ACCELERATED DESIGN-BUILD REPLACEMENT OF SEPTA'S CRUM CREEK VIADUCT

摘要

Built in 1895, the Crum Creek Viaduct rises nearly 100 feet above Crum Creek and spans a length of more than 915 feet. Emergency repairs performed in 1983 were intended to extend the life of the bridge by 25 years. Thirty-two years later, the Crum Creek Viaduct had reached the end of its useful life and required replacement. Faced with the need to replace the structure while minimizing impact to its steadily increasing ridership and service requirements, SEPTA employed innovative contracting and construction processes to replace the structure during an eleven (11) week outage window in the summer of 2016 during which SEPTA provided alternate bus service. The Crum Creek Viaduct Replacement Project is a unique accelerated bridge design/build project that replaced a bridge on an existing rail alignment. The new steel girder closed deck bridge has five spans and is 735' long with a maximum span length of 157'. A real-time bridge monitoring system was installed on the existing structure to monitor movements of the existing in-service bridge as well as the stability of the steep slopes during construction. Innovative solutions were employed to design and deliver the new bridge on-time with a fast-paced schedule, which only permitted an eleven-week rail shut down for replacement. The new bridge was assembled on one side of the existing bridge supported by new straddle bents built under the existing bridge while the existing bridge remained in full operation. A lateral slide Accelerated Bridge Construction technique was used to move the new bridge into place. Results include budget savings, reduced customer inconvenience, and increased productivity by employing and coordinating the design-build construction team with in-house work groups.