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CROSS Safety Report

Fall of material from bridge soffit

Report ID: 549 Published: 1 July 2016 Region: CROSS-UK

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Overview

Several reports about materials falling from bridges have been sent by a bridge owner.

Key Learning Outcomes

For asset owners and managers:

  • Regular inspections and maintenance can help keep a structure safe and to detect any obvious safety issues

  • Where defects are identified on ‘grey’ assets then liaison between liable parties should be carried out to ensure risks are managed appropriately

  • Be aware that owners of structures over and under roads and railways have an obligation to inspect and maintain these structures in accordance with the procedures set out by the operator of that infrastructure

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Reports about materials falling from bridges have been sent by a bridge owner and some are given below:

Falling Concrete – issue one

A member of the public reported that he was hit by falling concrete from an underbridge (Figure 1). Responsibility for the bridge was in a ‘grey’ area between two owners and the organisation concerned recommended that clear and transparent demarcation is required for all assets where maintenance liability is shared. Where defects are identified on grey assets then liaison between liable parties should be carried out to ensure risks are managed appropriately.

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Figure 1: spalling concrete

Masonry and concrete falling from bridge – issue two

A member of the public contacted authorities to report masonry falling from a bridge (Figure 2). It was found that weathering in the form of repeated freeze/thaw cycles was responsible. This is a high bridge in an urban area with a pavement underneath so people could have been hit by debris. In a separate, incident inspectors found loose concrete spalling from the arch of a bridge soffit.

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Figure 2: spalling masonry

Concrete encasement falling from bridge – issue three

A 4.5m length of concrete encasement was detached from a bridge soffit and fell onto a public area (Figure 3). Fortunately, no one was injured, but clearly the incident could have caused a fatality. The root cause was corrosion of the reinforcement after cracking of the concrete, but differential temperature between the metal beam and concrete had a part to play in the final failure – around that time a temperature of 34°C was recorded.

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Figure 3: fallen concrete encasement

Missing bolts – issue four

A report was received from a local authority about a fracture in a footway attached to the side of a main bridge structure. The footway was supported on cantilevered members and it was found that of the 8 bolts holding these in place 4 bolts had fallen out (Figure 4).

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Figure 1: missing bolts

Expert Panel Comments

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Expert Panels comment on the reports we receive. They use their experience to help you understand what can be learned from the reports. If you would like to know more, please visit the CROSS-UK Expert Panels page.

CROSS has reported many times on the dangers of falling material. It has led to injury and death. See for example Confidential Reporting on Structural Safety for Scottish Buildings. It is a reality that the nation has a vast portfolio of ageing property and infrastructure which will deteriorate for a variety of reasons. Standard hazards are both weakening and material falling with obvious danger, the risk being most acute when people might be hit. All owners have a responsibility to manage the risk and that starts with an awareness of the hazard followed by condition inspection to assess the likelihood.

All owners have a responsibility to manage the risk and that starts with an awareness of the hazard followed by condition inspection to assess the likelihood

Can joint ownership lead to confusion over responsibilities?

Joint ownership (issue one) has caused many problems – often one party assumes that the other party is maintaining the asset and/or is responsible for parts of it. There have been cases where one shared owner modified a structure, not realising the changes were unsafe. In another case an owner carried out no inspections or maintenance, so it was fortunate that the operator of the infrastructure underneath, who did not know it was not their structure, inspected and maintained it.

In a similar case no inspections were carried out due to misunderstanding about ownership. This was a newer structure such that significant deterioration would be obvious but, nonetheless it was of concern. It should be stressed that the owners of structures over and under roads and railways have an obligation to inspect and maintain these structures in accordance with the procedures set out by the operator of that infrastructure.

Can a robust asset ownership matrix lead to improved safety?

Engineers advising on these structures should ensure that their clients are aware of this obligation. With new structures this is hopefully covered by the Operation and Maintenance (O&M) documentation. There is need for a robust asset ownership matrix, both within separate divisions of one entity, but also where asset ownership may be shared between separate entities. Such a matrix should be shared between asset owners and agreed by all. It is also important that there is adequate quality control of structurally significant change such as alterations and renewals, and of inspections.

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