How they did the Taos bridge scenes inTerminator:salvation

Explosions on a bridge
Another of T4's major action sequences involves a large-scale battle
that includes several forceful explosions on a bridge high over a river
gorge. But Snow said that since it was obvious that the filmmakers
couldn't conduct the explosions on the actual bridge--the fantastic Rio Grande Gorge Bridge
near Taos, N.M.--it was necessary to film the sequence in three
different places and then blend the footage together using visual
effects and CG.
The sequence was shot on the bridge, on a nearby roadway and on
a set on a field in Albuquerque, N.M., where they could actually blow
up a truck.

Creating
this action sequence required shooting at three different locations in
order to make a truck explode on the bridge, something that the
filmmakers could not do in real life. Then, it was up to the visual
effects team at ILM to stitch it all together using newly-developed CG
techniques.(Credit: Image copyright 2009 Warner Bros. Courtesy of Industrial Light & Magic)

The sequence, then, involves combining footage from the three different
locations, going back and forth between them depending on the severity
of destruction in each frame, and using CG to patch them together
seamlessly. Snow explained that putting the sequence together meant marrying
footage from all three locations, adding digital backgrounds when
needed, adding railings to the CG bridge, and adding the CG truck to
the bridge.
"We re-projected this onto the (CG bridge) so I could have the
truck fall over the edge, because in the original, it didn't fall over
the edge," Snow said. And "those sort of techniques are just some of
the things that we've been perfecting over the years: re-projection,
the ability to say, 'Well, we can go and do this, shoot at three
different locations, and we don't always have to use blue screen.'
...We can make it so you don't know which bit of the bridge is CG."
And, importantly, it means that for the filmmakers, there's no
worrying about whether they can fulfill the all-important script
element of blowing up a truck on a bridge.

Wow! That's great! Thanks for posting it Banjo.

Verra interesting...

Loved it!