonvalue adding tasks. The lean tools implemented are the last planner system, work sampling, value stream mapping, 5S, BIM Big Room Meeting, WS, VSM and LBMS.

“The project won the 1st Prize for Lean Implementation at the ‘Lean Construction Training and Implementation Programme 2018’ organized jointly by IIT-M, IIT-B and ILCE (Institute for Lean Construction Excellence) after 9 months of continuous evaluation,” shares a proud Jayarama H, Project Director, MMRC UGC-07. The award was won against tough competition among 8 sites (3 from L&T Construction and 5 from other companies). 

P&M Innovations: The P&M team of the MMRC UGC-01 project innovated a ‘Spider Boom Placer,’ a smaller version of the boom placer with automatic boom extension and swinging operation. “When using conventional concrete pumps in concreting works, our main concern was the enormous amount of time taken and manpower required to fix pipeline works apart from the delay in clearing the concrete from the choked pipes,” points out Avdhesh Kumar Mishra, P&M – MMRC UGC-01. “For a mere INR 4 lakhs, we developed the Spider Boom Placer that is smaller, more economical than other boom placers commercially available with OEMs that carry a tag of approximately INR 40 Lakhs plus.”

With the hard rock ground strata at UGC-01 impeding excavation productivity, the P&M team innovated two solutions to address the issue. Rock Splitter: that works on the hydraulic principle and depending on the rock strength, applies 60-100 MT load on the wedge which when inserted into the pre-drilled hole of suitable diameter, splits the rock which is then easily removed by excavators. Rock Buster: is a compact and user-friendly hydraulic device in which the drilled holes in rock are expanded and pushed outwards towards free face by applying 70-150 MT load directly on the rock surface.

“Since the size of projects we execute are so huge, the challenges we face are just as huge that call for innovative and out-of-the-box thinking at almost every step,” says SVD. “In fact, our very survival depends on our ability to stay ahead of the curve and we are committed to do so,” he sums up confidently.

4 HOURS TO BUILD A RAILWAY BRIDGE OVER FOUR ‘LIVE’ RAILWAY LINES

A milestone for L&T; a’first’ for the Indian Railways

On a cold and foggy night in New Delhi on January 26th, when the country was still awake to welcome India’s 71st Republic Day, two L&T teams, one from the WDFCC CTP 15 C project of nuclear & Special Bridges BU, Heavy Civil IC led by Project Manager, M Kannan and the Special Projects & Construction Methods (SPCM) team, attached to Divisional Coporate were in the last stages of preparations to launch one of the two steel griders weighing 160 MT across a 48.5 m span over four ‘live’ lines on the busy New Delhi-Mathura sector, at Asoati in Palwal near Faridabad.

“Normally, we would have used the ‘push launch’ method for such an erection,” points out V Kasiraja, General Manager, SPCM who was one of the prime movers of this operation. “We would have done it in stages with supports, a long-drawn process that would have taken at least a month, and when the work was in progress, the trains would have to move slowly which was not acceptable to the Indian Railways.” That prompted the team to develop an innovative method to launch the long span girders from one end of the RFO using crawler cranes in tandem. “The bridges were handled below the centre of gravity since the cross girder of the bottom chord was stronger, the rigging gears were designed accordingly to ensure stability. For us it was a normal erection but for them,” chuckles Kasiraja, “Rapid bridge construction.”

Preparing the ground for launch

Preparation is key to the success of such an operation. “Tougher than the actual erection was convincing the authorities at the Indian Railways that what we were suggesting was feasible because they had not seen anything like this before,” shares Kasiraja. “In fact, our approval sheet carries 30 signatures of various railway officials!” To address their reservations, a mock lift was arranged and executed post which the teams were given the go ahead.

Their first task was to literally prepare the ground for the launch. With paddy fields adjoining the tracks where the super heavy-duty crawler cranes had to be positioned, the project team had to ‘borrow’ the land from the owners, prepare hard stands and lay steel mats on which the cranes were placed. Although only two cranes were used for the erection, another 3 were on standby.

All the elements of the bridge were first assembled on the ground that comprised of two Open Web Structural Steel Girders of 48.5 m span with 7.0 m x 10.9 m cross sections weighing 160 MT each. After assembly, they were torqued, painted and then with the cranes and the super lift counterweights ready, the team waited for the go ahead from the railway authorities to commence operations.

Get. Set. Push …

They received the green signal at 12.40 am and had a tight 4-hour window till 4.40 am to complete the erection. It was therefore all systems go.

The bridge was first lifted from the assembly bed with two 600 MT capacity Demag CC2800-1 cranes. While the rear crane marched the entire length of the bridge, the front crane marched only till the railway line barricading and since further movement was not possible, super lift counterweights of 250 MT were added to enhance the capacity before lowering and reaching the other end (radius of 40 m). 

The erection was successfully completed almost an hour before the cut off time to the delight of the railway officials in attendance, watching the entire exercise with bated breath, that included Mr. Anurag Sachan, Managing Director, DFCCIL, who was effusive in his praise of the operation in a letter to Mr. S N Subrahmanyan, CEO & Managing Director, L&T. “The complete launching activity was executed in a best-of-class manner that is chiefly attributable to the meticulous planning and coordination between DFCCIL, Indian Railways, PMC-2R and L&T,” he wrote, further expressing his appreciation of the team’s precautionary and emergency standby arrangements and for maintaining the highest levels of safety throughout the operation.

Having perfected the act, the teams launched the second girder on the night of January 28th with equal alacrity, efficiency and success. For Kasiraja and team, the success is even more satisfying because as Kannan remarks with pride, “our method has now been adopted by the Indian Railways as a standard operating procedure for all such erections!”

RIYADH METRO –
BULDING VIADUCTS EFFICIENTLY!

6 lines, 176 kms long Riyadh Metro network is being built by some of the biggest names in the global construction industry. 41 km of line 3 is being constructed by L&T as a major partner in the ArRiyadh New Mobility consortium. Running from west to east, 25.7 km of the line is elevated,with underground sections in the middle and the remaining portion at grade. The line features 20 stations, 2 iconic stations and 2 depots at either end.

Shaping the Viaduct: The viaduct has been designed to optimally accommodate a double track and a maintenance/emergency steel walkway on both sides that also carry the cables trays throughout the route. The structural arrangement is a 3 celled box girder with a sleek, aerodynamic fish belly bottom. For greater efficiency, the entire elevated portion is precast, executed as precast segmental decks with match-cast segments. The deck is supported over a single pier located over the central median for most of the stretches. There are over portals straddling the road when the alignment is away from the central median.

Standardisation is key: Though there are varying requirements for changing the superstructure, the profile is standardised to fit the basic fish belly shape to give a uniform band across the entire viaduct.

To accommodate road crossings of up to 50 m, 3-span continuous hyperstatic superstructures have been adopted with the same standard profile. A similar continuous superstructure arrangement is used to deal with sharp curvatures of up to 150 m and steep gradients of up to 5.5%. For larger road crossing spans (maximum is 95 m), the central cell depth alone is increased gradually from the centre to the supports, maintaining the end cell shape and the uniform band effect and constructed using balanced cantilever construction techniques.

Enter the versatile Universal Launching Girder (ULG): Considering the variety of the construction involved – typical, continuous and stations spans – and the tight schedule, the team decided to deploy 7 ULGs that were versatile enough to handle the different size of spans, dimensions and weights. To use the same launching gantry, continuous spans were carried out in two phases – first the mini cantilever portions near the central piers and then the infills and end spans. The station segments were different, 17 m in width (wider because of the innovative design), 3 m long and weighing up to 130 tons. As the station and continuous spans were designed with precast segments to be erected by the ULG, the erection of the viaduct and station spans / continuous spans could continue uninterrupted without dismantling and re-erecting the ULG near stations. 

Challenges & solutions

There were challenges for superstructure erection pertaining to terrain, alignment and traffic diversions but these were pre-empted and considered when finalizing the specifications for the ULG with respect to loads and the design.

Speeding across an expressway: The ULG successfully launched a particularly challenging span with a sharp curvature of 150 m radius and a high gradient of 5.6% over the Jeddah Road, one of the busiest expressways, with only a small window of time open for erection. Not once but twice across the expressway to accommodate a station across the other side of expressway.

“Meticulous planning, precise detailing of construction stages and design enabling structures helped us to deliver,” explains Design Head, K. Senthilnathan (KSN). “There were about 58 stages (584 steps) required to complete this complex erection activity and each stage was analysed, and detailed drawings prepared. Our team from the technical office monitored the stages at site to ensure that the erection was safely carried out across the expressway with heavy traffic running all the while below.”

For G. Vinod, Head Elevated Section, this was the first major challenge to prove the efficacy of the launching girders of handling erection over a live expressway within a very restricted four hour window per night. “We had to move the elements and lift them,” he shares enthusiastically, “but this is a major milestone receiving continuous accolades from both client and consultants.”

Straddling the hurdle: MVS Rao, Viaduct Head, recalls that a huge challenge for his team was to lift the ULG above the architectural piers supporting the sprawling iconic landmark station. KSN points out, “Designing these piers to support the launching girder was both costly and risky as the height of the piers from the station basement is approximately 20 m plus there were the sharp 150 m curvatures of the approach spans to consider that required special tie- downs.” Since the station platform was not being erected by a launching girder, the original plan was to dismantle and re-erect the LG at location that would interrupt work on the station. “Literally, thinking on our feet, we devised a new plan to advance the construction of superstructure as a tie element by integrating the inclined pier to provide a robust structural connection by introducing a closed frame action,” recounts G Vinod. The entire system was conceptualized and devised in-house by the technical department and the detailed design verification was carried out by the design consultant, without any major modification to the available design and in very quick time. “Finally, the LG was moved over the station in 3 days,” says an extremely satisfied G. Vinod, “and we achieved it with detailed construction method planning, immense design support and perfect logistic coordination between the 5 stakeholders involved.”

“Client appreciation for Line-3 Viaduct is a testimony of our team efforts,” T. Srinivasan, Head Riyadh Metro summarises, “and credit goes to the entire team for their efforts to leave a legacy viaduct structure in Riyadh and build L&T’s brand image in the Kingdom of Saudi Arabia.”