Construction Trash

When I think of garbage I normally think of items that get thrown out on a daily basis such as food scraps, paper, packaging, etc. More recently I have been wondering about what happens to houses, or buildings, when they are torn down or remodeled. Could have the existing materials been salvaged instead of replaced? I took both of these pictures while in New York City for a class called BIDS: New York and Toronto. The one picture shows an old house that has fallen into a state of disrepair, and was scheduled to be demolished. I wonder if the rubbel ends up in the same land fill as our everyday garbage, or if it can be reused some how. The picture below is of an old elevated railroad track in the Meat Packing district. At one point the track was slated to be demolished, much like the house above. But a few people had the idea to recycle the track and create a park on it. The picture is of the finished park, called the High Line. Seeing that these old tracks were put to another use makes me wonder about all of the garbage that is produced from construction/demolition, and how much of it could have actually been save, or reused like this park.