Sat, Jun 22, 2013 - Page 8 News List

[ LETTER ]

Bridges need expert probe

It is sad to see what actions are being taken to prevent another bridge disaster and obvious that the core issue needs attention in a comprehensive fashion.

Once again politicians are debating broad changes in law, but the important details have not been considered.

In any failure of this sort, the first thing to do is to determine what the source of the failure was. Was it poor construction, poor maintenance, or poor engineering? Without fully discovering why this happened, it is likely that all measures taken will miss the mark.

The facts are quite evident.

One, the bridge failed with only one pedestrian on it. That is extremely abnormal, as the bridge was designed for many more people. It certainly was not overloaded.

Two, it was not undermined. This might be the most common form of failure from natural erosion or collision damage.

Three, the span’s beams did not fail. This might occur from age or collision damage.

It rotated over on its side because of its unusual curved design.

The span’s center of gravity was not stable, so added steel had to be relied on to keep the span stable. Poor maintenance, a slight collision, or an earthquake could all have contributed to sudden and complete failure.

Only the steel that was preventing it from rotating appears to have failed and nothing else. It should have been monitored regularly.

Many engineers might recognize that this was an accident waiting to happen and feel that it never should have been so “artfully” designed.

There was not any real need for the curve and it created an added danger. A straight span would have been much safer and easier to maintain.

Arguing about jurisdiction in this case is absurd. Any bridge over a freeway or a railway should be a national priority, as many more lives are at risk when such a bridge falls onto the roadway below.

Requiring inspections of all pedestrian bridges in the future certainly might be helpful.

However, if you don’t have bridges categorized by their specific design and engineering, points of potential failure may easily be overlooked by the untrained eye. Taiwan has a great number of pedestrian and other bridges of varied design.

Therefore, it is not enough to call for bridge inspection alone. Taiwan needs to have qualified inspectors that know the specific faults of each type of design they are responsible for.

If an old bridge was never designed properly, it should be a candidate for immediate replacement. That appears to be the case with this bridge.

It seems very obvious that this span was not a good idea from the beginning and not subject to the kind of conservative engineering peer review that any pedestrian overpass over a freeway or a railway should be subject to. Due to the potential for it to rotate, it needed special monitoring, not just visual inspection. Of course, as long as Taiwan allows engineers to rent out their licenses to others without accountability for such failures, we are going to see more failures than other countries.

We were extremely fortunate that only one person was injured and so slightly. It could have been a train wreck.

Above all, fancy designs of curves and such should be looked at more closely and more often than others.

The other sections of the Keelung bridge seem conventional and may have many years of stable use ahead.

This story has been viewed 1134 times.
TOP top