Flyovers: City planners plump for new technology

By Govind D.Belgaumkar

BANGALORE, OCT. 13. The City planners are increasingly preferring the pre-cast segmental construction to the conventional construction on the site for flyovers.

The type to construction one witnessed at the Richmond Circle, wherein the traditional method, i.e., constructing the long decks of the flyovers at the site, was adopted is now passe.

Though the conventional method is cheap, the City planners are favouring the modern method wherein the parts of deck slabs of the flyover are made in a separate location and mounted on the pillars at the site. An example of this is the recent tenders called by the Bangalore Mahanagara Palike (BMP), which has specified that the firms bidding for them should have constructed at least one flyover or underpass using the pre-cast segmental construction.

Another example is the Hebbal flyover, which has been assigned to Gammon India by the Bangalore Development Authority (BDA). The BDA is the first agency to invite tenders opting for the new technology.

However, the BMP was the first to own a pre-cast segmental construction flyover though by default if not by design. The L&T, used the new technology for the Rs. 94-crore Sirsi Circle flyover, though the BMP itself had not asked for this technology. It was a turnkey project, wherein the firm evolved its own design and constructed the flyover using the technology.

The BMP has come in for criticism for opting the costlier method of construction. Critics point out that whereas the Sirsi Circle cost Rs. 33,000 per sq. metre, the conventional flyovers coming up at Whitefield and Benniganahalli cost only Rs. 10,000 to Rs. 12,000. The Richmond Circle has cost the BMP between 12,000 and Rs. 15,000 per sq. metre. The BDA says the cost of the flyover coming up at the Hebbal Circle will not exceed Rs. 16,000 per square metre though it is adopting the latest technology.

To this, the sources in the BMP and the BDA point out that the pre-cast bridges are constructed within a short period of 12 to 18 months while the conventional bridges take double the time. Since the segments of the deck are built in a separate site, the quality can be controlled. More importantly, they point out, these bridges cause less disturbance to the traffic, a key concern of any City planner.

The sources say that construction of conventional cheaper bridges can still be considered where one has adequate space with less or no traffic flow as was the case with the Benniganalli flyover, coming up near K.R.Puram.

On the other hand, those arguing against the pre-fabricated bridges argue that there are only two firms -- L&T and Simplex -- which have constructed such flyovers. However, sources in the BDA point out that there are at least three more firms -- UP State Bridges Corporation, Bhageeratha, and AFCONS -- which have constructed pre-fabricated flyovers. This is clear from the biddings made for the Hebbal flyover, they say.

Sources say that pre-fabricated bridges are better in quality and maintenance-free. Thus, they say that the ``pre-fab'' bridges will turn out to be cheaper in the long run. Besides, in an era where time is money, construction of flyovers in time and in a short period, is always preferable.

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