Department of Civil, Structural and Environmental Engineering

Trinity College Dublin

The Schoharie Creek Thruway bridge collapse

Group 18Karen McMorrow

David O’BrienClare Whitely

Introduction

•Design Started in 1949

•Completed in October 1954•165m span comprising of 5 simple spans

• 165m long bridge comprising of 5 simple spans

•1955: 100 Year Flood

•Collapsed in 1987

The Collapse•The bridge collapsed during an estimated 50year flood in 1987

•Pier 3 collapsed first

•Followed instantly by spans 3 and 4

•This led to the collapse of pier 2 and span 2

•Finally 2 hrs later, Pier 1 and Span 1 shifted.

PIER 1 PIER 2 PIER 3 PIER 4

Flow

EastAbutment

SlopedEmbankment

RiprapSlopedEmbankment

West Abutment

NORTH

110' 120' 110' 100'SPAN 1100'

SPAN 2 SPAN 5SPAN 4SPAN 3

Figure 2 - Schematic plan of bridge ( after "Collapse," 1987 )

PIER 1 PIER 2 PIER 3 PIER 4

Flow

EastAbutment

SlopedEmbankment

RiprapSlopedEmbankment

West Abutment

NORTH

110' 120' 110' 100'SPAN 1100'

SPAN 2 SPAN 5SPAN 4SPAN 3

Figure 2 - Schematic plan of bridge ( after "Collapse," 1987 )

Reasons For Failure

Scour: The removal of sediment from a streambed due to water erosive action

Influencing Factors

•Shallow footings

•Sheet-piles removed

•Riprap was not adequate

•Foundations on erodible soil

•Could not resist scour

Lessons Learnt

•Always perform regular maintenance and inspections

•Need for clear design objectives

•Sheet piling should have been left in place

•Importance of footing depth

•Design for rare events

Conclusion•10 lives were lost in this tragedy, this could have been prevented with regular inspections, better

communication and adequate erosion protection