Posted in Issue 110 - October 2008 New Tools
There is a underlying need for information on the hazard of winds based on meteorological records and methodologies recognized by the scientific community. Precisely to fulfil this need, PAHO/WHO together with Applied Research Associates, an institute in the United States, and experts from the Caribbean created new wind hazard maps, a tool which shows the hazards of winds in the Caribbean islands, the Caribbean coasts of Central America, South America and the Yucatán Peninsula, a wider area than that covered in existing maps.
“Every day engineers in the Caribbean design projects which must be wind-resistant. …Clients wish to specify the levels of safety of their facilities, insurance brokers wish to know the risks they are taking on and financial institutions wish to include criteria regarding wind in their schemes”. Many of these decisions depend on the quality of information available regarding hazards, states Mr. Tony Gibbs, regional coordinator of the project through which the new wind hazard maps were created.
The maps, updated with information collected over the last 20 years and the most advanced meteorological methods, will replace those used since 1985 in the structural design of buildings and risk assessment. These simulate 100,000 years of cyclonic activity.
Harmonization of norms
The information which can be taken from the wind hazard maps arrives at a time when the region is preparing to draw up new construction norms. Countries can include this in their technical norms or regulations and in this way will have more effective procedures to control the design of health facilities.
Currently, new regional standards are being put forward in a Caribbean Development Bank project which is carried out by the Regional Caribbean Organization for Standards and Quality. The result will replace the construction code in force at the moment.
The wind hazard maps complement this project well since they were prepared taking into account international norms and provide information on the behaviour of winds, an aspect which had not been considered in the project.
Although some of the countries taken into account did not have wind maps, the same methodology was used for all of them, which implies unified criteria for design and safety levels when these technical standards are applied.
The period of time under consideration for the development of the new maps is equivalent to the existing history of tropical cyclones (storms and hurricanes) in the North Atlantic, including the Caribbean. Studies for the creation of the maps were based on historical records of storms and hurricanes which took place in the middle of the 19th century; nevertheless, greater emphasis was placed on the period between 1970 and 2007.
“Recent history is more reliable, as a result of which more emphasis was placed on this in the study. Even so, this information is insufficient to carry out statistical analyses and appropriate forecasts”, explains Gibbs. The study showed that there have not been significant changes in the cycles of cyclonic activity in the North Atlantic.
But the results are tremendously useful. With these, countries can adopt more effective procedures for monitoring standards in the design of health facilities with the aim of making them more resistant to winds and hurricanes. In addition, the information can be used to carry out vulnerability analysis of existing buildings or to take corrective actions. To date, the health sector had depended on the opinion of its advisors (engineers and architects) and the use of technical standards.
Although the maps are new (February 2008) and known to a “minority” of consultants, a programme for dissemination and promotion of these has been started. The results of the studies were presented in international and regional meetings in Trinidad and Tobago, Belize, Saint Lucia and the Virgin Islands and it is planned to present them in the Bahamas in September and in Saint Maarten in December.
Courses, seminars, conferences and dissemination through internet are some of the channels to be used in the process of spreading information on these manuals.
“Responsibility for the promotion and use of the information must be shared by all interest groups (administrators from the health sector, donors, financial bodies, engineers, architects, the insurance industry). Certainly, engineering professionals will seek to play a crucial role”, states Mr. Gibbs who is providing information on the tool in different fora.
PAHO/WHO promotes the use of (check consultants) with technical knowledge to carry out assessments of design and quality in the different stages of the projects and they will ensure that information from the maps is used appropriately in the construction of new health facilities.
The wind maps project was financed by the Office of Foreign Disaster Assistance of the United States Agency for International Development (OFDA/USAID).
* We should like to thank Mr. Tony Gibbs for the information provided for this article.