Bridges

The Klondike Highway (Rt 98) in Alaska near the border with Canada is possibly the last place you would expect to see a cantilever spar cable-stayed bridge, but there it was. Cantilever spar cable-stayed bridges are different from suspension bridges such as the Brooklyn Bridge and Golden Gate where the bridge roadway is suspended on vertical secondary cables hung from primary cables looped over towers and anchored into each bank of the river. In a cantilever spar cable-stayed bridge the support cables are attached to the tower or pole in a fan or harp design, thus depending more on the strength of the tower or pole to support the roadway. The tower or pole need not be vertical. A another example of a cantilever spar cable-stayed bridge if the Samuel Beckett Bridge over River Liffey in Dublin, Ireland. The Klondike Highway parallels the White Pass and Yukon Railroad which follows the path would-be gold miners took into the Yukon during the Klondike Gold Rush of the late 1890s. The photo taken from that train as it climbed toward the Yukon show the Sawtooth Mountains in the distance,. Two others photos show different views of an abandoned railroad trestle bridge on that rail line. These are all different from the iron truss bridges commonly build in the US for rail and highway passage over creeks and rivers during the 19th and early 20th century. The last truss bridge example (the green one behind my wife's family) is of a long-standing iron bridge on US 19 in Mercer, PA over the Neshannock Creek after which a nearby restaurant is named - the Iron Bridge Restaurant. The bridge was replaced by a modern and safer structure in 2015. Fortunately, the restaurant continues, serving great food.

6/1018: Added at the end are examples of the truss and cantilever spar cable bridge types from Boston that cross the Charles River a few hundred yards apart - the older Charlestown Bridge and the newer Bunker Hill Bridge.