Bermuda Offers Lesson In Hurricane Preparedness

Immediately following the storm, AIR dispatched a post-disaster reconnaissance team to inspect the damage and further assess the impact of wind and storm surge on structures.

Data gathered from post-disaster site surveys are critical to the development and subsequent validation of catastrophe models. Through such inspections and analyses of the data collected in the aftermath of actual storms, catastrophe modelers can validate the damage functions used by their models in light of new building codes, construction practices and building materials in order to provide the insurance industry with the most reliable loss estimates possible.

Lessons learned from Fabian, in particular, confirm our understanding of damage patterns to buildings of stone or reinforced concrete.

Damage to the 21-square-mile island was widespread, but varied considerably depending on location. The southern part of the island took the brunt of Fabian and possibly acted as a buffer that shielded Hamilton, the capital and home to numerous insurers and reinsurers, from the most severe winds. The southwestern part of the island suffered no significant wind damage to structures. Small pockets of damage to buildings were observed in the northeastern part of the island with widespread damage to roofs. There was some evidence of the effects of the islands topography on winds, with more damage to properties situated on the windward slopes and less damage to properties in valleys and on the leeward side.

The sturdy stone and concrete construction evident in Bermuda is unique compared to many islands of the Caribbean and to the mainland United States. Building codes are quite stringent and evidence suggests that enforcement is quite good. Building designs in Bermuda must conform to the British Code, requiring that they be built to withstand sustained wind speeds of 110 mph. In addition to the excellent wind resistance of such buildings, good construction quality, code compliance and general hurricane preparedness helps reduce the hurricane vulnerability of buildings in Bermuda. It is likely that a storm of similar intensity would cause significantly higher insured loss were it to hit similarly populated area in the mainland United States.

Many homes on the island are traditionally constructed of the so-called "Bermuda Stone"–a locally quarried limestone–with some modern structures built of concrete blocks. Roofs are constructed using 18 inch-by-12 inch, one-inch thick, quarried limestone slates laid directly and cemented together, in an overlapping pattern, onto timber rafters. The pastel-colored houses, for which Bermuda is famous, with their lime-washed, "stepped" roofs, give the building stock in Bermuda a soft and serene feel. But these houses are also extremely strong and well built, and are capable of withstanding a severe hurricane reasonably well.

Most residential structures are of one or two stories. Commercial buildings typically do not exceed six stories and are normally constructed of reinforced concrete. There are few industrial buildings. Window openings are generally small and the use of Bahama and Colonial shutters–common in both residential and commercial buildings–increases wind resistance.

In assessing the damage from Fabian, residential buildings faired better than commercial properties in most cases. Most of the damage to private residences was limited to roofs, which in many cases lost corner slate. There were few cases of complete roof failure. Damage to windows was largely absent due to the small size of windows and the use of storm shutters throughout the island.

Commercial properties took a larger hit with about three-fourths of the islands hotels and guesthouses suffering some degree of damage. There was extensive damage to the Ariel Sands, Fairmont Southampton, Pink Beach Club and the Sonesta Beach Resort. All of these properties had significant wind damage to their roofs. Since most are situated on the beachfront, storm surge as high as 24 feet was also a big contributor to losses.

Although Fabian was an intense hurricane, the relatively moderate levels of damage and disruption suffered by Bermuda demonstrates the benefits of effective building codes and good construction practice. On the whole, the type of damage sustained by structures on the island underscores the hurricane preparedness of the population and should serve as a lesson in hurricane disaster mitigation.

Atul Khanduri is manager of wind engineering at AIR Worldwide, a Boston-based catastrophe and weather risk modeling subsidiary of Insurance Services Office in Jersey City, N.J. Mr. Khanduri was the leader of AIR's post-disaster reconnaissance team sent to Bermuda after Hurricane Fabian.

Reproduced from National Underwriter Property & Casualty/Risk & Benefits Management Edition, September 19, 2003. Copyright 2003 by The National Underwriter Company in the serial publication. All rights reserved.Copyright in this article as an independent work may be held by the author.