Engineers at Steere Engineering performed bridge design and initial load ratings for the largest infrastructure project in Rhode Island history. The IWay project relocated the junction of two major interstate highways, I-95 and I-195 in Providence, bringing them up to modern standards and improving traffic flow while minimizing the impact to the public.
The original I-95 – I-195 interchange was built during the inception of the interstate highway system in the 1950’s and featured many substandard highway features as well as severe deterioration. The project focused on replacing the main line of I-195, with the Providence River Bridge, a series of seven ramp bridges, and six highway/overpass bridges. The majority of Steere Engineering’s senior staff worked together on the project from design through construction, including the company founder and president, Patricia Steere who acted as engineer-of record for most of the bridges. The project also featured thousands of feet of concrete and MSE retaining walls, complex substructures including integral piers, and a variety of foundation types including drilled shafts, pile supported, and spread footing.
The Providence River Bridge, also known as the IWAY Bridge, is a seven-span, 1,250-foot-long bridge carrying I-195 over the Providence River. The main span is a 400-foot-long network arch bridge, the first in the United States. Based on Steere’s research into network arch bridges, it was decided to use the network arch cable arrangement to reduce the moments in the arch tie, and reduce their cross sections to obtain a lightweight and structurally efficient design. This efficiency allowed for the innovation construction approach of constructing the bridge on land and floating it into position. The bridge was modeled using GT Strudl and designed in accordance with the AASHTO Standard Specifications for Highway Bridges (17th Edition) (AASHTO) code. The tie was designed to be internally redundant and used high performance steel to increase the fatigue resistance.
The seven ramp bridges are multi-span steel trapezoidal box girder bridges with the longest ramps over 1,500 feet in total length. Spans are up to 250 feet long. The bridges feature three integral pier caps and uneven span lengths due to the congested urban site where they were built. High performance steel was used for the fracture critical integral pier caps as well as the two-girder bridges. The bridges were modeled in three dimensions using a combination of SAP2000 and DESCUS. They were designed in accordance with AASHTO for an HS-25 loading and seismic loads.
All the bridges built under the contract were load rated in accordance with the LRFR methodology of the AASHTO Manual for Bridge Evaluation and RIDOT Guidelines. The bridges were modeled using SAP2000, GTStrudl, BRASS Girder LRFD, and Virtis and were rated for HL-93, as well as the eight additional legal load vehicles, and seven permit vehicles required by the RIDOT guidelines. Bridges were rated for strength and for fatigue when required.
The project has received numerous awards including the American Council of Engineering Consultants- Massachusetts (ACEC-MA) Grand Conceptor Award.
Design Completion: 2012
Reference: David Fish, PE, Acting Chief Engineer Construction Completion: 2013
Project Cost: $610 Million