Harvard Bridge facts for kids
Quick facts for kids Harvard Bridge |
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Seen from Cambridge (2017)
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| Coordinates | 42°21′16″N 71°05′29″W / 42.35457°N 71.09132°W |
| Carries |  Route 2A |
| Crosses | Charles River |
| Locale | Boston–Cambridge, Massachusetts, United States |
| Maintained by | MassDOT |
| ID number | B160124EYDOTNBI |
| Characteristics | |
| Design | Haunched girder bridge |
| Material | Steel |
| Total length | 2,164.8 ft (387.72 sm; 659.82 m) (roadway) 364.4 smoots ± one ear (620 m) (sidewalk from Storrow Drive to Cambridge only) |
| Width | 69.3 ft (12.42 sm; 21.13 m) (total width) 52 ft (9.3 sm; 15.8 m) (roadway) |
| Number of spans | 25 |
| Piers in water | 24 |
| Load limit | 86.4 short tons (78.4 t) |
| Clearance below | 12 ft (2.2 sm; 3.7 m) |
| History | |
| Construction begin | 1887 |
| Construction end | 1891 |
| Opened | September 1, 1891, 1990 |
| Closed | 1983 (temporary closure for repairs) |
| Statistics | |
| Daily traffic | 49,000 as of 2005 |
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The Harvard Bridge (also known as the MIT Bridge or Mass. Ave. Bridge) is a steel bridge that carries Massachusetts Avenue (Route 2A) over the Charles River. It connects the Back Bay area of Boston with Cambridge, Massachusetts. It is the longest bridge over the Charles River, measuring about 660 meters (2,165 feet) long.
The bridge was built between 1887 and 1891. It was named after Harvard University founder John Harvard. The bridge has been changed and repaired many times over the years. Its main structure was completely replaced in the late 1980s. This happened because of strong vibrations and after a similar bridge collapsed.
The Harvard Bridge is famous for being measured in a funny unit called the smoot.
Contents
Building the Harvard Bridge
People wanted a bridge between Boston and Cambridge for a long time. In 1874, the Massachusetts government allowed a bridge to be built. More laws in 1882 decided where it would be.
Boston and Cambridge had some disagreements about the bridge. Boston didn't like the first plans. In 1887, Cambridge asked the government to make Boston build the bridge. A new law said each city had to pay half the cost. The bridge was estimated to cost about $500,000 at that time.
A special group was formed to oversee the bridge's construction. This group included the mayors of Boston and Cambridge, plus a third person they chose.
Why the Name "Harvard Bridge"?
The bridge is named after Reverend John Harvard. He is the person for whom Harvard University is also named. It is not named directly after the university itself. Other names were suggested, but "Harvard" was chosen.
How the Bridge Was Built
The Harvard Bridge was first planned to be made of wood. But the design was changed to use iron spans on stone supports. The final plans were approved in July 1887. Engineers from Boston helped design the bridge.
The ground under the bridge was very tricky to build on. There is a lot of clay deep underground. The bridge's supports, called piers, had to be built carefully to handle these conditions.
The original bridge had two stone ends (abutments) and 23 stone piers. It also had a special section that could swing open for boats to pass. The main parts of the bridge were made of steel plates.
The bridge connected what is now Massachusetts Avenue on both sides of the river. When it was first built, it was about 660 meters (2,165 feet) long. It was about 21 meters (69 feet) wide.
The roadway had two lanes for horse-drawn vehicles and two tracks for streetcars. There were also two sidewalks for people to walk on. The bridge officially opened on September 1, 1891. The original cost was about $511,000.
Bridge History and Changes
Over the years, the Harvard Bridge has seen many changes and events.
In 1898, special lanes for bicycles were added. These were about 1 meter (3 feet) wide. It took many years for these lanes to connect to Boston's bike paths.
A famous magician, Harry Houdini, jumped from the bridge on May 1, 1908. This was part of one of his well-known escape acts. A marker near the bridge remembers this event.
In 1909, the bridge was found to be unsafe. All of its iron and steel parts had to be replaced. The swing section was also raised a bit.
When the Metropolitan District Commission (MDC) took over the bridge in 1924, they rebuilt much of its upper structure. They replaced wooden parts with steel beams. The swing section was changed into two fixed sections. This made the bridge the same width all the way across.
The bridge was once called the "Xylophone Bridge." This was because of the sound its wooden deck made when cars drove over it. This wooden deck was replaced in 1949 with concrete and a new surface. At this time, the streetcar tracks were removed. Ramps were also added to connect the bridge to Storrow Drive.
Why the Bridge Was Replaced
In the 1970s, people complained that the bridge vibrated too much. A study in 1971-1972 found that the bridge was not strong enough for the heavy traffic it carried. Engineers suggested replacing the main structure of the bridge. This would make it safer and stronger.
In 1983, another bridge, the Mianus River Bridge, collapsed. The Harvard Bridge had similar parts, so it was quickly shut down for inspection. Traffic was limited, and soon all trucks and buses were banned from the bridge.
A plan was made in 1986 to replace the entire upper structure of the bridge. The goal was to make the new bridge look similar to the old one. This was because the bridge was considered historically important. The work was done in two phases and finished in 1990. The cost was estimated to be around $20 million.
Recent Updates
In 2014, new street lights were planned for the bridge. An anonymous donor paid for this upgrade. The new lights were installed in 2015. They help make the bridge safer for people walking and driving. They also highlight the famous smoot marks on the sidewalk.
The Smoot Measurement
The Harvard Bridge is known for being measured in a very unusual unit: the smoot.
In 1958, students from the Lambda Chi Alpha fraternity at MIT decided to measure the bridge's eastern sidewalk. They used one of their shortest new members, Oliver Smoot, as their measuring stick. Oliver Smoot was about 1.7 meters (5 feet 7 inches) tall.
The students painted marks every 10 smoots along the bridge. These marks show that the bridge is 364.4 smoots long, "plus one ear." This "plus one ear" part was originally "plus or minus one ear," meaning there was a small amount of uncertainty in the measurement. But over time, the "or minus" part disappeared.
The fraternity members repaint these marks twice a year. They used to do it secretly, but now it's done openly. When the bridge was rebuilt in the 1980s, the new sidewalks were even made with slabs that were the length of a smoot. Police officers even use the smoot marks to help describe where accidents happen on the bridge.
The length of 364.4 smoots is about 620 meters (2,030 feet). This is a bit less than the bridge's official length of 660 meters (2,165 feet). This difference might be because of how the sidewalks were laid out in 1958.
Images for kids
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Postcard showing Harvard Bridge looking toward Boston in 1910.
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Postcard showing Harvard Bridge, looking toward Cambridge and MIT sometime between 1916 and 1924.
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The Harvard Bridge is decorated with both serious and whimsical works of art.
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Bridge viewed from the upstream Cambridge side in 1985. Construction barrels restricting traffic from the outside lanes, and general wear and tear are visible.
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Roughly the same view, in 2009. Superstructure is in much better shape only 20 years after completion, than the 1985 superstructure was roughly 40 years after its most recent major work.
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Underside of the bridge in 1985. Image shows how the bridge was originally built, and later modified, but before the superstructure was replaced.
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Underside of the bridge in 2009. Image shows how the replacement superstructure was built, with six longitudinal girders, different bracing, etc.
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See also
In Spanish: Puente de Harvard para niños
