For the densely populated state of New York the Tappan Zee bridge, crossing the Hudson river north of the city of New York constitutes a vital artery for residents, commuters, travellers and commercial traffic. The bridge opened to traffic in 1955 and was at that time designed for a humongous number of 100.00 vehicles per day. In the past decades, daily bridge traffic has grown to about 138,000 vehicles. Hundreds of millions of dollars have been spent to maintain the structure. Heavy traffic and lack of emergency shoulders can create unsafe driving conditions on the bridge and lead to frequent congestion and frustration for motorists.