There are large blind areas and blind spots around tractor trailers which truck drivers cannot see from the driver’s seat or by using their mirrors.
Most car drivers, even experienced car drivers, are not aware of how large these blind areas and blind spots can be.
Here are some selected YouTube videos:
This is a short video from May Trucking Company. based in Oregon.
This one is from the British Safety Council and shows how a truck driver cannot see cyclists when turning to the blind side. Note that this video shows the blind spot to the left of the truck. Remember that British vehicles are right hand drive so this blind area is on the left with British trucks. With left hand drive trucks like those in North America this blind spot is on the right side of the truck. But the same idea is applicable in both cases and applies to any vehicle in this area around a truck, not just to cyclists.
This is a 1991 video by the American Trucking Association. It is a bit dated but it illustrates the basic idea of bliand areas around tractor trailers.
The collision between a Porsche and a tractor trailer happened on a British motorway, the M621, near Leeds, on 6 May 2010. The collision happens a 1:08 of the video:
This is a political video by IconicNY protesting a proposed garbage dump in a New York City residential district but it illustrates some of the blind areas around a typical garbage truck. These areas are bigger around tractor trailers.