‘Good owner-designer tie is key to good design’
Last month, Mumbai lost urban planner Shirish B Patel, who designed India's first flyover. HT pulled out an essay of his on the creation of the SoBo overpass
MUMBAI: In May 2015 it was 50 years since the opening of the Kemp’s Corner Flyover. As its principal designer, I suffered some forced jubilation in 1965 over its being the first flyover in India. Had I known then of the succession of flyovers that would follow, some spectacular, some disastrous, and what they would do to the fabric of our cities, I might have been even more reluctant in my enthusiasm.
It took seven months to build. Design-cum-build tenders were invited by the Bombay Municipal Corporation in the middle of 1964. The Executive Engineer in charge was MS Nerurkar, a fine, experienced officer who had happy memories of working for my father many years earlier. We quickly became good friends, with high regard for each other. It was the first of many experiences where I found that to produce a good design what you need above all is a good owner-designer relationship, and (with the same designer) the better that relationship the better the design.
Mine was a fledgling design office at that time, perhaps half a dozen of us altogether, all engineers and one clerical person, no draftsmen. We believed in engineers making their own ink drawings. We teamed up with a contractor, BG Akerkar, whose bid was the lowest, at about ₹17.5 lakhs. I had to satisfy Mr KK Nambiar, the senior design review person, that what we were suggesting would work. Nerurkar was particularly pleased, he told me later, that I had a convincing answer to each of the questions put to me. So we got the job. This was mid-1964.
At the time of bidding we asked for trial bore details to establish the strata below. Nerurkar said there was solid rock at both ends of the required central span of 100 feet. On what evidence? Well, India House on the north-west corner had been recently built on rock just a few feet below the surface. And at the southern end BMC had recently installed a statue of a Parsi gentleman and found rock very close to the surface. Therefore, we were told, there was solid rock at both ends of the main span, just below ground level.
So we designed the flyover as an arch bridge, founded on solid rock at both ends, with the deck riding over the top. We decided to make it a tapered arch, narrow at the base, widening at the crown to the full width of the carriageway, and narrowing again at the other end. The reason was that even after providing for a central clear span of 100 feet required by BMC (high enough to clear double-decker buses below), we would have ample space at either end with reducing height in which a car might comfortably make a U-turn. The narrowing of the arch towards its base, albeit unusual, made perfect sense because it would give more space for these U-turns below.
July and August of 1964 were spent furiously producing drawings for the bridge to be able to start construction post-monsoon. The deadline for completion was March 1965. We were all set and ready to go when post-rains we could begin trial pits to check the rock levels at either end. At the northern end, opposite India House, sure enough we found rock a few feet below, as expected. But at the southern end, about 30 or 40 feet beyond where the Parsi statue had stood, the trial pit got deeper and deeper with no sign of rock. Finally, when we were about 20 feet down, a police inspector pulled our people out and stopped our work saying it was too dangerous to go further. So finally we got the BMC to do what it should have done in the first place, that is, make a trial boring. It revealed rock at a depth so far below that it could no longer provide the foundation that an arch would need.
We tried hard to find a way to save the arch. One way would work, but in future you would never be able to cut through it to lay a sewer or water supply line should you ever need to. So: workable, but unwise. Had we known about these foundation conditions earlier, would we ever have thought of an arch? The answer was absolutely never. It took a few days of agonising to accept this. Giving up a design you have lived with day and night for several weeks is like throwing away a baby you have nurtured until then, and starting over. We had no choice, and we were under pressure to still deliver the project on time.
So we decided on a central span, resting on columns 100 feet apart, but with overhangs to give the U-turn space we had earlier visualised with the arch. In the Kemp’s Corner project one improvement was this U-turn space at either end; another was the zigzag retaining wall at the southern end, under the ramp, which is not only structurally efficient but also provides car parking space and room for a toilet or other public facility below. Neither of these was a requirement of the BMC. We could have had solid ramps on either side of the 100 ft. gap as far as they were concerned. But with any client it is important to look beyond the brief, which is a kind of minimum compliance requirement, at what else might be possible and in the best interests of the client. We were on a fixed-price contract, and it is to my contractor friend Akerkar’s credit that he gave us a free hand with the design, not insisting on the cheapest solution and accepting the more meritorious one.
We were now into October 1964. Foundation drawings were urgently needed to start construction. We had no time to prepare any drawings of the finished bridge, not even a general layout. Tofique Fatehi (later an associate in our office) and I carried the design around in our own heads while churning out drawings for the work to proceed. Both of us must have worked 16-hour days for the next two months, until finally drawings were sufficiently ahead of construction that we could ease off and revert to a normal working day.
As an engineering design office we decided early on that we would always involve a Consulting Architect in each of our projects—required to produce no sketches or drawings but only to advise on aesthetic aspects and the preferred option among alternatives. In this case we worked with Charles Correa. He particularly wanted the bottom of the flyover to be “boat shaped”.
After the flyover was ready, it was carefully and thoroughly load tested. Heavily loaded trailers were placed at different locations on the bridge, and deflections measured using instruments and staff kindly provided by IIT Bombay. The trailers were also left in position overnight, and deflections measured again. All readings confirmed that the bridge was stronger than the specifications demanded. It was only after these tests were complete that the bridge was opened to traffic.
Flyovers have since proliferated all over the country. Are they a good or a bad thing? Any particular one could be either. Which it is, good or bad for the city, depends on its particular context and depends also on its precise detailing. And one factor too easily forgotten is that an alternative to a flyover is an underpass, which is often less messy and certainly less of a blight on the cityscape above.
Flyovers can improve the throughput of an intersection, particularly a complex intersection where several roads meet (Kemp’s Corner was a junction of six roads), and traffic from each direction has the option of going into any of the other directions.
But flyovers (or underpasses) are no panacea. They can do very little to improve overall roadway capacity, beyond clearing the bottleneck that a particular intersection might represent. So they need to be put in judiciously, only where it is clear that improving a particular intersection’s capacity will really help traffic flow, as for instance at an intersection on an arterial road. And there too careful thought needs to be given to whether they should be in the arterial or in the transverse direction.
Finally, although the idea of a particular project may come from anywhere (in this particular case the flyover was a suggestion of Wilbur Smith and Associates, Transportation Consultants) we must not forget that flyovers and similar infrastructure interventions are usually driven by public servants who take upon themselves the sense of ownership of the project. It is the quality of these public servants that ultimately determines the quality of the results. The Kemp’s Corner Flyover was driven by M S Nerurkar. It was he who pushed for it, and discussed and approved each suggestion for change in design or construction method. It is his insight and imagination that have brought benefit to traffic at that location ever since.
(This is an abridged version of an article titled, ‘Kemp’s Corner Flyover at 50’ penned by Shirish B Patel for the Urban Design Institute’s annual journal, ‘The Mumbai Reader’, in 2017, on the making of the flyover.)
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