Causes of hazards robert acquaye

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ABSTRACT

Scaffolds are temporary platforms on which workmen carry out activities on site. They are essential when activities have to be executed above a required height. This makes them essential on every construction project. A large number of injuries on construction sites are however due to scaffolds, hence the need for this study.

This study sought to find the causes of hazards associated with scaffolds and recommend solutions to curtail the hazards on construction sites in Kumasi

This work commenced with the development a questionnaire to collect data on the extent to which scaffolds are used on site and the hazards that often occur with their use. This information was to help in recommending suitable solutions to the causes. Questions asked were based on the objectives of the study which were:

  • To examine the various types of scaffolds used on construction projects in Kumasi and ascertain their suitability for the works concerned;
  • To identify the causes of hazards associated with the use of scaffolds; and
  • To recommend solutions to prevent some of the hazards identified.

The results from the study were analysed using simple percentages and the ranking techniques. Results generally showed that scaffolds were used on construction sites in Kumasi. The most common type of scaffold however was the independent scaffold. Carelessness of workmen and overloading of scaffolds were also found to be the main causes of hazards on construction sites. If these were not prevented, they resulted in falls from scaffolds and striking by falling tools and material.

With the causes of hazards identified, it was realised that the best way to curtail these hazards was regular checks on scaffolds before and after every use

Recommendations made to contractors included: provision of safety helmets to all workers on site and policies to ensure that workers adhered to these directives. It was also recommended that tags and sign post be provided on scaffolds to caution workers on incomplete scaffolds and also for directions on site. Contractors were recommended to undertake training schemes for workmen periodically.


INTRODUCTION

1.0 BACKGROUND INFORMATION

The Occupational Safety and Health Administration, estimates that 2.3 million construction workers, or 65 percent of the construction industry work on scaffolds frequently. Protecting these workers from scaffold-related accidents would prevent 4,500 injuries and 50 deaths every year, at a savings for American employers of $90 million in workdays not lost

Hazards generally have an effect on how workmen approach activities, more especially, if they realize that the management puts no practical solutions in place to resolve them. The New Zealand's Qualifications Authority defines hazards as those occurrences, processes, substances or situations as determined by the supervisor that are an actual or potential cause or source of harm associated with, but not limited to: process, activities, environment, equipment, materials, work organization, site and facilities. This definition suggests some element of danger which cannot be left unmentioned as an issue of prior concern on construction sites; these occurrences if left uncontrolled can result in injury or illness.

The construction industry is plagued with a number of these hazards, key among them is one caused by scaffolds. Chudley R. and Greeno R.(2001) defines scaffolds as temporary working platforms erected around the perimeter of a building or structure to provide a safe working place at a convenient height. They play an important role in construction activities especially when work is to be done at heights equal or greater than 1.500m. In construction of buildings, most works undertaken on site generally go beyond this height, hence the need to employ them. Scaffolds commonly used on construction sites include mobile scaffolds, birdcage scaffolds, suspended scaffolds and cantilever scaffolds. Different types of scaffolds serve various purposes on site. The choice depends on the nature of the activity being undertaken. An example is the mobile scaffold which provides access to restricted or small areas and where mobility is required.

Ensuring that workmen have adequate knowledge in the use of scaffolds is the duty of the management of the firm. When these safety measures are not put in place to prevent these occurrences, they tend to be the cause of most of the injuries and deaths on site.

1.1 PROBLEM STATEMENT

The construction industry faces a number of safety hazards; one of them being the hazards associated with workmen and materials on and around scaffolds. Scaffolds do more than just serve as temporary platforms. They are designed to aid skilled workmen do their jobs easily.

Improper selection and construction of the scaffolds endanger the workmen. Components collapse, break or even give way. Planks, boards, decks or handrails fail. In some cases, the entire structures fail. Workmen sometimes slip or fall on sound scaffolds. Other problems include overloading of scaffolds and inadequate bracing. Workmen working on scaffolds as well as those on ground stand the risk of being injured or killed when objects fall on them. Failure to inspect the structure before its use also poses a problem.

These hazards if not prevented cause injuries and damage to workmen and property on site which indirectly tends to delay some construction activities; the overall effect of this being an increase in the project duration and cost.

1.2 AIM

The aim of this study is to:

Investigate and find the various causes of hazards associated with use of scaffolds on sites in Kumasi and suggest preventive measures to be put in place to reduce or stop these occurrences.

1.3 OBJECTIVES

The study has the following objectives:

  • To examine the various types of scaffolds used on construction projects in Kumasi and ascertain their suitability for the works concerned;
  • To identify the causes of hazards associated with the use of scaffolds; and
  • To recommend solutions to prevent some of the hazards identified.

1.4 METHODOLOGY

The methodology will be based on the objectives set above. This will include:

  • Site visits to observe the employment of scaffolds and record findings;
  • Disbursement of questionnaires to the various stakeholders (management and site workers) to obtain information on the employment and use of scaffolds; and
  • Extensive literature review on the topic and find out the extent to which hazards relating to scaffolds occur and measures put in place to prevent them.

1.5 SCOPE

This research was limited to finding out the extent to which contractors employ the use of scaffolds in their general construction activities with special emphasis on buildings within the Kumasi metropolis.

1.6 ORGANISATION OF THE RESEARCH

The study will be organized in five chapters

  • Chapter One - Introduction; this chapter involved a brief background on causes of hazards associated with scaffolds in the construction industry.
  • Chapter Three - Research methodology; this chapter deliberated on the various methods used to collect data for the project.
  • Chapter Three - Research methodology; this chapter deliberated on the various methods used to collect data for the project.
  • Chapter Four - Analysis and discussion of data collected in the field survey. It involved drawing of graphs and tables.

LITERATURE REVIEW

2.0 DEFINITION OF SCAFFOLD

Chudley R. and Greeno R. (2001), defines scaffold as a temporary structure erected around the perimeter of a building or structure to provide a safe working place at a convenient height. Scaffolds are therefore temporary structures but their design follows the principles laid down for permanent structures. Hence there must be no deviation from the structural principles (Construction Industry Research & Information Association, CIRIA)

They are usually required when the working height or level is 1.50m or more above ground level. All scaffolds must comply with the minimum requirements and objectives of the Construction Health, Safety and Welfare Regulations, 1996.

2.1 IMPORTANCE OF SCAFFOLDS

The main reason for erecting a scaffold is to support a working platform from which work can be carried out in a safe and convenient manner. Sometimes however, scaffolds are used for purposes other than access, an example will be as false work supporting concrete pours. Because of the importance of scaffolds in providing access, they must be erected, altered or dismantled by experienced operatives under the immediate supervision of a competent person (CIRIA).

2.2 TYPES OF SCAFFOLDS

The Construction Industry Research and Information Association (CIRIA) outline the three main types of scaffolds as: independent scaffolds, putlog scaffolds and birdcage scaffolds. This classification is based on how they are supported and laid out.

2.2.1 Independent scaffolds

Independent scaffolds are generally independent of the structure against which they are erected in terms of vertical support. They are however usually tied to the structure to give horizontal support. They have two rows of standards, each row joined to ledgers which in turn support the transverse transoms. The scaffold is erected clear of the existing or proposed building but is tied to the structure at suitable intervals.

2.2.2 Putlog scaffolds

Putlog scaffolds rely on vertical support from the structure against which they are built. These scaffolds have an outer row of standards joined together by ledgers which in turn support the transverse putlogs which are built into the bed joints or perpends as the work proceeds. They are mostly encountered on building sites and are suitable for work in bricks and blocks (Chudley, 2004)

2.2.3 Birdcage Scaffolds

Chudley R. defines birdcage scaffolds as a form of independent scaffolds but typically used for access to soffits or ceilings. They consist of parallel rows of standards connected by ledgers in both directions. The whole arrangement firmly braced in all directions. The whole structure is designed to support a single working platform which should be doubly planked or underlined with polythene or similar sheeting as a means of restricting the amount of dust reaching the floor level.

2.2.4 Other types of scaffolds

Other types of scaffolds used in the construction industry include suspended scaffolds and mobile scaffolds.

2.2.4.1 Suspended scaffolds

Suspended scaffolds consist of one or more platforms suspended by ropes or other non rigid means from an overhead structure to give access to the façade of a building to carry out light maintenance work and cleaning activities. The cradles are manual or power controlled and can be in single units or grouped together to form a continuous working platform. If grouped, they are connected together to one another at their abutment ends with hinges to form a gap of not more than 25mm wide.

As a requirement, the suspension ropes and other connecting hardware on suspension scaffolds must be able to support without failure, at least six times the maximum load applied to them (Chudley, 2004)

2.2.4.2 Mobile scaffolds

A mobile scaffold is an independent scaffold that is freestanding and mounted on castors. Mobile scaffolds must be provided with information regarding use and erection. If the scaffolding is to be altered, the manufacturer or supplier can be contacted for additional guidance. All modular mobile scaffolds can be erected in accordance with manufacturer's specification. In setting up the scaffold, the height of a mobile scaffold, from the bottom of the scaffold to the working surface should be no greater than three times the minimum base, their heights however are measured from the floor to the level of the working deck, a secure internal ladder with a protected opening (for example, a hinged trap door) for access and egress should be used to and from the scaffold. Bracing at the base of the scaffold should be incorporated to provide greater stability. Before moving the scaffold, it should be ensured that;

  • There are no power lines or other overhead obstructions
  • The ground is firm and level
  • No person is on the scaffold
  • No equipment and material can be dislodged from the platform
  • The supporting surface is free from obstructions (a small obstruction may cause a mobile scaffold to overturn)

2.2.4.3 Special scaffolds

Special scaffolds are required when it is impractical or unadvisable to build up from ground level. Examples are repairs to a parapet wall and work on the upper levels of a tall structure. For special scaffolds, the structure itself must be sound enough to take the stresses involved in anchoring the scaffold. Some of these scaffolds include: truss out scaffolds and cantilever scaffolds

2.3 COMPONENTS OF SCAFFOLDS

Components of scaffolds include scaffold boards, fittings to the scaffolds, guard rails, bracings etc. These are standard for most scaffolds.

2.3.1 Scaffold Boards

Scaffold boards are usually 225mm wide by 38mm thick; the maximum span for a standard board is 1.5m. Smaller spans should be used if heavy loads are expected. Boards should be butted close together and not overlapped. This prevents tripping hazards. Board should be tied down in exposed situations. This is done with proprietary clips.(www.osha.gov)

Good foundations are essential. Often scaffold frameworks will require more than simple base plates to carry and spread the load. Scaffolding can be used without base plates on concrete or similar hard surfaces, although base plates are always recommended. For surfaces like pavements or tarmac, base plates are necessary. For softer or more doubtful surfaces, sole boards must be used, beneath a single standard sole board should be at least 1000cm2 with no dimension less than 220mm, the thickness must be at least 35mm. For heavy duty scaffold, much more substantial baulks set in concrete may be required. On uneven ground, steps must be cut for the base plates, a minimum step size of around 450mm is recommended. (www.osha.gov)

2.3.3 Fittings

Fittings are generally used to join the different components of the scaffold together. There should be careful inspection of the fittings to check if they are in good condition and free from excessive rust. The inside of a coupler should conform closely to the shape of the tube, nuts and threads should be undamaged. All distorted and damaged fittings should be disposed of. A variety of fittings are used when mounting scaffolds.

2.3.4 Guard rails

Scaffold platforms from which a person may fall need guardrails. These are mandatory if the person can fall more than 2m. The upper guard rail should be fixed inside the standards at a height of between 910mm and 1.15m above the level of the decking and any raised part of it. If the gap between the bottom of the guard rail and the top of the toe is greater than 765mm, a second lower guard rail or a higher toe board is required. Two guard rails are recommended in all situations. Brick guard rails may be used as an alternative to immediate guard rails.

2.3.5 Bracing

Bracing is provided on scaffolds to resist horizontal loads and to stiffen the structure. It prevents distortion of the rectangular grid of standards, transoms and ledgers which can otherwise sway and collapse.

2.3.6 Ties

Scaffolds are tied to the structure at a number of points resist inward and outward movement. Ties also serve to increase the capacity of the standards by providing effective lateral restraints. Ties should be positioned so that they will not have to be removed to allow the work to continue.

2.4 ERECTION AND DISMANTLING

Erection, modification and dismantling of scaffolds must be planned by competent personnel and carried out by experienced scaffolds. The scaffolds must remain stable at all times during erection and dismantling. A partially dismantled or partially erected scaffold must be barred from general use, ladders removed, and prominent warning notices displayed. This is done using scaffold tags. (www.osha.gov)

2.5 PROTECTIVE EQUIPMENT

Safety equipment used include: safety harnesses, safety nets, helmets and these help prevent hazards that are usually associated with scaffolds.

2.5.1 Safety harnesses and belts

Safety harnesses and belts should only be used as a last resort where it is impracticable to provide a satisfactory working platform, they should be a high degree allied to mobility and wearer comfort.

Selection of an appropriate safety harness or safety belt is important. Information and advice should be sought from the manufacturer. Whatever type is chosen, it should given a high degree of safety allied to mobility and wearer comfort. It must also be secured to a safe anchorage.

2.5.2 Safety net

Safety net needs to be provided for all work places above surfaces where the use of ladders, scaffolds, catch platforms, temporary floors, and safety lines is impractical. Safety net must extend eight (8) feet beyond the edge of the surface where employees are exposed. Nets should also be hanged not more than 25 feet below the work surface with sufficient clearance and contact with the surface or structures below. Safety net must be impact load tested prior to commencing operations. (CIRIA)

2.6 HAZARDS

A hazard is the potential for harm. In practical terms, a hazard is often associated with a condition or activity that, if left uncontrolled can result in an injury or illness. Identifying hazards and elimination or controlling them as early as possible will help prevent injuries and illnesses. (www.osha.gov)

2.6.1 Hazards associated with scaffolds

Common hazards associated with all scaffolds according to the Occupational Health and Safety Administration (OSHA) includes:

Falls from elevation; due to lack of fall protection, collapse of the scaffold caused by instability or overloading, being struck by falling tools, work materials or debris; and electrocution; principally due to proximity of the scaffold to overhead power lines.

The Department of Employment & Industrial relations of the state of Queensland also classifies hazards under the following:

2.6.1.1 Work near power lines

Care must be taken when scaffolding work is close to bare and insulated electrical lines and hidden cables. When work is to be performed around electrical parts, precautions should be taken.

2.6.1.2 Mobile plant and traffic

Mobile plant and vehicular traffic are hazards which can potentially affect worker safety and the use and structural integrity of scaffolds. When using them, it should be ensured that scaffolding does not have any necessary protrusion such as over length transoms, putlogs and tie tubes. Also barricades, signs, posts, buffer rails, guards or concrete or timber kerbs should be used to prevent traffic from coming into contact with the scaffold.

2.6.1.3 Mixing and matching of scaffold components

Components from different manufacturers or suppliers while looking compatible are often of different dimensions and tolerances. Mixing and matching incompatible scaffold components can lead to difficulties in disassembly which in turn may increase the risk of injury, increase wear on the components, and affect the load capacity of the scaffold

The following controls can be used to prevent or minimize the risk of injury and scaffold collapse due to the incorrect mixing and matching of components.

Not mixing scaffolds from different manufacturers, unless an engineer approves that:

  • Using components that are of compatible size and strength;
  • Using components that have compatible deflection characteristics; and
  • Fixing devices are compatible.

2.6.1.4 Falling objects

There are measures that relevant persons and principal contractors must implement to prevent or minimize exposure to the risk of death or injury to persons, including workers, from construction work where an object could fall on or otherwise hit persons during the work.

Under the Work, Health and Safety (WHS) Act, obligation holders, including relevant persons and principal contractors must ensure the workplace health and safety of themselves and others is not affected by the conduct of their business or undertaking. This obligation includes preventing or minimizing exposure to the risk of death or injury from falling objects. The following are examples of control measures that may be used to prevent or minimize exposure to the risk of being hit by falling objects.

  • Establishing exclusion zones around scaffolding and adjoining areas to prevent unauthorized persons from accessing the area;
  • Using perimeter containment screening, scaffold fans, hoardings or gantries for containment of falling objects;
  • Erecting and dismantling scaffolds in built-up areas during quiet times; and
  • Not dropping materials from a scaffold - but by use of mechanical hoists to move materials

Attaching danger tags and warning sign such as 'Keep Out', 'Falling Objects', and 'Danger - Incomplete Scaffolding' in obvious locations to warn persons of hazards.

2.6.2 Hazards in the construction industry in Malaysia

"Statistics have shown that the number of fatalities and permanent disablement cases due to accidents at the Malaysia construction sites is one of the highest as compared to the other sectors. Even though the number of accidents is decreasing the benefits paid to the accident victims are ever increasing. Hence there is an urgent need to mitigate this problem." (A. Hamid, A. Rahim and others, Hazards at Construction sites, 2003).

There are three basic steps that should be taken namely; identifying the hazard, accessing the risk and controlling the risk to ensure a safe and conducive working condition. Implementation of effective hazard control methods may require different approaches due to changing working environments at the construction sites. Latest technology employed at site had wiped out traditional methods of construction and consequently introduced new types of hazards to the industry.

The study determined twelve (12) major groups of hazards in relation to works at construction sites such as power access, equipment, ladder, scaffolds, roof work, manual handling, plant and machinery, excavation, fire and emergency, hazardous substances, noise, protective clothing and protection to public. The study was conducted on 140 construction sites and the results showed that the most common hazards for the project around the study area were associated with the protective clothing, noise, fire & emergency and scaffolds.

2.6.3 Hazards on construction sites in the United Kingdom

Work related accidents with scaffolds generally fit one of three categories; collapses of scaffolds; falls from scaffolds; and falling objects from scaffolds. In the UK across the period 1989 to 1993, there were 345 scaffold collapses, 3738 falls from a scaffold and 1304 injuries from objects falling from scaffolds (Health and Safety Commission, 1993). A small number of studies have examined the immediate causes behind scaffold collapses and injury on or around scaffolds. An internal report by the Health and Safety Executive (2001) identifies the following leading causes of collapse across all scaffold types (in order of frequency): deficient ties to the building (28%); overload (25%); faulty components (13%); deficient bracing (9%); deficient foundations (6%). In the same study, tube and fitting scaffold comprised 52% of all cases; deficient ties were again leading cause of collapse for these scaffolds.

Other data for the United Kingdom come from the National Access and Scaffolding Confederation (NASC) in the form of annual statistics for accidents and incidents experienced by its members. In its most recent report (NASC, 2001), 110 companies were surveyed with an estimated combined total of 10,779 employees, and an estimated coverage of over half the total number of scaffold operatives in the industry. A total of 253 cases, one fatality amongst them were reported for a one year period. Accidents included falls of persons (22%, including one fatality); falls of materials (13%), handling of materials (26%); and "other site accidents" (33%). Of the 56 falls from height, 19 were from the scaffold structure, 7 were from a working platform, gangway, trestles, cradles, boatswains chairs ", 9 were from ladders, 3 were falls in yard and 18 were other (from walls, roof, rope, lorry)". The 33 cases of falling material included 22 from scaffold and 11 other falls of materials.

2.6.4 Hazards on construction sites in the United States

In the United States, Fattal, Mullen, Hunt and Lew (1980) categorized 143 work related scaffold incidents according to what the investigators judged as the primary cause. The records were selected from databases of the Bureau of Labour Statistics and the Occupational Safety and Health Administration (OSHA). For fatal cases, the failure or lack of guard rails was a frequent cause, followed by problems with connections (i.e. couplers), aspects of the work environment (e.g. weather) and anchors (i.e. ties). For non-fatal cases, anchors and connections emerged as the most common primary faults.

In their report, Fattal et al (1980) referenced an unpublished study by the Bureau of Labour Statistics that describes 801 cases involving all types of scaffolds. In 27% of cases the event was "person fell - nothing happened to scaffold". Other leading causes included "plank slipping" (16%), "plank breaking" (8%), "support poles tilting or tipping over" (7%), "wheels on bottom of the scaffold rolling" (6%), "cross bracing giving way" (6%) and "anchoring into structure giving way" (6%). Data from this study is given in table 2.6 alongside the Fattal et al data.

Table 2.6 causes of scaffold incidents

2.6.5 Hazard on construction sites in Ghana

In Ghana, the construction industry ranked second to the manufacturing industry with a total of 1108 reported cases of fatal accidents between 1974 and 1975. Statistics from the Ministry of labour and social welfare over the period 1975 - 1990 also indicated that construction contributed about 20 %( 2379) of the total number of 53613 reported cases of fatal accident. A total amounting to ? 513,396,064.58 was paid as compensation to victims whose cases were documented during the period.(Ministry of labour and social welfare report as cited in Isaac Quamn, July, 2000).

Hohoabu (1996) in his paper titled "Making construction work safe for work in Ghana" noted the causes of hazards as follows:

  • Falls due to height; and
  • Collapse of scaffold;

Scaffold and ladder accidents account for one of the most fatal degrees of accidents in the construction industry in Ghana (Asamoah, 1986)

2.6.6 Scaffold related injuries

Falls are the leading cause of disabling injury and death in the construction industry (Jacob Feld and Kenneth LC (1997) Construction failure). Falls represent 23 percent of all construction injuries and one-third of all fatalities. As in the case for accidents in general, most falls are preventable. Most of these accidents are as a result of bad construction or lack of maintenance. Many fatal scaffolding accidents are due to planks or supports give away; this is also the most common cause of non fatal injuries on scaffolds as well. Many injuries and fatalities involve employees being hit by objects falling from above. Amazingly, so many of these accidents and fatalities can be avoided with proper safety policies and maintenance of the construction site (Construction site Accidents, 2004)

2.6.7 Prevention of hazards

The Health and safety toolkit (2002/03) gives a check list to help prevent scaffolding hazards. Some of these are outlined below:

  • Are scaffolds erected, altered and dismantled by competent people?
  • Are all uprights provided with base plates (and, where necessary, timber sole plates)?
  • Is the scaffold secured to the building or structure in enough places to prevent collapse?

These questioned when thoroughly answered before work on the scaffolds begin; help reduce the occurrence of hazards on site.

The health and safety at work act, 1974 places a particular duty on employers to ensure provision and maintenance of safe access to and from any place of work under the employer's control. Employees are required to report any defects and must not interfere with, or misuse, equipment supplied.

The construction (design and management) regulations, 1994, place duties on clients, designers, planning supervisors and contractors to focus on health and safety matters throughout all stages of a construction project - from conception, design and planning through to the execution of works on site and subsequent maintenance, repair and demolition. Access requirements therefore must be considered from the outset and be included in the safety plan required by these regulations. Furthermore, these regulations also demand that the equipment used for access is:

  • Suitable;
  • Of sufficient quality for its purpose;
  • In good condition; and
  • Properly installed and maintained. 
  • Other regulations including the management of health and safety at work regulation, 1992, and the provision and use of work equipment regulations, 1992, also require that equipment:

  • Is suitable for its intended use;
  • Takes working conditions and hazards in the workplace into account;
  • Is properly maintained.

METHODOLOGY

3.0 INTRODUCTION

Based on the aim of the study, an appropriate sampling technique was used. This technique wa used to select construction sites employing the use of scaffolds on their sites. The availability and the ease with which they can be located were also considered. Questionnaires were used to gather information from the site engineers/foremen on sites employing the use of scaffolds.

3.1 PRELIMINARY SURVEY

The project targeted those currently using scaffolds on their sites. A survey was conducted to determine the level of use of scaffolds, and the types commonly used by contractors. This information indicated whether the project would make the desired impact and also ensured that the questionnaires were developed to meet the aim of the study.

3.2 SAMPLING

The purposive sampling technique was used; focusing on construction sites employing the use of scaffold since this met the purpose of the study. The questionnaires were floated based on the availability of the construction sites. The choice of method was partly due to limitations of time and resources hence a size of 15 contractors was considered

3.2.1 PURPOSIVE SAMPLING

In using this technique the choice of sample was based on the purpose of the study. Purposive sampling involved studying the entire population of contractors in Kumasi currently using scaffolds on their sites. Since this population size could not be defined, 15 contractors were selected based on the aim of the study.

3.3 ADMINISTRATION OF QUESTIONNAIRES

Questionnaires once developed were administered to the foremen/site engineers on site individually. They were administered personally to classify any misunderstanding. Though this was time consuming, it ensured that the questionnaires were answered appropriately and made the analysis easier. Data was collected through the administration of questionnaires

3.4 DATA COLLECTION & ANALYSIS

Findings obtained from the survey were documented after which data collected was analyzed

DATA AND ANALYSIS OF DATA

4.0 INTRODUCTION

This chapter gives account of how the field data obtained from administered questionnaires were analysed and discussed. The data obtained were analyzed using the ranking techniques and simple percentages. The results were diagrammatically presented as possible. A total number of 15 questionnaires were distributed and out of which 15 were received. The responsive rate was 100%.

4.1 FIELD DATA COLLECTED

Most of the questionnaires administered were retrieved within a 7 day period. In most cases however, the contractors filled them immediately upon receipt. This thus gave the researcher the opportunity to further seek the opinion of some of the contractors on areas where the questionnaire could not cover.

4.2 RANKING

As part of the questionnaire, an attempt was made to ascertain the opinion of respondents on some issues. In these cases, three factors were considered(High, Moderate, low), each respondent was asked to rank them in order in which each of them was thought to be a possible factor that affects those particular questions.

A weighting method was used to evaluate the result from the survey. Each factor was considered either:

High (H) - weighted 3

Moderate (M) - weighted 2

Low (L) - weighted 1

The equations used were:

3H + 2M + 0L = W

Where:

H, is the number of times the factor is ticked "High"

M, is the number of times the factor is ticked "Moderate"

L, is the number of times the factor is ticked "Low"

P = W/3Q

Where:

P is the relative importance index;

Q is the number of respondents in that category of statistic.

4.3 TYPES OF SCAFFOLDS USED

In line with the first objective of the study, Questions which sought to find out the types of scaffolds contractors use to accomplish various tasks on their sites were analysed.

From the results of the field data, it was realised that 100% of the respondents admitted they employ scaffolds in their activities on site. A number of respondents; 40% were found to be using independent scaffolds on site. Other respondents; 13% employed a combination of scaffolds. These combinations were the next popularly used scaffolds on site. They were:

  • independent and putlog scaffolds;
  • Putlog and mobile/tower scaffolds;
  • independent, putlog and birdcage scaffolds; and
  • Putlog, suspended and mobile/tower scaffolds.

The least used scaffolds on site were a combination of independent, putlog and mobile/tower scaffolds representing 7% of the total respondents.

The greater number of respondents using independent scaffolds was attributed to their availability and suitability for the job description. Different combinations of scaffolds on site were as a result of varying activities on site and the need to use the right type of scaffold to prevent injuries.

4.4 SUITABILITY OF SCAFFOLDS FOR WORKS

Here the objective was to find out the appropriateness of the types of scaffolds contractors use for the various activities undertaken on site.

From the results of the field data, it was realised that 53% of respondents chose independent scaffolds as the most suitable. The greater number of respondents using independent scaffolds was attributed to their availability and because it suits the job description.

The next important scaffold used on site was a combination of putlog and mobile/tower scaffolds making 23% of the responses. This was followed by a combination of independent and putlog scaffolds which was 13% of the responses. The least important scaffolds used on site was a combination of independent, putlog and mobile scaffolds which was 7% of the responses.

4.5 HAZARDS THAT OCCUR WITH THE USE OF SCAFFOLDS

Respondents were asked to rank the hazards that occur with the use of scaffolds in line with the objectives of the study.

A high number of respondents: 84%, choose striking by falling tools and materials as the main hazard that occurs with the use of scaffolds on site. 13% of the respondents however said destruction of property was also a hazard that occurred often on site. 4% of the respondents also said falls from scaffolds was a cause of hazards on site.

Collapse of scaffolds and electrocution ranked least as the hazards that occur with the use of scaffolds on site.

The high number of respondents choosing striking by falling tools and materials was attributed to the fact that workmen use tools for most kinds of activities on scaffolds and because these tools are handheld, most of them slip from their hands. The low response for collapse of scaffolds and electrocution was also attributed to the fact that most respondents inspect scaffolds regularly before use and also because scaffolds are not erected near electricity lines.

Table 4.5.1: hazards that occur with use of scaffolds

Factor

H

M

L

W

P%

Rank

falls

0

1

14

2

4

3rd

Collapse of scaffold

0

0

15

0

0

4th

Striking by falling tools and materials

8

7

0

38

84

1st

destruction of property

0

3

12

6

13

2nd

Electrocution

0

0

15

0

0

4th

4.6 CAUSES OF HAZARDS ASSOCIATED WITH SCAFFOLDS

In achieving one of the objectives stated in this study. The question sought to identify the various causes of hazards on site. The ranking method was used for the analysis.

Respondents indicated that carelessness and overloading of scaffolds were the leading causes of hazards on construction sites. They ranked 1st with a relative importance index of 91%. Obstructed walkways with a relative importance index of 87%, followed as the next cause of hazards. These causes were greater than other causes like mixing of incompatible scaffold components, use of damaged components, inadequate bracing, absence of guard-rails on scaffolds, poor scaffold foundation and improper erection of scaffolds with relative indices of 82%, 80%, 76%, 73%, 69% and 49% respectively Respondents however chose close proximity of scaffolds to electricity as the least cause of hazards on the construction site. From reasons that were given and from observation, the scaffolds were not erected near electricity lines.

The choice of carelessness and overloading of scaffolds as the highest cause of hazards could be attributed to the fact that generally there was no supervision on how workmen conducted activities on the scaffolds.

Respondents generally indicated the magnitude of each of these causes of hazards, this is summarised in Table 4.6.1

Table 4.6.1: Ranking of causes of hazards

Factor

H

M

L

W

P%

Rank

Improper erection of scaffolds

5

3

7

21

47

8th

Carelessness

11

4

0

41

91

1st

Mixing of incompatible scaffold components

7

8

0

37

82

3rd

Overloading of scaffolds

13

1

1

41

91

1st

Absence of guard-rails on scaffolds

7

6

2

33

73

6th

Obstructed walkways

9

6

0

39

87

2nd

Poor scaffold foundation

7

5

3

31

69

7th

Use of damaged scaffold components

10

3

1

36

80

4th

Inadequate bracing

6

8

1

34

76

5th

Close proximity of scaffolds to electricity

0

11

13

22

49

9th

4.7 PREVENTION OF HAZARDS

This question sought to find out the measures contractors put in place to prevent hazards on site.

From the analysis of data a greater number: 40%, of the respondents chose regular inspections as the principal way in preventing hazards on site. 13% of respondents also chose a combination of different activities as means by which hazards were prevented on site. These were:

  • Netting and regular inspection;
  • Regular inspection, sanction and inspection before use; and
  • Regular inspection, sign posting and inspection before use. 
  • The least important way of preventing hazards on site was a combination of activities with 6.7% of the response, these were:

  • Netting, regular inspection, sign posting, sanctions, and inspection before use;
  • Regular inspection, inspection before use; and
  • Netting and regular inspection.

It was observed that on construction sites inspection was done before and after erecting the scaffold. Damaged components are separated from the ones in good condition. The high response in favour of regular inspection is hence realistic.

Table 4.7.1: Prevention of hazards

Prevention

Frequency

Percent

Regular inspection

6

40.0

Netting, inspection, sign post, sanctions, inspection before

1

6.7

Regular inspection, inspection before use

1

6.7

Netting, regular inspection

2

13.3

Regular inspection, sanction, inspection before use

2

13.3

Regular inspection, sign posting and inspection before use

2

13.3

Netting, inspection, sanction, inspection before

1

6.7

Total

15

100.0

4.8 SAFETY PROTECTION EQUIPMENT

This objective sought to find out some of the safety protection equipments used by the respondents on site when mounting scaffolds. The choice of equipment had an effect on the hazards that occurred on construction sites.

A greater number of respondents chose a combination of: safety nets, guard rails, helmets, and safety boots as the most suitable safety equipments used often on site. This was followed by guardrails, safety nets and helmets as the suitable protection equipment. The least suitable protection equipments on site were a combination of:

Fall arrest, safety nets, guard rails, helmets, safety boots; and

Guard rails and safety nets.

4. 9 ACTIVITIES FOR SCAFFOLDS

This question sought to find out the some of the activities contractors use the scaffolds for. The choice of activities generally had an effect on the choice of scaffolds, hazards that occur and the preventive measures to be put in place.

The highest ranked activities were a combination of Access to upper floors, rendering of masonry, putting ceiling boards in place, electrical installation and putting cladding in place. Generally respondents on site employed scaffolds for activities that required working above a particular height

In brief the activities scaffolds are used for have been summarised in Table 4.9.1 showing all other activities respondents chose.

Table 4.9.1 Activities for scaffolds

Activities

Frequency

Percent

Painting, general access to upper floors and rendering

1

6.7

Painting, access to upper floors, rendering, fixing ceiling boards and electrical works

1

6.7

Painting and rendering

1

6.7

painting, access to upper floors, rendering, ceiling boards, electrical works, cladding

2

13.3

painting, access to upper floors, rendering, electrical works

1

6.7

Access, rendering, plumbing, cladding

2

13.3

Access to upper floors, rendering, putting ceiling boards in place, electrical, cladding

3

20.0

painting, rendering, cladding

2

13.3

Painting, general access, rendering

1

6.7

painting, access, rendering, ceiling, electrical, plumbing

1

6.7

Total

15

100.0

CHAPTER FIVE

CONCLUSION AND RECOMMENDATION

5.0 INTRODUCTION

This chapter gives a summary of findings in this study based on the aim of investigating and finding the various causes of hazards associated with use of scaffolds on sites in Kumasi and the preventive measures to be put in place to reduce these occurrences. Suggestions for further research and recommendations to contractors were also discussed.

5.1 SUMMARY

The research commenced with a set of objectives which have been addressed as follows:

1. To examine the various types of scaffolds used on construction projects in Kumasi and ascertain their suitability for the works concerned.

The most common type of scaffold used was the independent scaffold. The study also found that in most cases, contractors used a combination of scaffolds to enable them accomplish various tasks on site. The most common combination was putlog and mobile/ tower scaffolds. The contractors also confirmed the suitability of the independent scaffolds to their work on site with their responses.

2. To identify the causes of hazards associated with the use of scaffolds.

Some of the hazards identified however included: striking by falling tools and materials. This was the most common hazard identified. Other hazards identified were destruction of property, falls from scaffolds and collapse of scaffolds which was the least amongst the hazards identified. After identifying the hazards, the causes were then considered. Carelessness and overloading of scaffolds were the main causes of hazards on construction sites in Kumasi. Contractors however gave other causes like: Obstructed walkways, mixing of incompatible scaffold components, use of damaged components, inadequate bracing, absence of guard-rails on scaffolds, poor scaffold foundation and improper erection of scaffolds. The least cause of hazard was close proximity of scaffolds to electricity.

3. To recommend solutions to prevent some of the hazards identified.

In recommending solutions to prevent the hazard identified on site, the hazards identified and their causes were taken into consideration. Regular inspection of scaffolds was the best way to prevent hazards on site. Safety netting around scaffolds, sanction to guilty parties and sign posting were also considered as good ways to prevent hazards on construction sites. Some of the respondents use a combination of the prevention methods.

5.2 CONCLUSION

From the study, Independent scaffolds were found to be in popular use on sites in Kumasi. This was primarily because of their availability and the suitability for the job descriptions. In satisfying the aim of the study, the causes of hazards found were carelessness and overloading of scaffolds. These were found to be the main causes of hazards on site. From the study, it was realised that there was general lack of education with regards to the safety practices on site hence the reasons for the occurrence of these hazards. Other causes were however considered. These were obstructed walkways, use of damaged components, inadequate bracing, absence of guard-rails on scaffolds, poor scaffold foundation and improper erection of scaffolds.

5.3 RECOMMENDATION

After a careful analysis of the findings, the following recommendations were made:

Firstly, contractors must undertake training schemes for their workmen. This should be integrated with the activities that are accomplished using scaffolds to educate them on the use of scaffolds and dangers that may arise if they are not used in the right way.

Secondly, safety helmets must be provided for all workers on site and sanctions must be put in place to ensure that workers adhere to these directives.

Thirdly, tags and sign posts must be provided on scaffolds to caution workers on incomplete scaffolds and also for directions on site. This is to prevent workers from mounting and moving around incomplete scaffolds.

Finally, scaffolds must be checked to ensure that adequate bracings are in place. Faulty bracings should be removed and replaced. Other components like the clips, scaffold boards and base plates should be checked regularly

5.4 FURTHER RESEARCH

It is recommended as part of future project work, a research into enforcement of safety practices on sites in Kumasi. This must be done with respect to scaffolds the use of scaffolds on site.

1. Occupational health and Safety, ONSHA Report, 1984, http://www.inshhealth.com

2. Quamn Isaac, July 2000 - Towards the reduction of accidents on Ghanaian construction sites. Building Technology Department pages 28-30

3. Hohoabu, 1996 Making Construction work safe in Ghana, Ghana Institute of Engineers newsletter.

4. Asamoah James, 1986, Non- parametric statistical analysis on site accident- causation and findings

5. Ken Logan (2003), Absolutely Essential Health and safety Toolkit for the smaller construction contractor

6. Jacob Feld and Kenneth LC (1997) Construction failure

7. Chudley R. and Greeno R(2004), Building construction handbook(4th edition)

8. Construction site Accidents, 2004, http:// www.googlesearch.com

ANALYSIS OF QUESTIONNAIRES

Table 4.3.1: Types of scaffolds

Types

Frequency

Percentage

Independent scaffolds

6

40.0

Independent and putlog scaffold

2

13.3

Putlog and mobile/tower scaffolds

2

13.3

Independent, putlog and mobile/tower scaffolds

1

6.7

Independent, putlog and birdcage scaffolds

2

13.3

Putlog, suspended and mobile/tower scaffolds

2

13.3

Total

15

100.0

Table 4.4.1: Suitability of scaffolds

Types

Frequency

Percentage

Independent scaffolds

8

53.3

Independent and putlog

2

13.3

Putlog and mobile/tower scaffolds

4

26.7

Independent, putlog and mobile/tower scaffolds

1

6.7

Total

15

100.0

Table 4.5.1: hazards that occur with use of scaffolds

Factor

H

M

L

W

P%

Rank

falls

0

1

14

2

4

3rd

Collapse of scaffold

0

0

15

0

0

4th

Striking by falling tools and materials

8

7

0

38

84

1st

destruction of property

0

3

12

6

13

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