In Boston, behind the Spaulding Rehabilitation Center, is a viewing area that includes a sign that has a description for two bridges: the Leonard P. Zakim Bunker Hill Bridge and the Boston and Maine Railroad Bascule Bridges.
The text on the sign is as follows:
"Leonard P. Zakim Bunker Hill Bridge
The Leonard P. Zakim Bunker Hill Bridge, dedicated in 2002, carries Interstate 93 over the Charles River. It replaced the Charlestown High Bridge, completed in 1954. The Zakim Bridge is a cable-stayed harp design, where the cables are attached more or less in parallel. In a fan design, the cables are attached to or pass over the top of the bridge towers. The bridges was named for the nearby Bunker Hill Monument and for the New England director of the Anti-Defamation League, who was widely respected for his efforts in 'bridging communities.'
Unlike many suspension bridges, which are symmetrical in all three dimensions - plan, elevation, and section - the cable-stayed Zakim Bridge is asymmetrical in all three. In plan, an on-ramp from the North End added two lanes cantilevered on the downstream side of the bridge. In elevation, the highway is coming out of a tunnel and rising to meet the ramps on the north side of the river. And in section, since there was a commitment to keep the old bridge open to traffic until the new bridge was completed, the south back span (the section of the bridge between the tower an the end of the cables) is shorter than the north bank span. In describing the bridge, the engineer in charge of its constructionsaid it would have been impossible to design the bridge without supercomputers to do the calculations.
Boston and Maine Railroad Bridges
Two railroad bridges across the Charles connect Boston's North Station to the commuter rail lines nroth and west of the city. The bridges were built in 1931. Each bridge is a single-leave bascule, a counterbalanced structure in which the 629-ton overhead concrete counterweight is lowered to raise the steel truss bridge. The bridges were part of the expansion of the Boston & Maine Railroad, including a new terminal and the Boston Garden. One of the railroad's predecesors, the Boston and Lowell, the first movable railroad bridge in America on this site in 1835.
Pier, Ramp & Dock, Spaulding Rehabilitation Hospital
The hospital created new space along the river for adaptive water sports facilities, including windsurfing, kayaking and canoeing. Designed by the Boston landscape architects Reed Hilderbrand, the pier also provides access to the rich plantings and broad vistas in Nashua Street Park."
The Zakim Bunker Hill Bridge is a prominent feature from this view. It has the appearance of a sailboat sail face on. The Charles is not a very large river, but the bridge easily clears it. Before this layout was approved and built, there were several designs, or 'schemes' as they were termed, including the 'Z' scheme, which included the most ramps leading to the bridge. At the time it was built, it was the widest cable-stayed bridge in the the world, and only one of a few asymmetrical ones. There are 10 lanes on the bridge. The total length of the bridge is 1432 ft (436 m), the span is 745 ft (227 m), the width is 183 ft (56 m), and it clears the river by 40 ft (12 m).
The Boston and Lowell Railroad was one of the three original railroads that linked Boston with other cities. The Boston and Lowell, as the name indicates, went between Lowell, a new textile mill city, and Boston, the financial center of New England.
There is a trail along the Charles River that leads to the observing area. The trail ends there. To continue down the river, you must walk out to North Station/Boston Garden, walk around it, then walk down the next road to the Charles River new dam and locks.
Sources:
Leonardpzakimbunkerhillbridge.org:
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visit link)
Wikipedia (Leonard P. Zakim Bunker Hill Bridge):
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visit link)