On Tue, 2010-05-25 at 08:33 -0500, Lord-Castillo, Brett wrote: > So, the real argument here is what is a bridge and what is a tunnel? Many > people considered depressed highways to be tunnels rather than the roads over > them to be bridges. I saw USGS topos mentioned earlier. Not all manmade cuts > are reflected in topo lines. Manmade cuts that are structures are not > considered bare earth and are left out. But then you get to the weird idea of > "are the sides of the depressed highway vertical concrete or sloped ground?" > and other such criteria. > --Brett
What I used to distinguish a bridge from a tunnel is to ask, "Is it a span or a pipe?" A "pipe" puts (or leaves) the support structure around the tunnel. A span puts the support structure under the bridge. There will be some places where this becomes ambiguous, but I haven't found any in my area. - Val - _______________________________________________ Talk-us mailing list Talk-us@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk-us
