Norwich bulletin., 1922-07-19

Just about a year from the time work on the new sub-structure was com menced. the new 21s foot highway draw bridge over the Mystic river at Mystic Is to be formally opened today (Wedhes- day) with celebration of the event.
 Three. other bridges have preceded the new one at this point. but it will be years again before anw more changes will need to be made as the new bridge is of a thoroughly modern type and careful caiuculation were made that it should be adequate to take care of traffic for years to come.
 The new bridge has been in use for the public since it was officially opened for traffic July 12 at 4.25 p. m, but it was used for several weeks before that by foot passengers for travel at their own risk.
 The Groton span of the bridge is 6s feet, tower span 2S feet, lift span SS feet and Stonington span S5 feet.
 The roadway is SS feet wide with two six foot sidewalks on each side and single track for trolleys in the center.
 The bridge is of a type that is the first of it's kind in the United States. It is known as the Brown balance beam light bridge The lift proper is sS feet long and when fully open gives 75 feet of clear channel. To balapce this mass of steel and concrete weighing 150 tons when in operation, two, two hundred ton concrete centarweights are used and that it is finely balanced may be realized by the fact that but about one-half of the avail able power is necessary to raise the left in the space of about 35 seconds. The lift is governed by a 25 horsepower com- pressor.
 To prevent anyone going on to the bridge when the lift is to be operated a warning bell and stop sign electrically operated are at each end and in addition four safety gates each individually ope- rated from the tower are used
 In preparation for beginning the work on the sub-structure. temporary bridge had to be built a few rods north of the old bridge and has been in use for high way and foot passenger purposes. The real bridge work was started July 10. 1921, when the sub-structure was com menced. Four coffer dams had to be built for the four piers on the Groton side of the river and four for those or the Stonington side. After placing the | crossbeams joining the abdtments, the 1 lenders were built: this work filling the {, time up to April. 1922, when the Ameri- : can Bridge company began tnelr work on | tural steel used weighs about 500 tons A. R. Collier has been the resident en- gineer in charge of the work.
 At the same time the bridge was beins i built new roadways and sidewalks were i built on both the Groton and Stoningtor side of the river.
 The first bridge over the Mystic river was operated by drawing the span over rolls from over the channel by means of horses. Late In the 50s or early sos a new bridge WEE erected which swung from the center being operated by man power ! by means of long pole. In 1886 third bridge was built which was used unti the | Groton and Stonington Trolley company 1 opened the line from Groton to Westerly when the structure thas everyone remem
 bers was built. This was never entireiy satisfactory. as more or less trouble wa ! encountered by the abutments and pier settling which caused the bridge to 1am