This guidance note focuses on construction design, building standards and site selection, and their role in the mitigation of risk due to natural hazards. The note provides general guidance for design professionals and funding organizations involved in development projects concerning the construction of new infrastructure, strengthening intervention on existing infrastructure and post-disaster reconstruction. It provides guidance for analyzing the potential threat posed by poor construction and inappropriate land use in hazard-prone areas.
Only formal constructions (mainly buildings) are considered and some guidance is given on designing structural intervention (construction or strengthening) plans to help mitigate risk from natural shards to vulnerable people, their livelihoods and the local economy. No specific technical solutions for the latter are proposed as each location and hazard requires a solution tailored to local needs and resources. However, references for further reading on technical issues are provided.
Hazard risk mitigation infrastructure is not covered by this guidance note. 1. Introduction A significant part of development assistance is spent on the construction of infrastructure in developing countries. However, these investments and associated development gains can be lost in seconds in the event Of a natural izard event (see Box 1). The majority of human and direct economic losses from a natural hazard event occur as a direct result of damage to the built environment and/or ineffective early warning and evacuation systems.
The negative impact of natural hazards on communities can be limited by taking such hazards into consideration when selecting sites, designing new infrastructure and strengthening existing infrastructure. The exclusion of hazard mitigation measures in development projects is unacceptable in view of the increasing disaster risk in developing countries caused by environmental degradation (see Guidance Note 7) and growing arbitration, with the accompanying rapid increase of poorly built housing, uncontrolled use of land, overstretched services and high population densities.
Consequently, development organizations should be accountable for the hazard-proofing measures they include in their construction projects, and for the losses resulting from their inclusion. This applies to projects where a hands-on approach is adopted or where the work is carried out by others.
BOX 1 Consequences Of ignoring hazards in construction The following examples show how the lack of hazard measures or reliance on coal best practice only can lead to large human and economic losses and set back development goals in the event of a natural disaster: ; In the years preceding the May 2000 floods, the World Bank financed the construction of 487 schools in Macaque according to local building practice. However, during the floods 500 primary schools and seven secondary schools were damaged or destroyed, 1 severely setting back development goals. World Bank.
Hazards of Nature, Risks to Development: An GIG Evaluation of World Bank Assistance for Natural Disasters. Washington, DC: World Bank, Independent Evaluation Group, 2006. Available at: http://www. Workloads. Org/ gig/underestimates/ Gu i dance No et 12 The Caribbean Development Bank, the Limited States Agency for International Development (SAID) and the government of Dominica funded the construction of a deep-seawater port in Woodbine Bay, Dominica. The Delft Hydraulics Laboratory (Netherlands) carried out a specializes study of the hazards at the port and submitted a report.
The contractors who designed the port ignored the maximum wave height indicated in the report and built the port to withstand waves of less than half that height. In 1979, one year fête the completion of the project, port structures and facilities were severely damaged by Hurricane David. Repair costs amounted to ISIS 3. 9 million (estimated for 1982), 41 per cent of the port’s construction costs. The Caribbean Disaster Mitigation Project (CDMA) determined that strengthening the port structures at the design stage would have cost only 10 per cent of the construction costs. The 2001 Bush earthquake in India led to widespread damage, including the collapse of 461 ,593 rural houses of rubble masonry construction. Good seismic codes of practice exist in India, but their non enforcement, combined with poor inspection procedures, led to the failure and heavy damage of 1 79 high-rise reinforced concrete buildings in Metadata, 230 kilometers away from the epicenter. Damage to port operations and industry resulted in approximately CSS$ 5 billion of direct and indirect losses. Hurricane Mitch, which hit Honduras in 1998, resulted in a loss equivalent to 41 per cent of the country gross domestic product (GAP). 4 Hurricane Luis in 1995 caused losses to Antigen and Barbuda equivalent to 65 per cent of their GAP. 5 In January and February 2001, two major earthquakes devastated II Salvador. More than 1 65,000 homes were destroyed and 1 1 0,000 damaged. In the most affected areas, up to 85 per cent of the houses were destroyed. The degree of destruction can be attributed to two main factors: the building material used and the quality Of construction and maintenance. 2. Current state of the art In past development initiatives involving the construction of infrastructure, the option of designing and building to reduce the vulnerability of infrastructure to natural hazards has often been ignored due to the perceived higher costs and lack of appropriate expertise. Furthermore, the selection of he location for services or critical facilities has often been made on the basis of land cost and availability, rather than from consideration of safety from potential natural hazards.
Typically, development organizations rely on ‘best local practices’ in hiring contractors to undertake construction work. Problems arise when best local practice does not incorporate the use of any building codes for hazard resistance or uses building codes that inadequately account for local hazards. The latter type Of code typically exists in countries where infrequent natural hazards occur or where there is an incomplete satirical record of past natural disasters. This results in hazard or zoning maps that do not adequately represent the frequency of occurrence or potential magnitude of natural hazards (see Guidance Note 2).
Even when appropriate building codes exist, their correct application requires skilled engineers, architects and builders and effective enforcement and inspection procedures. Poor governance and corruption, leading to, for example, abuse of land use controls and building permits and codes, and illegal expansion of buildings, often exacerbate damage caused by disasters. In addition, most evolving countries lack certification and licensing processes for professionals and enforcement procedures are non-existent.
Enforcement procedures have, however, also been found to be ineffective in some developed countries, as was highlighted by Hurricane Andrew (1992) in Florida, ASSAI, and the Commit earthquake (1999) in Turkey. The adoption of best local practice and of opportunity-based land use can, therefore, lead to a promotion of existing weaknesses in buildings and infrastructure. Funding and development organizations alike need to ensure that experienced hazard specialists and engineers coordinate or implement instruction projects (by either employing them directly or ensuring that the contracted work will be led by such people).
This specialist (or team of experts, depending on the number of hazards and scale of the project) should set a framework for the design and construction, which may then be executed by other engineers, builders and workers. 2 3 4 5 6 2 COM. Costs and benefits of hazard mitigation for building and infrastructure development: A case study in small island developing states. Caribbean Disaster Mitigation Project publication series. Washington, DC: Organization of American States, 2004. Available at: http://www. As. Org/CDMA/document/ papers/items. HTML MAE. The Bush Earthquake of 2001. CD Release 01-04.
Mid- America Earthquake Center Reconnaissance Report, 2001. Gunned-Jones, A. Land-use planning: How effective is it in reducing vulnerability to natural hazards? Institute of Civil Deference and Disasters Studies, 2006. Available at: http://www. Acids. Org/ Gibbs, T. How can the resilience of infrastructure be increased? Proceedings of the 82nd Hilton Park Conference, Weston House, West Sussex, England, 9-1 1 September 2002. Dowling, D. M. ‘Adobe housing in El Salvador: Earthquake performance and seismic improvement. In Rose, W. I. Et al. (des), GSA Special Paper 375: Natural Hazards in El Salvador.
Geological Society of America, 2004, up 281 -301 Oversimplification’s-Disenfranchisement’s s aster Risk Reduction Contrary to common perception, the implementation of hazard-proof measures in building can be relatively inexpensive in terms of construction costs. What can be expensive is the provision of an effective framework for the take-up of these measures (e. G. , the provision of skills training appropriate hazard studies, research into low-cost strengthening solutions). However, if an effective mechanism exists for the enforcement of quality control and codes of practice, these costs will all be covered by the construction industry.
The problem in many cases is the lack of legal mandating of building codes and consequent lack of their enforcement, which puts the onus on agencies commissioning and funding development projects also to provide the necessary research and development, training and education. However, CDMA found that the development and enforcement Of appropriate building codes and standards do not make development costs prohibitive. An investment in disaster mitigation can result in a manifold saving in disaster relief and development setbacks (see Box 2).
Where development agencies have invested in the promotion of hazard-resistant construction, many of the projects have been well thought out and have shown large benefit (see Box 3). Box 2 What is the cost? The implementation of hazard-proof measures in building can be relatively inexpensive and provide longtime benefit to development projects: ; The implementation of simple modifications to improve the cyclone-resistance of (non-masonry) catch or temporary houses in Bangladesh is only 5 per cent f the construction costs. ; Introducing earthquake-resistance principles (optimum layout, use of capacity design principles and more stringent criteria for the design of connections) in the design stage of modern infrastructure will increase the construction costs by 5 to 14 per cent. ; The retrofit for hurricane resistance of the Victoria Hospital (SST Lucia) in 1993 and the Princess Margaret Hospital (Dominica) in 1980 was estimated by Consulting Engineers Partnership to be, respectively, 1 per cent and 2. 2 per cent of their contemporary replacement costs. 9 3.
Merging hazard-risk considerations in construction rejects An integrated and comprehensive approach is necessary to improve the safety of buildings from natural hazards. This includes investing in strengthening existing structures and promoting safer building in development projects and post-disaster reconstruction projects. In hazard- prone countries, it is essential that both funding and development organizations ensure that engineers specializes in hazard-resistant construction be consulted in the initial stages of construction projects.
BOX 3 Some observed successes Ascertaining whether the use of safe building or strengthening techniques successfully provides adequate hazard resistance is not easy, as the constructions have not been subjected to the hazard they were designed for. Some exceptions do, however, exist: ; In 1977, following a cyclone that devastated coastal areas Of Andorra Pradesh, India, a voluntary group, AWARE, built 1 ,500 houses in Krishna District. These houses followed the Central Building Research Institute’s cyclone-proof designs, which consisted of concrete block (made of cement and granite rubble) walls with a reinforced concrete slab roof.
Of these houses, 1,474 withstood the stronger cyclone that hit the region in 1990. 10 7 COM (2001 Lewis, J. And Chisholm, M. P. ‘Cyclone-resistant Domestic Construction in Bangladesh’. In Hodgkin, R. L. P. , Sera, S. M. , and Chuddar, J. R. (des), Implementing hazard-resistant housing. Proceedings of the First International Housing and Hazards Workshop to Explore Practical Building for Safety Solutions, Dacha, Bangladesh, 3-?5 December 1996. 9 Gibbs (2002); see footnote 5. 10 Sir, AIMS. And Reedy, IA S. ‘The cyclone-prone coastal region of the State of Andorra Pradesh, India – A state-government approach’.
In Susan, Y. Et al. , Developing building for safety programmer: Guidelines for organizing safe alluding improvement programmer in disaster-prone areas. London: Intermediate Technology Publications, 1995. In Peru, sheets of welded steel mesh covered in cement-?sand mortar were applied to the walls of existing adobe houses during a prototype strengthening programmer. When the Reequip earthquake shook Peru in 2001, these houses survived undamaged, while nearby houses collapsed or were severely damaged. Al Only two schools were left standing in Grenade after the passage of Hurricane Ivan (September 2004).
Both had been subject to retrofit through a World Bank initiative. One of the schools was used to souse displaced persons after the event. 12 After the passage of Typhoon Asians in the Philippines in 1987, the Department of Social Welfare and Development, in consultation with the Asian Disaster Preparedness Center (ADAPT), constructed 450 housing units. They were designed with a core shelter consisting of concrete footings with steel post straps bolted onto four wooden corner posts and frames, roof frames and trusses. Indigenous materials were used for all roof and wall cladding.
The houses resisted two subsequent typhoons without significant damage. 13 Between 27 August and 18 September 1 995, Hurricanes Luis and Marilyn caused damage to 876 housing units in Dominica causing a total loss of LIST$ 4. 2 million. The small wooden houses that were destroyed did not comply with local building codes. But all the buildings that had been retrofitted, which consisted of simple modifications to local construction, through the CDMA Safer Construction Programmer successfully withstood the hurricanes. 14 On 29 May 1 990, an earthquake of magnitude 5. Struck the Alto-Mayo in north-eastern Peru. The poor standard of construction (mainly houses made of typical or rammed earth) resulted in the loss of over 3,000 houses; 65 people were killed and 607 injured. Technological Intermediate (IT Peru)1 5 introduced an improved quinces house, which slightly modified traditional technology in order to reduce vulnerability to future earthquakes. When a second earthquake of magnitude 6. 2 hit the region in April 1 991, 70 quinces houses had been built and local people could see for themselves that they were more hazard resistant.
A further 1, 120 quince’s were built with aid from IT Peru over the next five years and later, local people built another 4,000 similar houses. In order to set the design criteria for a risk reduction project, the hazards, the rent risk and level of risk that is socially acceptable must be identified. A multi-hazard appraisal should be carried out at an early stage to identify the types of hazards, their likely severity and recurrence (see Guidance Notes 2 and 7). An evaluation of the current risk includes identifying locations most likely to become unsafe in the event of a natural hazard (e. . , areas prone to flooding. Landslides or earthquake-induced liquefaction) and assessing their land use, as well as assessing the ability of local construction to resist the identified hazards. A survey of existing buildings and infrastructure can identify significant vulnerabilities prior to the occurrence of a hazardous event. In a post-disaster scenario, lessons can be learned from the behavior of different construction types during the event. Post-disaster diagnostic surveys should be integrated into disaster reconstruction programmer.
In order to determine the socially acceptable risk, 16 local and national building codes, 17 international legislation and good practice should be examined to obtain an idea of current accepted levels of risk for different hazards and infrastructure. For example, in the case of most earthquake engineering odes, Structures of normal importance are designed to withstand an earthquake with a 10 per cent probability of being exceeded in 50 years (i. E. , an event with a return period of 475 years). The local government and community should then be consulted and a level of risk determined for the design.
It is important to note that the level of socially acceptable risk will vary according to the use and importance of the facility and the desired post- natural hazard event performance. Finally if, for the identified hazards, the level of current risk is greater than that which is socially acceptable, then the deed for hazard-proofing (and/or re-sitting) is established, and the socially acceptable risk and identified hazards become the design criteria for the new construction or strengthening works. 11 Blonder, Garcia and Breeze (2003). 12 World Bank. Grenade, Hurricane Ivan: Preliminary’ Assessment of Damages, September 17, 2004.
Washington, DC: World Bank, 2004. Available at: http://stereoscopes. Workloads. Org/ANTISMOG/Resources/ grenade_assessment. PDF 13 Deacon, D. ‘Typhoon resistant housing in the Philippines: The core Shelter project’. Disasters, 16 1992. 14 COM. Toolkit: A Manual for Implementation of the Hurricane-resistant Home Improvement Program in the Caribbean. Caribbean Disaster Mitigation Project publication series. Washington, DC: Organization of American States, 1999. Available at: http://womb. As. Org/CDMA/document/toolkit/toolkit. HTML 15 Based on Maskers, A. ‘The Alto-Mayo reconstruction plan, Peru -? an MONGO approach’.
In Susan et al. (1995) and in Ferreira, P. , ‘Post-disaster housing reconstruction for sustainable risk reduction in Peru’, Open House International, 2006, 31(1 16 Socially acceptable risk is the probability of failure (damage) of infrastructure that is acceptable to governments and the mineral population in view of the frequency and size of natural hazards, and the infrastructure use, importance and potential consequences of its damage. For example, it is unacceptable that a nuclear power station be damaged by any natural hazard event; the acceptable risk is, therefore, zero.
In most cases constructing buildings and infrastructure that can fully resist the largest possible natural hazard is uneconomical (and often unjustified due to the rare nature of some natural hazards). Hence a limited risk is accepted. 17 Building codes are defined as standards and guidelines for the construction of alluding and infrastructure to a minimum level of safety for the occupants. See COM, Hazard-resistant Construction. Washington, DC: Organization of American States and Squid’s Unit of Sustainable Development and Environment, 2006. Available at: http://www. As. Org/CDMA/gabbled. HTML OVERCOMPENSATION’S Box 4 -Tools for Mainstreaming D Challenges, opportunities and good practice in post-disaster reconstruction Post-disaster reconstruction projects present a real opportunity for the introduction of hazard-proof measures in construction and land use planning. Heightened hazard awareness and increased funding for construction can be rareness to promote these measures and to achieve the legislative reforms required for regulating land use, hazard-resistant building code change, enforcement and construction quality control.
Development and humanitarian agencies should take a coordinated approach to reconstruction in a post-disaster scenario. Furthermore, local or national governing bodies must support major reconstruction initiatives. It is important that viable institutional frameworks and appropriate funding partnerships are established. Reconstruction should not be precipitate. Immediate needs can be addressed with temporary measures and a realistic timescale should be established which will allow hazard-proof design experts to be consulted and long-term goals to be considered in the reconstruction.
Social needs, land availability and economic constraints mean that it is not always possible to secure land that is safe from all hazards in post-disaster reconstruction. However, it is still possible to reduce future losses from disasters through appropriate construction and planning measures. It is important to note that resources made available immediately after a disaster for reconstruction will probably not be available for longer-term opacity building or to bring about a change in practice.
One solution, contained in the United Kingdom’s Department for International Development (DAD) Disaster Risk Reduction policy paper, 1 8 is to set aside 10 per cent of disaster funds to reduce the impact of related future disasters. Throughout the project design and implementation it is essential that local stakeholders are actively involved. Local stakeholders include the direct beneficiaries, the wider affected community, local authorities, government and local academic and building experts.
This will aid in the development of a rule sustainable technical solution (for infrastructure strengthening or reconstruction) and will increase acceptance of the project. A sustainable and successful project goes beyond site selection, the choice of a sustainable solution and training of local builders, to also involve issues of land tenure, finance, education for risk awareness and future maintenance (see Box 5). Box 5 Beyond building Proposing safe building or repair and strengthening practices is not sufficient to ensure take-up by communities.
Integrated, community-based approaches for safer building should be promoted by: ; raising hazard awareness wrought education; ; community participation in developing the project, in decision-making and in design selection; ; developing locally acceptable, affordable and sustainable technological improvements; ; developing effective ways of communicating technical messages to target groups; ; skills development training for local builders and craftspeople; ; improvement of general living conditions; ; training architects and engineers (in both public and private sectors), building officials and building by-law enforcement officers; and ; community-based disaster preparedness planning. 19 Hospitals are critical facilities for post-disaster relief, and it is not only the loss of structural integrity that can compromise operation but also damage to hospital equipment and to surrounding infrastructure (e. G. , loss of access, water supply and electricity). Full structural, contents and systems network risk analyses should be carried out. The pan American Health Organization (PAPA)20 provides a series of guidelines for such analyses. Apart from the enormous emotional impact of student deaths, damage to schools and the loss of teachers have a negative impact on the education of survivors. Schools