Many Bridges Are Structurally Defective

As an essential and integral part of our country’s transportation system, highways and road networks cover nearly 90 per cent. Bridges that connect these gargantuan networks of highways ensure businesses move their goods seamlessly throughout the country. To keep the operation of this labyrinth transportation artery smooth and intact, the health of this system needs to be regularly assessed. In other words, bridge inspection and maintenance must be periodically conducted. Bridge inspection and maintenance activities ensure that our bridges can remain safe to operate for all users. Yet, with years’ of neglect and no repairs, compounded by wanton use of substandard materials and design flaws, many bridges in Nepal are on life support right now. Ever spiraling shady construction practice and persistent poor supervision during construction is taking a toll on the gut of the bridges; consequently in the near future, many of them are certain to be doomed. 

Legislation 

Bridge inspection, unbeknownst to many until 1967, the Silver Bridge collapse in the US prompted the Congress to pass legislation to ensure the safety of bridges and the travelling public. The National Bridge Inspection Standards (NBIS) is the result of this legislation. The NBIS mandates inspection of all publicly owned bridges greater than 20 feet in length. In most cases, routine inspections of bridges are required at least every two years after the completion of bridge construction and open to the public. Routine inspections comprise of superstructure, substructure and foundation inspection. Another important safety aspect of the NBIS is load rating. A load rating is the determination of safe load carrying capacity of each bridge.  Sad to say but true, bridge inspection and load rating of bridges are still miles away from the radar of our concerned authorities.  

In our country, millions of us cross over bridges every day without giving them much thought unless we hit a pothole notwithstanding the problematic infrastructure black hole goes much deeper than on the surface. It goes to spalling concrete, corroded steel –- the smoking guns — and so forth. The foundation of many bridges has undergone significant scour and are on the verge of caving in. The fact is that nearly thousands of bridges, in perspective, three out of four bridges are in dilapidated condition, structurally deficient, only waiting for catastrophe to occur. These bridges are in such a “poor condition” that they must be either replaced or repaired in a very dramatic way. They must be fixed today. 

Take an example of the antiquated bridge, the Narayani River Bridge, built about forty years ago. The Karnali River Bridge is not any better than the Narayani River Bridge. No technical personnel have visited to evaluate the health of these bridges ever since they were opened to the traffic decades ago. All these bridges are just waiting for tragedies to occur and havoc to erupt.   In recent days, about 200 to 250 bridges are built annually by the Department of Roads alone and of a similar range by the provincial and local governments. Major bridges like the Karnali Bridge, etc. are built with the financial and technical assistance of donor countries. The tradition here is that once it is built, it is left — uncared for or untended forever. All bridges that were constructed five or six decades ago have already passed the expiration date. 

Usually, the life of constructed bridges here deems to be 30 to 40 years old.  Thus, all these bridges are aging, in the state of decay, and call for a severe need of updating. Many bridges have inadequate vertical or horizontal clearances or inadequate approach roadway geometry. These bridges do not serve current traffic demand or meet current standards — forget about the future traffic demand despite that being the design norm. Worse yet, many of these bridges act as bottlenecks, increasing congestion and crash vulnerability due to inadequate widths, lanes, or shoulders, substandard vertical clearance, or insufficient lanes for traffic demand. 

Poor drainage system

The poor drainage system has further exacerbated the problem especially in the rainy season. In brief, the quality of our infrastructure is pathetic. Who is actually responsible for the upkeep of these bridges? All look to be shying away from the responsibility on the pretext of inadequate budget. Accidents have been a daily occurrence on these bridges, and misery is mounting on citizens one after the other. For public safety and to curb future losses, experts have called for preventive measures of these bridges at the earliest. New technologies, materials, evaluation techniques, and construction methods have advanced in recent years to take these measures. With new innovation and evaluation methods, engineers can now identify problems earlier, increase the lifespan of our bridges, stretch limited resources, and prioritise public safety. Sooner than later, the government must take responsibility. 

A popular saying goes “prevention is better than cure”. A concerted effort must be made from all tiers of the government to reduce the number of structurally deficient bridges across the nation. Although structurally deficient bridges are not inherently unsafe in itself, they call for a substantial investment in the form of replacement or significant rehabilitation, and they pose a substantial risk of current and future public casualties. Thus, without further ado, the nation must have a systematic programme for bridge preservation whereby existing deterioration is prioritised, and maintenance and upgrades are placed in action. Otherwise, only counting days to succumb to the impending peril as near as tomorrow. 

(The author holds a PhD from Tokyo University and a postdoc from the University of Illinois at Urbana-Champaign, USA.)