The Lawrence Bridge was built and chartered in 1854 for the purpose of accommodating the traffic between Lawrence and North Andover and to avoid the railroad crossing. It followed Union Street over the Merrimack River. It opened for business November 8th, 1855, the owners celebrating the event that evening with dinner at the Franklin House. The Lawrence Bridge Company ran the bridge as toll bridge until August 7, 1868, at 9:00 AM, when the bridge became free as a public highway. The city paid the larger part of the value assuming the care of the bridge under the county commissioner’s award. Nicholas Chapman performed the function as Keeper of the Lawrence Bridge during the entire time the company collected tolls. Every month he collected the fees and turned them in to George D. Cabot, the manager of the Lawrence Gas Company. The Lawrence Bridge was destroyed by fire in 1887 and rebuilt in iron 1888 by the Boston Bridge Works. It was built as a five-span through truss bridge with George L Vose as the engineer with It is a five riveted, double-intersection Warren through truss spans and is 609.9 ft. in length. At present it is known as the Union Street Bridge or the Duck Bridge (in honor of the mill nearby the produced duck fabric) and enables 29,000 vehicles to cross every day.
Boston Bridge Works operated an office at 70 Kilby Street from 1888-1890. The proprietor was D. H. Andrews and there was a notation that the Works were located in East Cambridge. I do know that Boston Bridge Works was around until at least the 1930s as they constructed several bridges in Boston.