Harvard Bridge

In 1874, the Massachusetts Legislature authorized construction of a bridge between Boston and Cambridge, and in 1882 follow-up legislation set out its location. The bridge was to have a draw with an opening of at least . Boston interests opposed the bridge, mainly because it did not provide for an overhead crossing of the Grand Junction Branch of the Boston and Albany Railroad. Further legislation in 1885 changed the draw to a clear opening of at least and no more, until the other bridges below the proposed location were required to have a larger opening. There was still no substantive progress until 1887, when Cambridge petitioned the Legislature to compel Boston to proceed; the resulting act required each city pay half the cost, and allowed Boston to raise up to $250,000 (US$ with inflation) for this purpose, in excess of its debt limit. This implied an estimated cost of US$500,000 (US$ with inflation) for the bridge. The Legislature provided for a bridge commission, to consist of the mayors of Boston and Cambridge plus a third commissioner to be appointed by the mayors. The mayors of Boston and Cambridge, Hugh O'Brien and William E. Russell, appointed Leander Greeley of Cambridge as the third commissioner, though this appointment changed over time. The commission's 1892 report claimed: Name The bridge is named in honor of John Harvard, whose philanthropic gift was used to establish Harvard University. Other names suggested included Blaxton, Chester, Shawmut, and Longfellow. ==Engineering==

in 1910, from the roof of the Riverbank Court Hotel, which is now Maseeh Hall, a dormitory at the Massachusetts Institute of Technology and MIT Originally projected as a wooden pile structure with stone pavement for the first (because the Charles River Embankment extension was expected to take that space) the design was changed to be entirely iron spans on stone piers. The general plans were approved on July 14, 1887. The engineers were William Jackson (Boston City Engineer), John E. Cheney (assistant Boston City Engineer), Samuel E. Tinkham (assistant engineer), and Nathan S. Brock (assistant engineer at bridge). The subsurface conditions at the bridge location are extreme. Much of Boston is underlain with clay, but the situation at the bridge is exacerbated by a fault which roughly follows the path of the Charles River itself. From a depth of approximately below existing ground, is a very dense till composed of gravel and boulders with a silt-clay matrix. Above that to approximately below the surface is Boston blue clay (BBC). Over this are thin layers of sand, gravel, and fill. The BBC is overconsolidated up to a depth of approximately . The original roadway and sidewalk stringers were of wood, with an approximately thick covering of asphalt on the sidewalk and a spruce wearing surface on the roadway. The exception was at the swing span, which was wide. This span was approximately long, and sat on a wooden pier. It was a double-cantilevered, electrically-driven structure also carrying a bridge caretaker's house. The bridge opened on September 1, 1891. The original cost of construction was $511,000, $ in current dollars. ==Maintenance and events==

, who jumped from the bridge in 1908 In 1898, bicycle lanes were installed next to each curb. A marker near the southeast end of the bridge memorializes one of Harry Houdini's "well known escapes", during which he jumped from the bridge on May 1, 1908. (Other sources give the date as April 30, 1908.) The bridge was declared unsafe in 1909, requiring all of the iron and steel to be replaced. The draw was elevated slightly and the trolley rails were replaced as well. When the Metropolitan District Commission (MDC) took control of the bridge in 1924, they rebuilt much of the bridge superstructure. They replaced the wooden stringers with steel "I" beams, topped wooden deck elements with concrete and brick, and replaced the street car rails. Heavy traffic at the Mass Ave and Memorial Drive intersection on the Cambridge end of the bridge led to the construction of an underpass in 1931. The bridge was formerly referred to as the "Xylophone Bridge" because of the sound its wooden decking made when traffic traveled over it. This decking was replaced in 1949 with concrete-filled "I-beam lok" grating topped with a thick bituminous wearing surface. At this time, all bearings were replaced, and the trolley car tracks were removed, as were granite blocks. The trolley car poles were reused for street lights. Ramps between the bridge and the under-construction Storrow Drive were added. Engineering study, 1971–1972 An engineering study was performed by the Metropolitan District Commission (later merged into the Department of Conservation and Recreation) in 1971–1972 due to complaints by bridge users of excessive vibration. The bridge was found to be understrength for its load. Before the final study was complete, the recommendation was to place a load limit of per axle and a total of per vehicle, or to restrict trucks to the interior lanes, where the bridge was stronger. A limit was imposed. Suggestions made included strengthening the existing structure by adding either struts or plates to make the existing four beams along the length of the bridge into a stiffening truss, or to replace the superstructure with a new one, made of either steel or concrete, which would be up to current standards. The price was estimated at US$2.5 million to US$3 million Superstructure replacement, 1980s After the failure of the Mianus River Bridge at Greenwich, Connecticut in 1983, the Harvard Bridge was shut down and inspected because it contained similar elements, specifically the suspended spans. Traffic was restricted to the inner two lanes due to the discovery of two failed hangers on span 14. A few days later, all trucks and buses were banned from the bridge. Structural modifications included an upgrade from four longitudinal girders to six of the same shape and replacement of a stairway with a handicapped pedestrian ramp on the Boston end of the bridge. Ramp "B", from southbound (Boston bound) bridge lanes to eastbound Storrow Drive, caused traffic to merge onto Storrow Drive from the left (high speed) lanes using a short acceleration lane, causing safety issues. The MDC requested elimination of this ramp. Compared to overall bridge traffic of 30,000 vehicles per day, traffic on ramp B was found to be low, approximately 1,500 vehicles per day with a peak of 120 vehicles per hour. The historic value of the bridge was considered significant, so the plan was to make the replacement superstructure appear similar, with similar railing and lighting. In order to document the pre-existing structure, a Historic American Engineering Record (HAER) would be prepared. Pier 12 was exhibiting inappropriate movement and was scheduled for reinforcement. The work would be done in two phases. Phase 1 would reinforce the downstream side of the bridge to allow MBTA bus traffic, and was expected to take 5 months. Most of this effort would be spent on the underside of the bridge and would not affect existing traffic. Phase 2 would replace the entire superstructure and was expected to take three construction seasons to implement. Cost was estimated to be File:Harvard Bridge, Spanning Charles River at Massachusetts Avenue, Boston ( Suffolk County, Massachusetts).jpg|Bridge viewed from the upstream Cambridge side in 1985. Construction barrels restricting traffic from the outside lanes, and general wear and tear are visible (click on image to enlarge) File:Harvard Bridge from Cambridge, 2009.jpg|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. File:Underside, centerline, 1985.jpg|Underside of the bridge in 1985. Image shows how the bridge was originally built, and later modified, but before the superstructure was replaced. File:Harvard Bridge, centerline, looking north, 2009.jpg|Underside of the bridge in 2009. Image shows how the replacement superstructure was built, with six longitudinal girders, different bracing, etc. Subsequent events In the fall of 2014, the Charles River Conservancy announced that an anonymous donor would fund an upgrade of the street lights for both the roadway and both sidewalks on the bridge. The new roadway and aesthetic lighting was installed in 2015, highlighting the smoot marks along the sidewalk. The design was selected after a competition won by Miguel Rosales of Rosales + Partners. The light posts were located apart. "It will provide safe lighting for pedestrians and drivers, and the elements of design on the bridge will be pulled out and emphasized. It will become a really beautiful bridge," said Renata von Tscharner, founder and president of the Charles River Conservancy. Separated bicycle lanes In November 2021, to improve bicycle safety, MassDOT initiated a separated bicycle lane pilot on the Harvard by placing cones to create two wide bicycle lanes. This reduced general purpose lanes from four to two over the bridge. Despite some hiccups involving vandalism, the pilot was deemed a success in the Fall 2022. MassDOT went on to hire Toole Design Group to engineer flex-post separated bicycle lanes, bus priority lanes, and new traffic signal phasing for the corridor. These changes were implemented just before 2023, and have been in place since. To this date, the Harvard Bridge remains one of the most popular cycling routes in New England, with an average of over 1,000 bicyclists in each direction per day. ==Smoots==

The Harvard Bridge is marked off in an idiosyncratic unit of measure, the smoot. In 1958, members of the Lambda Chi Alpha fraternity at MIT measured the bridge's eastern sidewalk by using that year's shortest pledge, Oliver Smootnominally, tallas a measuring stick. Years after this stunt, Smoot became president of the American National Standards Institute (ANSI), and later president of the International Organization for Standardization (ISO). Markers painted at intervals give the bridge's length 364.4 smoots long, "plus one ear". Originally this read "plus or minus one ear"representing measurement uncertaintybut over the years the words "or minus" disappeared. The marks are repainted periodically by members of the fraternityoriginally surreptitiously and later openly. Officials' original determination to omit the smoot markings from the reconstructed bridge, and to scrupulously prevent the fraternity from repainting them, evaporated when it was realized that police routinely used the smoot marks as reference points in accident reports. The nominal length of 364.4 smoots (from two designated points at the bridge's ends) corresponds to about 2030 feet or 620 m, somewhat less than the bridge's published length of . corresponds to 387.7 smoots ± one ear. ==See also==