Given the expense and careful attention to detail that went into building the Titanic, can you speculate as to why it did not have a double hull?
This is a point of debate. Looking at the long view, even though double hulls did exist at the time there would have been pressures on shipbuilders not to build double-hulled ships simply because they would be more expensive. There would also be a tendency among ship owners, operators and captains to argue that they know how to steer their ships so that they don't puncture a hull, that a double hull is an unnecessary expense. As long as there were no accidents it would be hard to argue against that reasoning. Then when something like the Titanic happens there's a reaction to that failure, thinking that if there was a double hull the ship wouldn't have sunk.
What parallels can you draw between the Titanic and the Costa Concordia, which ran aground in January off the coast of Italy, killing 30 or more people?
There's going to be a lot of pressure to operate cruise ships differently. They're not going to be going close to land as that one did. There are probably also going to be calls for design changes. I understand it took them quite awhile to pump the fuel out of the ship, so making that easier will be an area they'll focus on. The Costa Concordia also listed so badly they couldn't get the lifeboats down on one side. That's something that will be looked at.
The Costa Concordia situation is analogous to the Titanic's sinking. In the case of the Titanic, ships were moving through the North Atlantic at a regular rate at that time, and the fact that they almost never hit icebergs was interpreted as: "We don't have to hit icebergs, we know how to avoid them." This raises the level of confidence almost to overconfidence that nothing's going to happen because nothing has happened, which is not logical, of course.
What should the shipbuilders have learned from the Olympic's accident months before the Titanic struck the iceberg?
This should have been a warning. There's so much written about the Titanic, and it's hard to separate what's fact and what's fiction. My understanding is that the way the Titanic was designed, the emphasis was placed on surviving a head-on collision. The idea of a side grazing was apparently not anticipated, although it's hard for me to imagine why.
How much of a factor do the materials used to build a ship play into the safety and reliability of that ship?
Part of a design is to specify the materials. They were building the Titanic and its sister ship the Olympic at the same time, so they needed a lot of rivets. It turned out those who supplied the rivets were overwhelmed by the shipbuilder's demands. This led White Star to look for a broader range of providers, so the quality control wasn't as good as it would have been if they were dealing with a single supplier. Some of the rivets in the ship were steel, like the hull plates were, but some of the rivets were made of iron, and not the best iron. There were rivets that were put into the ship that were not sound. Getting the right materials continues to be an issue for large building projects even today.
How do engineers take into account poor judgment or misuse when designing something as massive and complex as an ocean liner?
It depends on whether you look at the ship as a structure made of steel and rivets and so forth or if you look at the ship as part of a larger system that transports people overseas over long distances through waters where there are icebergs. Not only does a structure need to be robust, it also needs to be robust under operational conditions where people make mistakes and things go wrong. The systems approach was very important to understanding what happened to the Titanic.
For a more recent example, look at the space shuttle program. Before the Challenger accident, there were 24 successful space shuttle flights, although quite a few of them actually had leaks in the O-ring, which turned out to be the weak link in the design and fatal for the Challenger. But it was rationalized away in the sense that, true there were leaks, but the shuttle missions were completed anyway. The system—which includes both the equipment and the people in charge of operating that equipment—tolerated those risks, and for awhile we were able to bring the astronauts home safely. Because no one can foresee all of the conditions that a design will be subjected to, managers, whether it's a ship's captain or NASA engineer, need to know and respect the limitations of their equipment.