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38-856: The Maurice J. Tobin Memorial Bridge (formerly the Mystic River Bridge ) is a cantilever truss bridge that spans more than two miles (3.2 km) from Boston to Chelsea over the Mystic River in Massachusetts , United States. The bridge is the largest in New England . It is operated by the Massachusetts Department of Transportation and carries U.S. Route 1 . It was built between 1948 and 1950 and opened to traffic on February 2, 1950, replacing

76-423: A balanced cantilever ; when they attach to a solid foundation, the counterbalancing arms are called anchor arms . Thus, in a bridge built on two foundation piers, there are four cantilever arms: two which span the obstacle, and two anchor arms that extend away from the obstacle. Because of the need for more strength at the balanced cantilever's supports, the bridge superstructure often takes the form of towers above

114-505: A bridge that could handle differential settlement of the foundations. Engineers could more easily calculate the forces and stresses with a hinge in the girder. Heinrich Gerber was one of the engineers to obtain a patent for a hinged girder (1866) and is recognized as the first to build one. The Hassfurt Bridge over the Main river in Germany with a central span of 124 feet (38 metres)

152-645: A new freight terminal built on filled land in the Mystic River between the two channels. After a legal battle with the Lynn and Boston Railroad about the right to cross its tracks , the B&;L extended the branch across the Mystic Bridge, allowing ships to dock without passing through any bridges. As the B&L and its successor Boston and Maine Railroad (B&M) expanded Mystic Wharf in the 1880s, replacing

190-522: A wedding party died when they drove onto the Charlestown end of the closed bridge and fell into the river at the open north draw. The north draw and the north section of the viaduct were removed in 1954. A new street, Terminal Street, opened on August 21, 1956, to serve the Mystic Wharf; the old south draw was closed at that time and soon removed. A new fixed bridge was built near the alignment of

228-443: Is available to support the tension in the upper chord of the span during construction, usually limiting this method to the spanning of narrow canyons. World's longest cantilever bridges (by longest span): Retractile drawbridge A retractile drawbridge is a rare type of moveable bridge in which the span is pulled away diagonally on rails. It is a variant of the retractable bridge . Only four examples are known to exist in

266-747: The Eastern Massachusetts Street Railway (successor to the Lynn and Boston) to be maintained during construction. However, the Eastern Mass instead operated buses between Chelsea Square and Haymarket Square via the Meridian Street Bridge and the newly opened Sumner Tunnel under a permit issued just two days prior. The bridge reopened on December 23, 1935, without streetcar tracks; the Eastern Mass continued its bus operations. The Boston Elevated Railway began Chelsea Square– City Square bus service over

304-465: The Navajo Bridge ) are built using pure cantilever spans from each side, with neither falsework below nor temporary supporting towers and cables above. These are then joined with a pin, usually after forcing the union point apart, and when jacks are removed and the bridge decking is added the bridge becomes a truss arch bridge . Such unsupported construction is only possible where appropriate rock

342-435: The 19th century understood that a bridge that was continuous across multiple supports would distribute the loads among them. This would result in lower stresses in the girder or truss and meant that longer spans could be built. Several 19th-century engineers patented continuous bridges with hinge points mid-span. The use of a hinge in the multi-span system presented the advantages of a statically determinate system and of

380-506: The New England Gas and Coke Company prepared to open its new plant upstream, a further widening of the north draw became necessary to accommodate Dominion Steel and Coal Corporation ships serving the plant. Henry Melville Whitney offered to pay $ 40,000 on behalf of the company to secure a width of 75 feet (23 m); however, the city instead chose a 60-foot (18 m) width. Preliminary work began in late 1899. A temporary bridge

418-415: The action of the outer foundations. Cantilever Bridge.—A structure at least one portion of which acts as an anchorage for sustaining another portion which extends beyond the supporting pier. A simple cantilever span is formed by two cantilever arms extending from opposite sides of an obstacle to be crossed, meeting at the center. In a common variant, the suspended span , the cantilever arms do not meet in

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456-519: The bridge began during his term as governor (1945–1947). Tobin went on to serve as Secretary of Labor under President Harry Truman before he died in 1953. Instead of eliminating the tolls, the southbound tolls were increased to 25 cents to cover the closing of the Northbound toll plaza in the 1980s. Starting in the early 1990s the tolls increased sharply to help pay for the Big Dig . Legislation

494-552: The bridge deck, repair steel, and paint a portion of the bridge. The work ran April through November in 2018, 2019, and 2020. The current bridge has not been spared having numerous incidents during its 50 plus year lifespan. In 1973, a gravel truck traveling over the lower deck crashed into a support, collapsing the upper deck onto the truck and killing the driver. Later that year, the bridge reopened after more than two months of repair. On January 4, 1990, racial hoaxer and double murderer Charles Stuart committed suicide by jumping from

532-500: The bridge on July 2, 1936. The new bridge was originally operated by the Mystic River Bridge Authority. The bridge, according to the statute enacted May 23, 1946, would be turned over to the Massachusetts Department of Public Works once the $ 27 million in bonds used to finance the bridge's construction was retired. The bridge would then become part of the state highway system to be maintained and operated by

570-629: The bridge. Suicides and attempted suicides have been an issue for authorities in general as the design and weight of the bridge makes it impossible to add suicide prevention devices. MassDOT employees are thus trained to monitor security cameras and watch for any vehicles that stop on the bridge for whatever reason. Cantilever bridge The steel truss cantilever bridge was a major engineering breakthrough when first put into practice, as it can span distances of over 1,500 feet (450 m), and can be more easily constructed at difficult crossings by virtue of using little or no falsework . Engineers in

608-423: The center; instead, they support a central truss bridge which rests on the ends of the cantilever arms. The suspended span may be built off-site and lifted into place, or constructed in place using special travelling supports. A common way to construct steel truss and prestressed concrete cantilever spans is to counterbalance each cantilever arm with another cantilever arm projecting the opposite direction, forming

646-504: The department free of tolls. Operation of the bridge was turned over to the new Massachusetts Port Authority in 1956. The Chelsea Bridge originally remained intact; the southern section remained open as truck access to Mystic Wharf, while the northern section was closed to traffic but still carried a water main across the Mystic River. State funding for a replacement water tunnel was approved in August 1950. On January 28, 1951, six people in

684-453: The former Chelsea Bridge . The 36-foot (11 m)-wide roadway has three lanes of traffic on each of the two levels with northbound traffic on the lower level and southbound traffic on the upper level. The bridge is a three-span cantilevered truss bridge at 1,525 ft (465 m) in total length. The center span is longest at 800 ft (240 m) and the maximum truss height is 115 ft (35 m). There are 36 approach spans to

722-574: The former cash toll rate. This inaugurated a 2½ year process by MassDOT which converted all of the toll roads and bridges throughout the Commonwealth to automatic open road tolling . In 2016, the $ 2.50 southbound toll was replaced with $ 1.25 tolls in both directions, with a 30-cent surcharge for pay-by-mail. In September 2017, the Massachusetts Department of Transportation announced a three-year $ 41.6 million project to restore

760-570: The former south draw in 1982 as part of a project to remove trucks from neighborhood streets in Charlestown. It provides only 12 feet (3.7 m) clearance above the water, as the only vessels using the Little Mystic Channel were recreational boats using a 1970s-built boat ramp. In 1967, the Mystic River Bridge was renamed in honor of Maurice J. Tobin , former Boston mayor and Massachusetts governor. Construction of

798-648: The foundation piers. The Commodore Barry Bridge is an example of this type of cantilever bridge. Steel truss cantilevers support loads by tension of the upper members and compression of the lower ones. Commonly, the structure distributes the tension via the anchor arms to the outermost supports, while the compression is carried to the foundations beneath the central towers. Many truss cantilever bridges use pinned joints and are therefore statically determinate with no members carrying mixed loads. Prestressed concrete balanced cantilever bridges are often built using segmental construction . Some steel arch bridges (such as

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836-444: The grade crossings. The B&M was to pay 65% of the cost, the Lynn and Boston Railroad 5%, and the state 30% (of which part would be in turn paid by Boston and Chelsea). Negotiations between the B&M, the Lynn and Boston, and the cities of Boston and Chelsea took place in 1893 over plans to raise the street onto a viaduct over the rail yard. The B&M was willing to build a viaduct with a wooden roadway 40 feet (12 m) wide, but

874-472: The largest bridge span in New England – opened on May 28, 1913. The 1,400-short-ton (1,300 t) span rotated on 64 wheels on a 44-foot (13 m) diameter circular rail. It was 363 feet (111 m) long and 60 feet (18 m) wide, and could rotate to provide two 125-foot (38 m)-wide channels large enough for oceangoing ships. As part of the $ 425,000 project (equivalent to $ 9,600,000 in 2023),

912-437: The middle section of the bridge with a roadway on filled land, the grade crossings became a significant inconvenience and hazard to bridge traffic. The railroad's construction of transatlantic port facilities, including a grain elevator and coal depot, along with additional crossings of the bridge road brought the issue to a head in 1892. That June, the state legislature passed an act authorizing Chelsea to pursue elimination of

950-417: The north and 32 to the south. The roadway is seven lanes wide between the shortest (439 ft; 134 m) span and the center to accommodate the now-unused toll plaza . The northbound toll plaza was closed in the 1980s; the southbound toll plaza was closed on July 21, 2014. [1] and replaced by open tolling or pay by license plate . [2] [3] Early transport between Boston and Winnisimmet (later Chelsea)

988-502: The north draw was restricted to vehicles under 6 short tons (5,400 kg) except for streetcars, using only one lane in each direction. The century-old drawtenders' house nearly collapsed into the river on July 23, 1934, as piles supporting it sank into the riverbed. A $ 292,222 contract (equivalent to $ 5,200,000 in 2023) for repairs to the north span was issued on October 26, 1934. The bridge closed to all traffic effective January 14, 1935. Initial plans had called for streetcar service by

1026-476: The old grade, with a 45-foot (14 m)-wide roadway and 8-foot (2.4 m)-wide sidewalk. Masonry piers spaced 70 feet (21 m) apart supported the iron viaduct, which cost $ 600,000 (equivalent to $ 14,200,000 in 2023) to construct. A perpendicular ramp led from the viaduct to the rail yard below. As part of the project, the north draw span was replaced by a retractile drawbridge and widened by 8–10 feet (2.4–3.0 m) to just under 45 feet (14 m). As

1064-449: The other parties insisted on a 50 feet (15 m)-wide roadway with a granite deck. A temporary south span and roadway opened on May 1, 1894, allowing construction of the viaduct to begin. This was closed to all but streetcar traffic on May 1, 1895. Streetcars began using the new viaduct on August 4, 1895, and it opened to general traffic on December 29. The viaduct was 2,777 feet (846 m) long and raised about 20 feet (6.1 m) above

1102-435: The permanent span (equivalent to $ 7,500,000 in 2023) was issued on April 26, 1922, and construction began on May 2. The new bridge opened on April 21, 1924. It was 365 feet (111 m) long, with a four-leaf bascule draw 119 feet (36 m) long and 61 feet (19 m) wide, widening the channel to 75 feet (23 m). By early 1934, the north section of Chelsea Bridge was in need of repairs. On June 27, 1934, traffic on

1140-577: The portion of the bridge within Chelsea, including the north draw. The Boston portion was damaged by a fire on September 7, 1887. Electric streetcars replaced the horsecars on the bridge in the early 1890s, with all-electric service effective March 13, 1893. The Boston and Lowell Railroad (B&L) purchased the Mystic River Railroad, an unbuilt paper railroad , in 1871. It constructed the line from Milk Row station around Charlestown to

1178-431: The structural principles of the suspended span cantilever by sitting in chairs and supporting their colleague, Kaichi Watanabe , in between them, using just their arms and wooden poles. The suspended span, where Watanabe sits, is in the center. The wooden poles resist the compression of the lower chord , while the outstretched arms support the tension of the upper chord. The placement of the brick counterweights demonstrates

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1216-505: The wooden pile approaches were raised to eliminate a slope from the Charlestown viaduct. The city planned to replace the south draw span shortly afterwards at a nearly equal cost. On March 14, 1914, the 230-short-ton (210 t) temporary span from the north draw was moved in one piece – using the tide to lift the span on lighters – to serve as the new temporary south draw. The temporary span, with sharp reverse curves at both ends, remained in use longer than planned. A $ 521,830 contract for

1254-574: Was 275 feet (84 metres) deep and took full advantage of the fact that falsework, or temporary support, is not needed for the main span of a cantilever bridge. The Forth Bridge is a notable example of an early cantilever bridge. This bridge held the record for longest span in the world for twenty-nine years until it was surpassed by the Quebec Bridge . The engineers responsible for the bridge, Sir Benjamin Baker and Sir John Fowler , demonstrated

1292-631: Was by the Winnisimmet Ferry . In 1803, the Salem Turnpike was extended across the Mystic River to Charlestown, where the Charles River Bridge then connected to downtown Boston. The new Mystic River bridge (Chelsea Bridge) had two draw spans and cost $ 53,000 (equivalent to $ 1,310,000 in 2023) to construct. The Boston and Chelsea Railroad opened a single horsecar track over the bridge on November 20, 1858. The toll

1330-550: Was completed in 1867 and is recognized as the first modern cantilever bridge. The High Bridge of Kentucky by C. Shaler Smith (1877), the Niagara Cantilever Bridge by Charles Conrad Schneider (1883) and the Poughkeepsie Bridge by John Francis O'Rourke and Pomeroy P. Dickinson (1889) were all important early uses of the cantilever design. The Kentucky River Bridge spanned a gorge that

1368-490: Was dropped on November 9, 1869, when the bridge and turnpike became state property. The Boston portion of the bridge was rebuilt in 1877, with a new iron draw span, while the Chelsea portion was also repaired. The Lynn and Boston Railroad (successor to the Boston and Chelsea Railroad) ran a pair of horsecar tracks across the bridge. In 1880, Chelsea paid Boston $ 25,000 (equivalent to $ 678,000 in 2023) to permanently maintain

1406-450: Was funded by the gas company ($ 14,000) and the Lynn and Boston ($ 7,000). A contract for $ 21,471 for the construction of the new draw span was issued on February 26, 1900. The new span opened on September 25, 1900, with a total cost around $ 75,000 (equivalent to $ 2,259,000 in 2023) Another replacement of the north draw span began in early 1912, with the temporary bridge completed that August. The new steel truss swing span – claimed to be

1444-478: Was passed to transfer the bridge from Massport to the new Massachusetts Department of Transportation , effective January 1, 2010. On the morning of July 21, 2014, the bridge's tollbooths were closed and eventually removed for an all-electronic and cashless tolling system, and from that point on all toll charges are paid for via either E-ZPass at the current rate, or "pay-by-mail" where an invoice will be sent to motorists’ homes via license plate number recognition at

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