2.3.1  How do I get across the broken bridge?

            The real problem: "I try to take a running jump across the
            broken section of the bridge but I aways fall down."

            You have to perform a running jump and grab to cross the
            broken bridge.  Most people haven't really learned their
            running jumps by this point, but it's important to WALK to
            the very end of the bridge, take a hop back which will
            give Lara the exact run-up she needs, and the performing a
            running jump.  In midair, press the action key and Lara
            will grab onto the opposite side.