Pyrmont Bridge bustles with pedestrians and cyclists, connecting the city with the peninsula. One hundred years ago it was just as important a transport connector, but it was jam-packed with horses and carts alongside pedestrians. This morning on 2SER breakfast with Tim Higgins we chatted about Pyrmont Bridge's history. I kept banging on about how unique the Pyrmont Bridge is. So why is it special? Well, at the time of construction (1899-1902) the swing span of Pyrmont Bridge was one of the largest in the world. It was also one of the first swing bridges in the world to be powered by electricity. It could be opened or closed in just 45 seconds. It was powered by electricity generated from the nearby Ultimo Powerhouse (now the Powerhouse Museum). But world-firsts aside, it also has a special technical design that was developed right here in Sydney. Percy Allan was the Chief Engineer for bridges at Public Works and he developed a new design for timber truss bridges, using Australian ironbark timber for its strength. The design type became known as the Allan truss bridge. Allan's innovations simplified the design, increased load bearing capability, reduced construction costs, and made the construction and maintenance of timber truss bridges much easier. Pyrmont Bridge is a unique type of Allan timber truss bridge, comprising 12 timber truss deck spans. 105 timber truss bridges were built in NSW between 1894 and 1929, and this is the only one of this particular design. So you won't be surprised to learn that the Pyrmont Bridge is listed on the State Heritage Register. You can read all about the Pyrmont Bridge, and its neighbouring swing bridge the Glebe Island Bridge, in the Dictionary. For those you keen to get into the techncial details of timber truss bridges, take a look at this survey of timber truss bridges that the RTA undertook. 2SER podcast the Dictionary's chats with Tim Higgins or tune in next Wednesday on 107.3 at 8.20am for another Sydney history highlight.