April 2018 April 2018 - Page 12

Region 1 Spring Assembly – Tarrytown, NY “The New NY Bridge Project” By: Sarah Dinwoodie I attended my first Region 1 Assembly April 21-22 in Tarrytown, NY. It was a great experience meeting ASCE representatives from across New England and New York and learning about Governors and the larger structure of ASCE. During the Assembly, we heard a presentation from Thomas McGuinness, P.E. a Construction Compliance Engineer from the New York State Thruway Authority (NYSTA) on the construction of the New NY Bridge Project. (Due to security we were not able to take pictures during his presentation and due to construction we did not tour the bridge.) structural rehabilitation of the 1950’s structure and no structural redundancy to protect the bridge in case of a catastrophic event. In addition, there were no bike or pedestrian lanes, so traffic over the bridge was limited to vehicles. Old vs. New The Tappan Zee Bridge had one span with seven 11-foot lanes. It was about 87 feet wide. The New NY Bridge has two independent spans with a cable staged main span. Both bridges span 3.1 miles with approximately 2.7 miles of approach. The New NY Bridge will feature all electronic tolling and a 12-foot shared use path with six overlooks. The New NY Bridge will have two spans together containing eight lanes, four shoulders, two bus lanes, and a shared use path. The northbound span will be able 96 feet wide and the southbound span will be about 87 feet wide. Photo Credit: https://www.aecom.com/projects/tappan-zee-bridge/ Former Tappan Zee Bridge The New NY Bridge is replacing the existing Tappan Zee Bridge, which spans 3.1 miles across one of the widest points of the Hudson River connecting South Nyack in Rockland County with Tarrytown in Westchester County. After four years of construction, the New NY Bridge has opened the first span to traffic. The northbound span is now being used for two-way traffic. Why a New Bridge? The Tappan Zee Bridge was designed and constructed from 1952 to 1955 with a design capacity of 100,000 vehicles per day. Before this project began, the bridge was averaging 140,000 vehicles per day. The Tappan Zee Bridge had no emergency lanes or shoulders and had accident rates two times the NYSTA’s average rate. There was a significant cost associated with the Photo Credit: https://finance-commerce.com/2017/08/first-span-of-4b-new-york-bridge- opening/ Construction of the two new spans adjacent to the Tappan Zee Bridge Complications One of the major complications with the project was tying into the land on either side of the Hudson. To reduce the amount of land taken by eminent domain, the NYSTA could only construct one span while the Tappan Zee was still in use. The NYSTA construction both spans simultaneously until they were approximately