Do the preparation task first. Then read the text and do the exercises.
Some of the biggest and most expensive transportation projects in the world have involved building bridges. Bridges are crucial links that carry cars, trucks and trains across bodies of water, mountain gorges or other roads. As a result, they are one of the most important aspects of civil engineering and are subject to intense scrutiny, especially when they collapse.
Bridge collapses can be tragic events, leading to loss of life and serious property damage. That's why bridge engineers, designers and builders must always take their jobs very seriously. The best way for them to prevent these accidents is to understand why bridges collapse in the first place. Understanding bridge collapses can lead to major changes in the design, construction and safety of future building projects. The following are main reasons why bridges fall.
Historically, more bridges were made of wood and were much more susceptible to fire. This was particularly true of old-fashioned train bridges, where the spark created by the steel wheels and steel tracks could sometimes cause a bridge to catch fire and burn to the ground.
A large number of bridge accidents occur during the construction of the bridge itself. These accidents are often due to an error made by the engineers, such as a miscalculation. The bridge collapses under its own weight, and this can be deadly for the workers on it at the time.
Earthquakes damage all structures, including bridges. Luckily, this kind of collapse is relatively infrequent, especially with modern bridges. Engineers have learned to design bridges in earthquake zones on areas that are much more resistant to movement.
Some bridge collapses are mysteries, and engineers only realise why after they conduct a complete investigation. In some cases, this could happen because inferior-quality material was used in the construction, or because of a defect in a key piece of the bridge. In other cases, the bridge was designed only to support a certain amount of weight and no more.
Boat or train crash
Both of these kinds of accidents are extremely rare, but boats and trains can cause a bridge to collapse for different reasons. With trains, it's the velocity of the impact that can bring a bridge down. With boats, it's the very large mass they have that can bring about the collapse, even if they are moving very slowly when it occurs.
The best way to avoid bridge failures is to plan for them. Modern technologies that can detect structural weakness, safer working environments and better designs can all help to reduce these terrible accidents.
Hello Finn Pete,
I don't see any question of pre-/postposition in your example. It appears you are asking only about which preposition is appropriate here and I would say that the collocating preposition is 'to': be subject to...
You can talk about something being 'a subject for an investigation', but that has a different meaning: subject to investigation means dependent or conditional on an investigation, while a subject for an investigation means it is a topic for an investigation.
The LearnEnglish Team