The Civil Engineering Department has awarded the Bass Rive Bridge senior project an Overall Excellence in a Senior Design Project award. The following students were recognized: Nicholas Izzo (team leader and geotechnical design), Catherine Brabston (geotechnical design), Michael Berti (structural design), Kristen Harding (structural design) and Matthew Della-Croce (hydrological design).
The Bass River Bridge Project is part of the New Jersey Turnpike Authority’s widening project along the Garden State Parkway from Interchange 30 to Interchange 80. A new three lane, multi-girder bridge over the Bass River is being proposed in the northbound direction. It will be located adjacent to the existing Bass River structure, which will be rehabilitated with the intent to carry all traffic in the southbound direction. The design goal of the project is to provide a geotechnical, hydrologic, and structural design for the new Bass River Bridge.
The geotechnical portion included a soil analysis and the design of the embankments, pier, and abutment foundations. Nine soil layers including 3 cohesive layers and 6 granular layers were identified. Of the cohesive layers, the top cohesive layer is organic and governed the geotechnical designs. Bridge approach embankments were designed as MSE walls due to right-of-way constraints. An analysis of the MSE wall resulted in an estimated failure in global stability, sliding, and soil bearing capacity. Soil improvements in the form of column supported embankments were designed along 450 feet of the Northern approach and 900 feet of the Southern approach. One foot diameter vibro-concrete columns (VCC) were used throughout with spacing ranging from 6-10 feet. A load transfer platform was also designed with the number of layers ranging from 3-5 layers. Pier and abutment foundation designs included 18” concrete piles in a layout of 3×10 for the main piers, 4×7 for the large abutment, and 3×5 for the small abutment. These piles were analyzed for geotechnical, structural, and group capacity as well as drivability. These provided for an approximate minimum tip elevation of -80.0 feet for the piers and -70.0 feet for the abutments. These depths provided for an ultimate capacity of 1450 and 1300 kips for the piers and abutments, respectively.
The hydrologic team delineated a watershed and found that the watershed area was 13.13 square miles. Snyders Method, SCS Regressional Approach, and SCS Segmental Approach were used to calculate the lag times of the watershed, which were 9.05 hours, 6.18 hours, and 1.8 hours, respectively. The lag times were used to determine the most critical peak flow of the watershed using HEC-HMS. SCS Segmental Approach resulted the most conservative peak flow of 4406.5 cfs. The opening of the bridge was found to be adequate for a 24-hour, 100 year storm using HEC-RAS. HEC-RAS was also used to find a maximum scour of 6.43 feet on the piers.
The structural design consisted of a load analysis and the selection of a steel main span interior girder and bridge deck. Seven girders, spaced at 9 feet center-to-center, and a 9 ½ inch reinforced concrete deck were chosen to support the loads of the bridge. Diaphrams were selected according to NJDOT standards and are provided at every 20 feet along the length of the bridge. With this design, Virtis/Opis software was utilized to check the adequacy of the structure. The structural portion concluded with the design of the splices, shear studs, and the reinforcement within the pier caps.