01 May 2019
Complexities in bridge construction
The success of a bridge project depends on the management of various complex and interlinked issues such as timely decisions, robust risk assessment and its mitigation, timely approvals of design and drawings, effective mobilisation of men and machinery, material planning, implementation of right construction methods, project and financial management, prompt and timely troubleshooting, and optimal and effective usage of resources. While all these factors carry inherent complexities, there could be more issues that are technical and administrative in nature. SV Desai, Executive Vice-President & Head - Heavy Civil Infrastructure IC, L&T Construction, elaborates....
- Availability of RoW and environmental clearances can eventually determine whether a contractor is able to deliver a project. Some L&T projects like Delhi’s Barapullah Bridge, Mandovi Bridge in Panaji, Goa, Khulna Mongla Bridge in Bangladesh and even Hyderabad’s Durgam Cheruvu Bridge have suffered initial delays owing to non-availability of RoW. A more recent example is the Mumbai Coastal Road project, stalled because of public agitations and environmental issues. A mechanism should be put in place by the respective state and central ministries to eliminate delays on account of these two factors.
- Non-availability of skilled labour and execution staff is another pressing issue. The Government has set up a Skills Development Council to encourage industries to develop skills and create a pool of trained indigenous workforce. L&T has established eight Construction Skills Training Institutes across India to impart training in various aspects of construction and improve productivity. Development of frontline supervisors is another initiative by the company to train fresh engineers in supervisory roles by exposing them to various aspects of construction. Despite all these efforts, owing to the boom in the construction industry, contractors are feeling the acute shortfall of skilled workforce, resulting in delays in project execution.
- Construction challenges could be several, starting with the construction of the foundation of a bridge that depends on the type (open, pile, well, or any other), soil strata, machineries deployed and other logistic issues. In the case of the third Mandovi Bridge, special engineering techniques were adopted to counter the rock boulders left over from the construction of the two earlier bridges. Similar surprises in the foundation media can delay construction if not addressed adequately at the design stage. The next critical step is the construction of the superstructure that involves transport of heavy precast elements through busy roads/waterways, and positioning and erecting them at site. This issue must be addressed with correct design and construction technology right at the planning stage to avoid mishaps, delays and consequent cost escalation.
- Changes: Complexities could arise from changes in the alignment of the bridge. Unchartered utilities like underground pipe lines, gas lines, cables and high-tension electrical lines are most commonly encountered while constructing bridges. Shifting or relocating these utilities requires approvals from government bodies resulting in undue delay. In several instances, bridges have to be redesigned as some the utilities cannot be re-routed or disconnected.
- Adverse and challenging terrain can impact delivery. L&T’s project to construct the Kachchi Dargah Bridge in Patna across the Ganga has often been disrupted owing to frequent and sudden floods. The construction of the Panvel Nadi viaduct in Maharashtra for Konkan Railways, one of Asia’s tallest viaducts, involved the use of the innovative incremental push method across a deep gorge. Numerous such instances have been faced by L&T at various bridge projects across the country.