(The following is one in a series of cases I have investigated that illustrate the different types of structural failures and accidents that occur resulting in civil litigation, and the forensic engineering methods I used to investigate the cause. The series is designed to assist counsel gain an appreciation of the engineering investigative methods used by forensic engineers.
The methods are most important for purposes of this illustrative series. As such, I do not report on the analysis of the evidence uncovered during the investigation)
The investigation is reported under the following main headings with several sub-headings:
- The case (A description of the accident and the scene, also, the client and the legal/technical issues)
- Forensic engineering investigation (Building construction/snow and ice formation)
- Cause (Addresses the legal/technical issues)
- Post mortem (Binoculars were an important investigative tool)
A man was walking along a sidewalk in a city in eastern Canada several years ago when a piece of ice fell from a building hitting him on the head and knocking him out. The man regained consciousness some time later in an ambulance on his way to the hospital. A doctor diagnosed severe head trauma. The man took time off work and was treated for his injuries.
The three storey building had a mansard roof – a roof with two slopes, covering the upper level. The roof had several dormer windows. The building was several decades old. The accident occurred on the sidewalk on the south side of the building below one of the dormers.
The man retained counsel to assist him claim damages associated with his injuries.
I was retained by the counsel in connection with the claim for damages and asked to investigate the accident.
Counsel identified the following issues relevant to a resolution of the dispute by the court:
- The design and construction of a building and its roof in relation to safety issues concerning the accumulation of ice and snow.
- Alterations that could be made to a roof or safety precautions that could be taken to prevent accidents.
Forensic engineering investigation
Following is a list of some of the methods I relied on during my investigation of the accident. The methods and tasks are separated according to the issues identified by counsel:
Building construction/Snow and ice formation
- Review documents in general as provided by counsel
- Study photographs of the building and the scene taken at the time of the accident, particularly those marking the location of the accident and the construction of the roof
- Visually examine the scene and the exterior of the building. Note the formation and location of icicles on the roof
- Examine with binoculars details and features of the roof construction, and the general repair and condition of the roof
- Visually examine the formation and build-up of ice and snow on different buildings in other locations I travelled during the forensic investigation. Reflect on the build-up of ice and snow on the roof of my home in the past
- Research the formation of ice and snow build-up on roofs
- Study victim’s statement of accident noting, in particular, what the victim heard at the time of the accident and the extent of the victim’s injuries
- Study a floor plan of the building
- Read the pleadings
- Research methods of altering the roof at the scene of the accident to prevent the formation of ice and snow on the roof
- Examine products available in building supply stores for altering the roof
- Research safety precautions that could be taken to prevent accidents from falling ice
Building and roof construction, including collecting runoff from the roof, were typical for the city. As such, as an older building, the conditions were present in our climate for ice and snow to form and collect on the south side of the building. Inspection and maintenance of the roof drainage system would be necessary to prevent ice and snow falling on people below.
The roof could be altered by various methods, and the methods maintained, to prevent ice forming and snow accumulating. These methods are sold in building suppy stores. One method would involve lining the roof above the eaves with metal sheeting to prevent ice and snow accumulating.
The area of the sidewalk below could be roped off and signs posted cautioning people of the danger of falling ice.
The claim was resolved by alternate dispute resolution (ADR).
The case did not go to trial.
The extent of the man’s injuries was evidence in giving some indication of the size of the piece of the ice that struck him. I now want to know the extent of a victim’s injuries in all accidents I investigate.
Also, the sound the man heard, suggestive of ice hitting the roof of the addition, corroborated the location of the accident and the area of the roof from which the piece of ice fell. It was easy to explain the formation of ice at this area of the roof.
Examining the roof with binoculars was the only way to assess maintenance of the roof drainage system. Less than adequate maintenance was a factor in my analysis. I wasn’t privy to its importance in resolving the case.