Echo Bridge

Mr. Mek and I were visiting a friend. As we left, we asked if she knew of any interesting bridges near by. She guided us to this spot. We?ve driven near it so many times but never knew it was here. Now we know...

This beautiful structure is known as Echo Bridge. It extends over the Charles River between Cook's Bridge and the Boylston Street span. Its construction by the Boston Water Board was started in the spring of 1876 and completed in November 1877 at a cost of $200,000. During its construction no accident occurred to a workman or to the machinery.

The bridge is 500 feet in length and consists of seven arches, five of 37 feet span and one (over Ellis Street) of 38 feet. The seventh and largest arch, which spans the river is said to be the second in size on this continent and one of the largest stone arches in the world. At the time of construction its size was exceeded only by the Cabin John Bridge in Washington, D.C. It is segmental in form, 130 feet in span, with a radius of 69 feet. The crown is 51 feet above the usual surface of the water and the top of the bridge 70 feet above the river. The keystone is five feet in depth with the archstones increasing to six feet at the base forming a very heavy arch, and the pressure upon the foundation is about 2,900 tons - or about 16 tons to the square foot. The foundations of the entire bridge are in solid rock.

The timber framework upon which the arch was built rested upon five points of support in the bed of the river and demanded about 110,000 feet of spruce, oak and hard pine timber in its construction. The settling of this framework which was caused by the weight of the archstones during construction was only about, two inches. To one standing beneath it the arch has a very slender and beautiful appearance, tapering from 22 feet at the base to 18 feet in width at the crown. There is a remarkable echo within the arch with the human voice being rapidly repeated upwards of 15 times and a pistol shot 25 times.

The inside section of the conduit carried within the bridge is equal to a circle eight and a half feet in diameter, its width is nine feet and height seven feet, eight inches. The inclination of the conduit is one foot per mile and its capacity, when filled to high water mark, is 80,000,000 gallons in 24 hours. At each end of the bridge were two large iron doors lying flush with the surface of the granite topping. When opened they revealed a flight of iron rungs leading down into the conduit where a boat was moored. This was used periodically to inspect the conduit. On occasion a privileged few were allowed to go along on these inspection cruises. King's Handbook of Newton records the adventures of one of the fortunate ones, Mary Blake.