V. B. SOOD
Director (B&S) SB-II, RDSO, Indian Railways
Steel bridges have been constructed in India since mid-nineteenth century and their performance has been outstanding. Looking at the history, the future of steel bridges in India looks quite bright. Today, I see more awareness amongst the designers and users regarding steel as a modern material of construction.
With aesthetics being emphasized in steel construction such as in PEB structures, and the airport structures constructed using hollow steel sections, steel is being looked at with renewed interest and fascination. That steel is a greener material of construction as compared with other alternatives is also one of the factors that is driving acceptability of steel as structural material.
Steel is a very traditional product and many a box-shaped bridges with not-so-great aesthetics and rampant corrosion are seen all over India. This was a bad publicity for steel as a construction material, though, the steel still impressed people with its residual strength and performance even under such bad conditions. But, the modern-day bridges are in a different class altogether. These bridges are not only strong, but, also beautiful.
With increasing use of high corrosion resistant coatings, the image of steel structures is undergoing a change. For example, Bogibeel Bridge being constructed over river Brahmaputra near Dibrugarh in Assam which is the first fully welded truss on Indian Railways, has very neat details that underline the aesthetics and powers of modern day bridges. Steel has allowed us to go for longer spans, and the railway lines being constructed in the hilly terrains are being facilitated by steel construction to a large extent. To me, this beauty in steel is the real revolution in construction of modern-day bridges.
I have been involved with steel projects since last 15 years or so: in all aspects like inspections, maintenance, launching of girders and design of bridges. The most exciting project that I have been involved with, was in year 2002, when we decided to replace all ten girders of a bridge in a single six-hour duration, for a work that normally is done in ten blocks of three-hours each, spread over two months. The planning, arrangements and great execution of this highly complex work was highly satisfying.
Other than this, I was instrumental in changing the technology of rivets with High Strength Friction Grip bolts on Indian Railways. The satisfaction came from the fact that changing traditions is not easy in Indian Railways, and I had to go deep into the subject to be able to convince the decision-makers about the methodology to ensure that bolts can perform as envisaged, and this process would benefit the Indian Railways immensely. The hard wok put in for this project was highly satisfying and today, in Indian Railways, all steel connections in field are being made by bolts only. This change has been brought about in three years’ time, which is a remarkable achievement.
Today, I feel most satisfied when working on existing bridges that are giving trouble. Diagnosing the problem and finding a cost-effective and practical solution are highly satisfying as I’m able to contribute by saving lots of unnecessary expenditure that would go in modifying a perfectly fine bridge. I have been associated with many field problems in big bridges. One problem was with bending of saddle plate of bearing in the longest span on Indian Railways (154 m), which is in Jammu-Udhampur section in J&K. Another problem that I worked on was regarding less camber in a 125-m span of Ganga Bridge near Patna. Study of these bridges require not just the knowledge of structural engineering, but, also understanding of instrumentation and behaviour of structure in actual practice. The field knowledge is required to be wedded to theoretical knowledge and that is quite difficult to do.
To be able to contribute my bit to the ‘system’, to the country and to the society at large, keeps me motivated when faced with tough situations professionally. Being at RDSO Lucknow, lots of vexed problems that people are not able to solve locally are referred here. These problems provide tough situations as an engineer. However, once the problem is resolved to satisfaction of all, it is a good reward to keep me motivated to take up the challenge whenever such situations come again. At personal level, I turn to philosophy in tough times. No problem looks big enough when we are able to see it in complete perspective. Invariably there is a way out and almost always the situation is not as tough as it could have been.
Steel is excellent in many ways and has few limitations, whilst concrete is also excellent in many ways and has its own few limitations. Since I have more knowledge about steel, I am slightly partial to steel. But as an engineer, I will use steel or concrete as per the benefits of the material to the structure’s need. So, to me, two tools are available: steel bridges and concrete bridges, both of which I will use.
In fact, I have been working to popularize composite (steel-concrete girders) on Indian Railways. There are people who are partisan towards steel and won’t accept the obvious advantage of concrete about no-maintenance requirements, especially in arid areas. Then there are others, partial towards concrete, who cite higher initial costs of steel structures, but, won’t look at life-cycle costing or the advantages of factory production of steel. I have studied both materials, and while working with old bridges (a bridge built as far back as in 1854 was under my charge and working satisfactorily), I have developed great respect for steel. But the kind of work done with concrete structures in metros indicates the strength of concrete as a material, if the field quality issues are addressed.
There are many situations where I won’t consider anything but steel, and others where there will be nothing but concrete. There are only a few areas where I have a dilemma, and then maybe my little partiality will kick in. For engineers who need to take a decision, I would say that we should keep an eye open for developments in both the fields, and be familiar with both the materials so that we can harness the strengths of both the materials.
Use of high strength Friction Grip Bolts is one development, while use of higher strength steel is another development. Earlier, all drawings were with E250 steel, whereas now, E350 drawings are being developed and used widely. We are using new techniques like Fusion Metal Arc Welding, Phased Array Ultrasonic Testing for testing of welds. This way the techniques and technologies are undergoing slow and steady change. For proper corrosion protection, use of paints with life of more than 15 years are under trial, and results in the form of shiny non-corroding structures will be visible in coming years.
Aesthetics is a subject not given due importance in Indian Railways. Architects are almost never deployed on its projects, which results in not-so-superior aesthetics in structures built on Indian Railways. This will change as soon as the projects regarding station development take-off where architects will be involved. The shiny malls, great airport structures etc. all have shown the potential of steel in public spaces in India.
The public perception is formed about the organization as a whole by looking at the kind of structures and their maintenance. The customer orientation is growing on Indian Railways and this situation will surely improve hereon. Adoption of really beautiful steel Bow String Arch road over bridges is a positive step in this direction on Indian Railways. In coming days, these Bow String Arch girders will become ubiquitous on the system and, I am sure, these will help improve the image of railways in this field.