Nostalgia & History > How does this work?

Does the outer portion slide to the left? If so what powers it?

https://historicpittsburgh.org/islandora/object/pitt%3A201203.1915.A/from_search/-298

Construction of Ohio Connecting Railway Bridge.

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It looks to me like they are replacing an older bridge with a new, larger, structure being built around the ourside of the older one.

crackerjackhoghead Wrote:
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> It looks to me like they are replacing an older
> bridge with a new, larger, structure being built
> around the ourside of the older one.

Hoghead is correct.  This bridge was so busy they left the old bridge in place while they built the new one around it.  Being a cantilever, both sides were being kept even (balanced) as work progressed.  When the new bridge was complete, they dismantled the old bridge.

This story is told in one of the 'Triumph' books by Charles Roberts.