online engineering degree/engineering degree online/online engineering courses/engineering technology online/engineering courses online/engineering technician degree online/online engineering technology/electronic engineering online
Last Thursday, a "duck tour" amphibious vehicle used to show tourists the city of Seattle from both land and water was involved in a crash with a charter bus on the city's Aurora Bridge. Four international students on the bus died and several others were injured. This accident has raised concerns that the vehicles used for amphibious tours are inherently unsafe.
An eyewitness said that the amphibious vehicle, which appears to be a World-War-II-vintage "DUKW" type, was traveling on the bridge when its left front wheel locked up, causing it to veer into the path of the bus. The bus was carrying students from North Seattle College, and the four who died were from Austria, China, Indonesia, and Japan. A later report says that investigators have found that the DUKW's left front axle was sheared off in the accident. The investigation may take a year or more to complete.
The usefulness of a craft that can negotiate both land and water is obvious if you are an invading army, and that is why the U. S. military bought thousands of six-wheeled DUKW-type vehicles from General Motors during the Second World War. After that conflict, they went on the surplus market, and in 1946 two enterprising gentlemen named Mel Flath and Bob Unger bought some and started what is now known as Original Wisconsin Ducks on the banks of the Wisconsin River. The unique appeal of seeing a locale both from streets and a river without having to disembark from a land vehicle into a boat made their idea a success. Since then, the concept has spread around the world, and today over 30 cities have some form of amphibious-vehicle tours available.
In the U. S., there are both state and federal regulations governing the operation of such tours, and the vehicle involved in the Seattle accident was reportedly inspected annually by a federal inspector. Despite such measures, you might wonder if 70-year-old boats that weren't designed for ordinary city streets are simply outmoded and need to be retired.
One main concern voiced about the DUKW-type vehicle is visibility. The driver rides high above the street and the view immediately in front of the craft is blocked by the bow. This problem has led to some non-fatal accidents involving low-slung cars being rear-ended by a DUKW. Another concern is that the technology used is simply wearing out, and anything that old needs to be replaced by a more modern design.
As defenders of the DUKW point out, the wearing-out argument is countered by the fact that regular hull inspections and mechanical checkups can catch problems associated with aging vehicles and fix them before they become the cause of a bad accident. In 1999, a DUKW used for tours in Hot Springs, Arkansas sank and 13 people died. And in 2010, a DUKW's engine failed in the Delaware River, and a barge crashed into it and killed two passengers. The Delaware River incident was later attributed mainly to an inattentive tugboat pilot, who was on his cellphone instead of watching where he was going. The available accident record involving DUKWs does not show that any particular age-related defect is causing large numbers of accidents. On the contrary, doing good maintenance on the vehicles seems to keep them going indefinitely.
It would be nice if we had a database of total number of passenger-miles carried by DUKWs and could compare the vehicle's safety record with those of other modes of tourist travel—charter buses, for instance. But no such database apparently exists, and it would be a lot of work to estimate the customer volumes of a number of privately owned tour companies throughout the world.
Part of what is going on here is what I might call the pathos effect. News media tend to report on incidents that have an emotional tug to them. The contrast between the joyful pleasures of a holiday excursion and the tragedy of sudden death by drowning or collision is pathetic, in the technical sense of arousing pity. It's one thing if a commuter is hit by a bus, or a drunk driver runs into a tree and kills himself. It's a higher level of pathos if some international students who are getting their first sights of America suddenly have their lives cut short by a crash with another sightseeing vehicle. So other things being equal, fatal accidents involving duck tours are going to get publicity way out of proportion to the actual body count, to put it somewhat cynically.
Nevertheless, it's a valid question to ask whether these mid-twentieth-century vehicles should be replaced by more modern ones, or whether the existing fleets can be made safer.
Regular inspections with annual certifications are already part of the ongoing effort to keep these types of tours safe, and if some maintenance lapses are discovered in the Seattle accident, increased scrutiny of the integrity of these inspections will be warranted. But until we find out exactly what happened to cause the wreck, such measures are premature.
The visibility problem is relatively easy to solve these days with small video cameras and displays. Not too long ago, I helped a friend of mine install a backup video camera on the bumper of his large pickup so that he can see anything low that he might not want to back into. With this type of installation for a DUKW, there might be some issues involving waterproofing and so on, but these can be dealt with relatively easily, leading to greatly improved visibility in the vehicle's blind spots.
When the investigation of the Seattle duck-tour accident is complete, we'll have a better idea of why it happened and whether negligent maintenance or some other cause was at fault. In the meantime, it's probably safe to say that tourists who want to see London or Malacca or Singapore from an amphibious vehicle are not taking their lives in their hands when they get aboard. But it wouldn't be a bad idea to find out where the life vests are kept.
Arctic sea ice extent and especially concentration are now growing rapidly, as illustrated by the Naval Research Lab animation on the right.
The image on the left shows that on August 25, 2015, sea surface temperatures near Svalbard were recorded as high as 17.3°C (63.1°F), as marked by the green circle, a 12.1°C (21.8°F) anomaly.
