New Generation Pre-fabricated quick launch bridges can play a major role in augmenting infrastructure especially in difficult terrains in places like Uttarakhand, Himachal Pradesh, Jammu & Kashmir and North East States as well as forward defense areas.
India has challenging ground conditions in places like Uttarakhand, Himachal ,,Jammu & Kashmir or the northern and eastern parts of the country which are prone to landslides and difficult terrain.In these areas, the pre-engineered and quick launch bridges can be of big help.
Innovative technique of building large number of bridges in short span of time at low cost in the sector is fast picking up across the world. In countries like the United States of America, China, Japan, France, Germany, Netherlands and Belgium, this technique of building bridges is widely used. Focus should be given to using modern techniques for improvement of conventional bridges in the country which form the majority.
The Indian road network consists of more than one lakh bridges including about 16,000 on National Highways . Evolution of technologies that facilitate quick construction of bridges on a running roads are the need of the hour in the country .
The New Generation Quick Launch Bridges are expensive is a myth, and needs to be corrected. The Infra Sector can take advantage of these Bridges in India. The rest of the world is already doing so. In emergencies and where we need to save time, these New Generation Bridges are far superior and more cost effective than the presently used Bailey Bridges. Decision makers and users must see beyond the L-1 approach in finding solutions, and compare the advantages in a more holistic manner. They will then realize the savingsare much more than the small price difference at purchase. For this one needs to understand the technical aspects and the long term advantages clearly.
The Bailey Bridge stocked by most government organizations including the Public Works Department (PWD) , is primarily foremergencies. Recently the foot over-bridge constructed at Elphinstone Station, Mumbai was in the news. The Army Engineers received acclaim for the speedy work. Such Quick launch Bridges are handy when there is pressure of time such as during disasters when key areas are cut off or to speed up a project where time is adversely affecting the cost of the project.They are also handy for projects indifficult terrain, where approach to the work site is critical and so the need for its extensive use and stocking.
These bridges are used as temporary bridges as they are easily launched and de-launched and can be reused. They are versatile being modular and easy to carry, and can be launched with restricted construction space. But the Bailey Bridge which is of Second World War vintage has its limitations.
The limitations of the Bailey Bridge are that it was designed as a temporary or at best a semi-permanent bridge with a life of 20 years. The road way is limited to a maximum of 4.2m allowing single lane only. For spans up to 60m it can be constructed to Load Class of 30 T whereas National Highways (NHs) require 70 R and Single wheeled load trains up to 100 Tons with a minimum roadway of 5.3m. The Bailey is grossly inadequate and is used with load restrictions, choking the NHs, restricting both traffic flow and loads. This effects optimal utilization of double lane NHs, leading to higher transportation costs, larger carbon-footprint and lower safety standards. Many of these bridges have collapsed due to overloading, not meeting the aspirations of the locals who want to utilize the NHs to its full capacity to derive commercial benefits and fast track development activities.Yet the only option we seem to have is to launch the same bridge where there is an emergency and hope for the best.
In anemergency situation due to collapse of a 36m span Bailey Bridge in Jun 2015 at Sonprayag,causing the route to Kedernath to be cut off, a bold decision was taken to launch a permanent bridge in time for the Yatra to the shrine – a longer span, Class 70 R ACROW Bridge. This proved to be a permanent and more cost effective solution and return on the investment accrued the same year, allowing the Yatra to take place in Apr 16. The related commercial activity for the locals was a boon and many times beyond the cost of the bridge. The advantages of the ACROW Bridge are many fold. It is a permanent bridge launched quickly.
Quick launch bridges have a life of 75-100 years; the galvanized steel is good for 75 years before it even starts to deteriorate. It can be launched to road widths varying from 3.7m to 14.6m, allowing 4-5 lanes as required. It allows loads up to IRC 70 R or even 150 MLC as used by the US Army. It has also been used as Rail Bridges and a number of other applications. With all the advantages of a permanent bridge, the added ability to launch or de-launch quickly allows it to be used multiple times even as a temporary bridge. All this has to be factored when we compare costs with other bridges. Otherwise it will be a flawed comparison as between oranges and apples.
The prominent factors that need to be compared for cost are:-
Per Sq/m cost is more realistic than absolute cost. This will allow for lanes wider than the maximum of the Bailey Bridge (itsmaximum width, 4.2m is below specifications for 70 R).
Live Load Factor. When a bridge allows a 100 T and is compared with a bridge that can take only 30 Tons, logically the cost per ton of load is a more aptcomparison.
Life Cycle Cost includes the initial cost with the maintenance cost, computed to give a cost on annualbasis. When comparing a temporary bridge of 20 years life with a Permanent Bridge with nearly zero maintenance, the initial costs will be grossly misleading. The long term savings will be huge, almost three times.
Commercial Advantage. This is the advantage of Quick launch in say 3-6months depending on the time for preparing abutments and to move the equipment to site. When compared against 1-2 years for a regular bridges, may be even 3 years for spans of 60m, the cascading effect on commercial activity is pertinent. Any delay holds up commercial activity and affects the morale of the locals. These are normally overlooked, as it is difficult to quantify. Frankly it could be more than 20-30 times the cost of the bridge. A decision maker has to account for this aspect; otherwise it will not be in sync with local needs. This has carried on long enough and needs to change.
The New Generation Quick Launch Bridges can easily prove to be cost effective in the long run, vis-à-vis the existing solution for emergencies. There is need to stock these bridges so that they can be delivered and erected within a month in an emergency. The bridge would be to IRC standards, safe and permanent. It can also be used for routine construction where time saving will offset any difference in initial cost – an approach that requires a value for time and the related effect on commercial activity and the delay in giving respite to locals. For a concessionaire early completion and collecting toll and avoiding penalty could be a factor to consider such bridges. It is actually a win-win for both the concessionaire and the authorities in such cases.
Another use is the replacement of existing bridges with minimum delay, either to upgrade from single lane to double lane bridges or to change a bridge because the existing bridge is weak,by resorting only to temporary detours and using the same site. With the extensive survey of bridges undertaken by the MORTH, the need for this will grow. It is time we looked at workable options to save time and avoid inconvenience to the public.
Let us be more realistic in comparing costs and take advantage of good technology. Once the need is recognized, demand will grow and such bridges can be ‘Make in India’in the near future. Ultimately, bridge solutions have to be simplewith the right priorities. We need to demand better, safer bridges and fast construction,shaking off the “Chalta Hai” attitude of accepting unsafe bridges that also lead to underutilization of National Highways s.
article by K. K. Kapila
