The construction industry is fraught with dangers that might develop from the various activities that take place on and around building sites. Construction workers engage in a variety of activities that can expose them and others on the job site to serious hazards such as unguarded machinery, falling from rooftops, electrocution, silica dust, being struck by falling objects or heavy construction equipment, and the effects of noise pollution (Hughes & Ferrett, 2012). The health and safety requirements ensure that all workplaces are safe, and that everyone on the site or nearby is safe. The health and safety regulations impose duties and responsibilities on the client, the principal designer, the designer, principal contractor, contractor and the workers. Precautions to ensure safety include:
Ample Access and Egress
Workers must be able to access or get out of their workstations without being exposed to dangers of falling, being hit by objects or machines.
Precautions against Falling Objects
The site must be fenced to avoid unnecessary access; support props must be erected on the elevated walls under construction to avoid fall or collapse (Hughes & Ferrett, 2012). There should be a fence of safety nets around the walls under construction to prevent stray falling objects. Besides, the safety walls around the site are important in guarding the operation areas where objects are likely to fall. Adequate warning signs are important in keeping people away from the unsafe areas.
Proper Housekeeping
Right housekeeping must be maintained by ensuring material and operation equipment are kept in safe storage, scraps and debris must be disposed at safe sites (Hughes & Ferrett, 2012). Loose materials not in use must be kept in store. Proper labeling of materials is important more so for chemical products that may have explosive reactions.
Personal Protective Equipment and Clothing
Workers must be provided with equipment and protective wears to safeguard them against injury to health and accidents (Goetsch, 2013). Examples of safety wear include boots, helmets, safety jackets hand gloves or gauntlets, life preservers and protective eyeglasses (colored goggles). Protective equipment includes face shields, self-contained breathing apparatus, and tight-fighting boiler suits. In addition, the supervisors at the site must have strict laws on having the protective clothing before accessing the construction site.
Adequate lighting
There must be adequate lighting at all points in the construction site from stores, to access corridors and in the workstations to avoid accidents (Goetsch, 2013). The supervisors must provide artificial lighting like lamps in areas where there is no adequate natural lighting. In cases of overnight operations, there must be adequate sources of lighting.
Scaffolds and Ladders
The scaffolds and ladders used must be of standard quality in terms of material used and the design (Goetsch, 2013). The setting of the scaffolds and ladders on the site should be on stable grounds and with safe means of access and egress like stairs or ramps. In addition, routine inspection and supervision are recommended for the scaffolds and ladders to ensure they are always in good shape.
Lifting Machines
The lifting machines used in any project must be selected according to the nature of the load, the maximum safe working load and the safe working load at different radii (Goetsch, 2013). The selected machine is then installed, tested and maintained to ensure the machine is in good condition to avoid failure during operations. The operation of the machines must be by a competent person, in terms of training, health condition and state of mind, at all times.
Transportation, Material Handling, and Earthy Moving
Trucks, earth movers, cranes and other material handling equipment must always be of good design, be in good working condition, be properly used and for the right task and be operated by workers with adequate training, experience, good health and at the right state of mind (Goetsch, 2013). During the operation of these machines, there should be adequate warning signs and protection of the area of operation to avoid collisions and accidents.
Plant Machinery and Hand Tools
This category of construction appliances includes both the manual and automatic tools used at the various workstations (Goetsch, 2013). These tools must be of good design and manufacture, be in good working condition and be placed on the right use. Operators must be provided with safety gears and protective guards. Besides, the right persons with adequate training while in the right state of mind are the ones who should operate the machines and hand tools.
Operations at Heights
Working at heights has risks of tumbles, falling tools or the building materials. Safety during such operations is important to protect the workers and the people around the site. There are standard specifications for operations at various heights that must be adhered to for compliance (Goetsch, 2013). Guardrails and toe boards must be provided for the workers working at heights; if such are not available or impractical, then other safety measures, as safety nets must be in place. The elevated working areas must be provided with safe means of access and way out (Goetsch, 2013). There must be safety nets to trap falling objects. Moreover, during operations at heights, the area must be properly fenced to avoid having people in close proximity that may risk being hit by falling objects.
Reporting of Accidents and Emergency Response
Workers should be given adequate training on the need to report any accidents for immediate actions. Common accidents include falling, hit by falling tools or materials or moving machines, explosions or collapse of walls. Besides, the project managers must have special units at the construction sites that respond to accidents once reported; the respondents include first aid team, fire extinguishers, and rescue team.
Explosives
Explosives are often used during excavations, tunnel drilling or stone crushing. Explosives can be disastrous either directly or indirectly (Törner & Pousette, 2009). An example of the direct effect is an employee getting into contact with the explosives without safety wears while indirect effect includes instances like flying stones hitting people during the explosion. Safety measures while using explosives include having the competent people doing it, those handling them having the right wear, proper location of the explosion site and giving adequate warning and ground survey before the explosion.
Demolition, Excavations, Drilling and Earthworks
These processes may cause ground instability, and so safety standards must be upheld to ensure safety (Törner & Pousette, 2009). Some of the safety standards include having the right machinery, having competent persons in ground operations, adequate information, and warning, an adequate survey of the surrounding and having ground protectors in case of underground operations to avoid walls collapsing on the workers.
Operating over Water
Working over water requires protection from drowning in case one falls in water and protection from reptiles and other dangerous water animals (Törner & Pousette, 2009). Some of the safety measures include having lifesavers on standby, life jackets, manned boats and rescue teams on standby.
Environmental Effects
Construction activities of commercial properties, residential buildings, roads pavements, water dams and retaining walls amongst other have significant impacts on the environment. The impacts of construction activities on the environment can be divided into direct and indirect impacts (Osborn, 2012). Direct impacts include aspect relating to energy, materials and land use, emissions of greenhouse gasses, the release of wastes into the environment and pollution. Indirect impacts include aspects related to the ecological friendliness of the process and effects of occupants of users of the resultant structures. The major environmental impacts of construction activities are as discussed below.
Air Pollution/ effects on air quality
Construction processes are the main emitters of dust, smoke, and odor into the environment. The excavations, explosions, material mixing and moving trucks on dusty roads create huge dust that finds their way into the atmosphere (Osborn, 2012). Chemicals used in explosions and the fuel used to run the machines and trucks are the potential causes of smoke and odor polluting the air.
Greenhouse Gas Emissions
Activities during construction projects like the moving trucks and operating machines have effects on global climate change through emission of greenhouse gasses like carbon IV oxide (Osborn, 2012). Even though the construction process itself induce little greenhouse gas emissions, the resultant use of the constructed structures like roads, railways, factories and buildings which are energy-intensive induces a lot of emissions.
Effects of Land and Materials Use
The use of land and materials in construction has a direct impact on the environment. The extent of impact depends on the type and amount of materials used. The harvesting of materials for use in construction works like soils from borrow pits for use in foundations or road projects can cause adverse impacts on the biodiversity and degeneration of the ecosystem (Balaban, 2012). The quarry extractions destroy habitat for animals and may cause species extinction. Material harvesting may cause unstable or bare grounds that are susceptible to soil erosion causing massive effects on the ecosystem.
Construction materials like timber necessitate deforestation that has resultant effects on catchment areas and leaving bare grounds susceptible to soil erosion. There are indirect effects of land and material use, for example, deforestation to create space for housing projects or roads may have resultant effects like soil erosion and depleted catchment areas reducing the amount of rainfall. The materials used in the road construction like tar, oil, or lime may have negative environmental effects. Having construction sites in areas close to wildlife habitats for the instant construction of railway lines through game reserves may scare away the wild animals.
Effects of Poor Waste Management
There are large amounts of waste released into the environment during construction, and such waste may cause negative effects on the environment. Construction wastes are in groups like concrete-based, soil-based, wood, textiles, and plastics (Balaban, 2012). Some of the common wastes are chemicals like paints, lime, cement, oil and tar that are washed downstream by stormwater to water bodies, an excess of these chemicals have pollution effects on the environment. Poor disposal of plastic bags, excess steel or iron sheets poses serious dangers to people working within site and people living around the construction site.
Noise Pollution
Construction activities like explosions, operating earthmovers, the load trucks, lifting machines and other operations at the sites cause noise impacts in the neighborhoods (Lee, Mahendra & Alvarez, 2010). The noise affects people living around the construction sites and those working within site.
Energy consumption
Construction process affects the environment through its depletion of non-renewable energy used in the process (Balaban, 2012). Examples of non-renewable energy used in construction are fossil fuels including organic matter, the use of crude oil, natural gas, and coal.
Remedies in Construction and Sustainability
The remedies in construction and sustainability are innovative ways of limiting environment effects of the construction process and the resultant use of the structures. Some of the action aimed at realizing sustainable construction include the efficient use of energy, water other resources, protection of the occupants and employees, green housing, reduce waste, pollution, and harm to the environment.
Green Construction
Green construction is a collective term for the construction of houses that limit the environmental pollution and the use of environmentally friendly materials. Green structures are designed to limit greenhouse gas emissions by making maximum use of natural renewable energy, for example, having the architectural designs that allow for maximum use of natural light during the day (Harris & McCaffer, 2013). The green buildings use solar panels in energy provision for lighting at night and for running house appliances. Other features are solar water heaters, solar room warmers, and adequate ventilations to avoid the use of air conditioners.
Housing Tapping Natural Lighting
Renewable Energy Sources
There are three forms of renewable energy including solar, wind and geothermal energy. The renewable energy sources are important in reducing Carbon IV Oxide emissions into the atmosphere by eliminating the use of fossil fuels or crude oils. Renewable energies can be used in powering home and office appliances, home lighting, and street lighting and for powering construction machines.
Solar panels On Residential Houses
Use of natural resources
New systems in construction are limiting the use of raw materials that have negative effects on the environment. Examples of natural resources include the use of laterite soils, ash and quarry dust in the stabilization of clay soils to reduce the use of chemical stabilizers. Other examples include organic paints, the use of unburnt bricks, and the use of natural renewable energies.
Reducing Construction Wastages
Sustainable construction defines proper material estimation and proper use of construction materials to avoid wastages. Examples of waste reduction include recycling materials, re-use and putting material off-cuts into other use.
Use of Locally Available Resources
Making use of materials available locally like having borrow pits next to construction sites is important in reducing the cost of transportation through cutting down on the energy consumption by the transporting trucks. The reduced distance traveled while transporting the materials also reduces the amount of emission by the trucks.
Waste Management
Sustainable construction has recommendations for proper waste management through recycling and reuses or proper disposal of non-renewable wastes (Lützkendorf, Hajek, Lupíšek, Immendörfer, Nibel & Häkkinen, 2012). Concrete wastes after demolition can be used in filling foundations, plastic bags containing materials like cement can be recycled, and other materials like timber of steel off-cuts can be put into other use.
Sustainable Water Management
Clean water is increasingly being a concern in most parts of the world that necessitate joint action by all industries. Sustainable construction recommends the minimal water use during construction. Minimizing water use can be by using mixers in concrete process unlike mixing concrete on the ground that loses water through seepage (Crabtree & Hes, 2009). The curing process can be by curing bags unlike the use spraying water on the concrete surfaces. Water for use in construction process can be from rain harvest or recycled water from household wastes to avoid the use of clean water supplies. In addition, the wastes and toxic substances from the construction sites must not be disposed of water bodies.
Design and Build Procurement Route
Design and build procurement route defines the process in which the main contractor is appointed to take charge of the design and construction works as opposed to the traditional system where the client appoints a consultant to design the proposed structure and a contractor is appointed to do the construction work (Koranda, Chong, Kim, Chou, & Kim, 2012). The design and build system is often recommended for small scale projects that do not require detailed design and supervision. Design and build have its advantages and disadvantages.
Advantages
Construction process starts earlier hence reducing the overall time spent to deliver the project. The client has only one organization to deal with from in the whole project from start to completion (Aziz & Hafez, 2013) This system is more flexible since there is only one organization thus the client can change the design at different stages of the project. Since there is only one organization involved, the overall costs to the client are reduced.
Disadvantages
Giving the design and construction to a single organization may jeopardize quality sine the contractor can manipulate the design for his/her advantage. The quality structure may be compromised since there is no oversight organization to ensure all the standards are maintained.
Modern Methods of Construction
Modern Methods of Construction (MMC) involves creativity and technology to solve previous challenges in construction that were characterized by wastage of time and resources. Currently, Construction industries can apply MMC to design materials to construct both vast and medium sized structures. In addition to reducing time and cost of building, MMC focus on reducing waste, pollution, and risk to engineers in the construction site. To save time and reduce risks that are prevalent during constructions, MMC categorizes building material regarding material and place of regarding places location where they are built as far as their need is concerned during the building process. Following vast building techniques, a variety of materials and current trends in construction, The Housing Corporation employ five broad categories to define Modern Methods of Construction.
Off-site manufactured - volumetric
Off-site manufacture happens under factory-controlled conditions where engineers engage in building 3D volumetric structures that are later relocated to the site of construction in different forms. Building components commonly designed off-site include complete 3D structures that fully fitted and external finishers that are in parts ready to be joint to various parts of an existing structure (NHBC Foundation (2016). The finished are transported to the construction site depending on their material and size to prevent damage or weakening. The off-site manufacture has improved MMC tremendously because it enables designers to maximize their accuracy and creativity when designing construction components away from disruptions in the site. Embracement of an off-site method of construction has reduced accidents that are prevalent in during building by decongesting the site.
Off-site manufactured - Panelized Systems
Off-site Manufacture is a Modern Type Method of Construction that involves creating flat panel structures such as wall units and floor finishers within the factory before being transported to the construction site to fit and complete existing 3D structures. The panelized system of construction also involves designing building components such as wall finishes, windows, and doors to be enjoined into a building. Panelized system surpasses traditional construction because it facilitates repetitive production of construction materials to achieve uniformity. The panelized system is handy in construction because it allows usage of both timber and light steel that are easy to handle and transport to the site. Construction companies that have to embrace an off-site panelized system of development have benefited by achieving creativity and uniformity in their products depending on their respective uses. Also known as cross-wall construction, the panelized system enables constructors to save time by producing using similar technology to produce multiple structures that are fitted to readily available 3D structures.
Off-site Subassemblies and Components
Subassemblies and components is a current type of construction that involves incorporating massive building structures into buildings. Sub-assembly structures include construction of large block panels using concrete and fitting them together to an existing building. The building method further includes enlarged polyethylene panels that are installed to walls of already constructed houses to provide thermal insulation and prevent excessive sound external sources. Sub-assembly components are further used to build roofs and floors of buildings and are essential in large construction processes such as building a hotels and student residential.
Off-site manufactured - hybrid
Hybrid concrete production is current method of construction that that combines both panelized systems of development and 3D dimension construction to produce volumetric units that can be integrated existing buildings (NHBC Foundation 2016). The combination of more than two construction processes enables constructors to achieve quality because the structures are developed together. Additionally, the hybrid development process is advantageous to builders because it allows them to achieve efficiency and quality due to the repetitiveness of the process. The inclusion of both panelized and 3D modern construction is convenient for construction because it is cost effective and minimizes waste.
Non-off-site manufactured MMC
Also known as site-based MMC, non-off-site construction involves making thin joint block works that are fitted to various positions in a building that fit their design. The site-based construction technique is majorly used to do finishing to different parts of the building that need adjustments. The method of building is significant in construction because it allows engineers to employ creativity to solve mistakes that arise during construction as result of inaccuracy in measurement (NHBC Foundation (2016). Further, site-based construction is convenient in construction because it enables a construction team to remedy problems that arise due to ignorance of certain procedures during building.
Sheet Pilling as Retaining Wall
Sheet piles are piles that are molded from sheet metals, wood or vinyl in interlocking format with other piles to form retaining wall. The piles are driven into the ground side by side to form vertical wall for retaining soil. Horizontal Wallers, tiebacks and braces are often used with the sheet piles to provide alignment and resistance or thrust (Inui, Chau, Soga, Nicolson & O'Riordan, 2011). The choice of pile to use in a project depends on the ground, availability of material, ease of installation, the ability to withstand driving, the latera strengths and the ease of making connections. The types of sheets are relative to the materials used. Some of the common types include:
Wooden sheet pile
This type of piles is made in various sizes and forms. The nature of the site for which the piles are to be used determines the choice of the type of wooden pile.
Pre-stressed concrete sheet piles
This is the commonly used sheet pile for retaining walls. The piles are reinforced from all the faces so that the piles can be handle from either side. The pre-stressed sheet piles are relatively lighter in weight, more durable and economical when the costs are compared in the long run (Bilgin, 2010). These piles can be used in seawater since they have negligible risk of cracking, plus the pre-stressed concrete piles are corrosion resistant.
Precast concrete Sheet Piles
The term precast refers to the process of molding the piles offsite and delivering the ready piles for installation. Precast sheet piles can have square or rectangular cross-section.
Steel sheet pile
This type of sheet pile is made of rolled steel sections. The design consists a plate often referred to as the web provided with integral interlocks. The interlocks consist of groove. There are three main types of steel sheet piles: straight-web type, Z-web type and shallow or deep arched-web type (Bourne-Webb, Potts, König & Rowbottom, 2011). Steel sheet piles have several advantages over the other types like the advantage of being lighter in weight, ability to be reused in different projects and longer service life.
Site Set-Up, Accommodation, Store and Security
Construction site setting has several requirements to ensure safety and convenience to the workers. Site setting describes the process of having all the necessary requirements on the site before the construction process begins. Every construction site must have a site office, a store, washrooms, first aid room/health room and or kitchen. The site must be fenced to keep away unauthorized access. Every construction site must have site office where the drawing and designs are kept and interpreted before implementation. The site office also provides space for consultations.
Accommodation is not mandatory for all projects but depends on the location of the site, accessibility and the number of hours the construction process is set to last each day. In sites located in remote areas accommodation is compulsory since workers cannot get accommodation from within the neighborhood. Projects located areas not easily accessible also mandate compulsory accommodation for all workers. In projects that are required within a shorter time that then demands to extend working hours require workers to stay close to the site n so necessitate accommodation.
Storage is important in all construction sites to help in keeping safe the machines, construction equipment, and materials that are not in use. Proper storage is also the art of safety measure since workers are not exposed to equipment that may cause injuries. Security is important in keeping the construction site out of reach of unauthorized persons. Keeping people ways helps on reducing cases of materials and equipment theft and a safety measure for the outsiders not to be exposed to hazards from the site.
Excavation and Ground Water Control
The main challenge during excavations is ground water control. Ground water control describes the process of reducing groundwater levels to allow for ease of operations. There are several mechanisms that can be employed to help in ground water control.
WellPoint Systems
This process is used in lowering the groundwater levels and in the provision of safe working conditions during the excavation process (Bear, 2012). The WellPoint system comprises several small diameter wells that are connected to a header pipe to a WellPoint pump. The WellPoint pump is placed in the system to create a vacuum that then draws water up from the ground.
Slump Pumping
This is the simplest and the most common method of ground water control. The method operates by having the ground water collected using a sump and then the collected water pumped away from the excavation point.
Siphon Draining
This method works by having the water pumped by gravity along the siphon pipes. This method is often employed in sites with unstable slopes (Bear, 2012). The wells are installed in or on the unstable slopes, and then the water is pumped using the siphons that make use of the natural slope of the rates.
Deep Well Systems
This system consists of bored wells with each well using submersible pump. As the water pumps through each of the bored wells, the ground water reduces creating a cone of depression.
Ejector System
This system operates like the deep wells system. The system is based on wells which fall lower than the groundwater level to allow for the safe working condition (Harr, 2012. The ejectors use air in the wells to create a vacuum that has the effect of drawing water out of the soil.
Structural Steel Frame Structure
Structural steel framing describes the creation of steel skeleton comprising horizontal beams and vertical columns. The skeletons are meant to provide the support for roofs, walling, and roof of structures (Harries, Peck & Abraham, 2009). Structural steel framing can be categorized into three main groups including the clear-span rigid frame structure, single slope frame style, and modular structural frame. The type of steel to use in a structure is dependent on the height of the structure, roofing type, intended building use, location of the structure and building width.
The steel frame structures are often used in high-rise buildings because of the strength speed of construction and low weight (Taranath, 2016). The structures are used in industrial buildings because of steel frame structure are economical in the sense that hey allow large pans at low cost. Steel frame structures can also be applied in warehouse construction, residential buildings and in the construction of temporary structures. The use of steel frames is preferred in modern construction works because of sustainability, reliability, and affordability. The specific advantages include steel being lighter than other materials like wood and concrete, steel frames allow for faster construction. The use of steel frames reduces the construction since the materials can be reused, steel is durable compared to other materials, steel structures can withstand high winds, fire, and seismic activities. Moreover, the faster construction allows for minimum costs. Steel is environmentally friendly that makes its use widely acceptable.
Pad Foundations
Pad foundations are mainly used in supporting individual or multiple columns to help to spread the load to the ground (McKenzie, 2013). This type of foundation generally has square or rectangular plans with the shape dependent on the arrangement of the columns and the nature of load to be transferred into the solid. The plan area of pad foundation is determined considering the permissible bearing pressures of the soil underneath (Chen, 2012). The other important factor in the design of pad foundation is the slab thickness that must be sufficient to ensure distribution of load. Pad foundation design consider other aspects of the nature of the load bearing support, the presence of water, ground conditions, accessibility, project timeframe and proximity to other structures. Types of pad foundations include combined and continuous. The tops of pad foundation can be flat or sloping.
Combined Pad Foundations
This type of pad foundation is adopted in areas close to a site boundary to allow for the balancing effect of internal columns to be incorporated.
Continuous Pad Foundation
This type of pad foundation exists when the pads and the columns that support are closely spaced (Chen, 2012). The continuous pads have reinforcements between pads to ensure longitudinal stiffness that helps in resisting differential settlement. Continuous pad foundation is mainly applied on grounds with poor bearing capacity.
Construction Process from Start to Finish
Plans, Financing and Selecting a Contractor
After generating the idea to raise a structure, construction begins by hiring a competent contractor to assist in planning and guiding the development. The constructor helps in determining the appropriate structure to build depending on the terrain of the setting and interest of the client.
2. Permits and Insurance
Construction requires permits from relevant authorities that govern locations where the building will be established. Accessing permits from the city, state and council governments ascertain that the constructor is approved and engaging in a legal activity that does not compromise lives. Insurance, on the other hand, secures the building and builders from any unfortunate events that might occur in the construction process.
3. Site Preparation
Site preparation stage encompasses ascertaining that the terrain is fit for excavation depending on the structure to be established. The preparation further involves arranging for shipment of materials, putting temporary structure to store important materials and house staff. The contractor also ensures that the site has an efficient supply of power, water and properly aerated to support human survival and protect building material that can be affected by moisture such as cement.
4. Foundation
Laying a foundation of a structure is a complicated process that involves the use of various materials and techniques to root the building against destruction. Foundations are mostly built from concrete to help the building hold the earth firmly. Foundations are enhanced by rebar or wire mesh that helps in increasing the tensile strength of the foundation to prevent it from damages such as cracks as explained by Osborn (2012). The contractor may also use materials such as in-floor heating and complete the foundation by laying a cement floor.
5. Framing
Framing involves using either timber or steel to establish the skeleton frames of the building where the walls shall be attached.
6. Roofing, Siding, and HVAC
The
