2.1 Road construction resources

Road construction resources are the materials, people and machines that must be planned, obtained, organised and controlled to build a road to the required standard, on time and within budget. Roads use very large quantities of earth, gravel, stone and bitumen, need teams ranging from engineers to labourers, and depend heavily on heavy plant such as graders, rollers and pavers. Poor planning of any one resource, such as a shortage of suitable gravel, an idle grader waiting for water bowsers, or too few labourers for drainage works, delays the whole project and increases costs. Example: a contractor upgrading a 5 km gravel road to bitumen standard for a county roads department in Kakamega prepared a resource schedule showing when each material, labour gang and machine was needed, which kept the plant working continuously and completed the job two weeks early.

2.1.1 Materials resources

Materials resources are the natural and manufactured materials used to build the layers, drainage structures and furniture of a road, from the earthworks and gravel layers to the bituminous surfacing, culverts, kerbs, signs and markings. They usually form the largest part of the cost of a road, and their quality directly determines how long the road lasts, so they must meet the specification and be tested before and during use. Materials management covers identifying suitable sources, testing, ordering, delivering, storing, using and recording materials so that the right quantity of the right quality is available when needed. Example: before work started on an access road for a tea factory in Kericho, the materials engineer tested gravel from three borrow pits and approved only one that met the plasticity and strength requirements for the sub-base.

Common Road Construction Materials

Sources of Road Construction Materials

• Borrow pits: Excavated pits near the road provide gravel and fill, reducing haulage distances.
• Quarries: Rock quarries produce crushed stone for base layers, surfacing chippings and concrete.
• Cutting on the road line: Suitable material excavated from road cuts is reused as fill on embankments.
• Commercial suppliers: Cement, bitumen, steel and precast units are bought from manufacturers and distributors.
• Recycled materials: Milled asphalt and crushed concrete can be reused in new road layers where suitable.
• Water sources: Rivers, boreholes and dams supply water, subject to permits from the water authorities.

Steps in Managing Road Construction Materials

1. Determine requirements: Calculate the quantities of each material from the drawings and bill of quantities.
2. Identify and test sources: Locate borrow pits, quarries and suppliers, and test samples for compliance with the specification.
3. Obtain approvals and permits: Get the engineer's approval of sources and any permits for borrow pits, quarries and water abstraction.
4. Plan deliveries: Schedule deliveries to match the construction programme and avoid shortages or excessive stockpiles.
5. Receive and inspect materials: Check quantity and quality on delivery and reject non-complying materials.
6. Store materials properly: Stockpile aggregates on prepared ground, store cement dry and keep bitumen safely away from fire risks.
7. Control usage: Issue and record materials used on each section and compare with planned quantities.
8. Test during construction: Carry out routine tests on materials and completed layers.
9. Restore borrow pits: Reshape, cover with topsoil and rehabilitate borrow pits after use.

Worked Example: Gravel Required for a Base Layer

A road 1 km long has a gravel base 7.0 m wide and 150 mm (0.15 m) compacted thickness. The ratio of loose to compacted volume is 1.3. Trucks carry 10 m³ of loose gravel. Calculate the loose gravel required and the number of truckloads.

Compacted volume = Length × Width × Thickness

Compacted volume = 1,000 × 7.0 × 0.15

Compacted volume = 1,050 m³

Loose volume = Compacted volume × 1.3

Loose volume = 1,050 × 1.3

Loose volume = 1,365 m³

Number of truckloads = Loose volume ÷ Truck capacity

Number of truckloads = 1,365 ÷ 10

Number of truckloads = 136.5, say 137 trips

2.1.2 Labour and workforce management

Labour and workforce management is the planning, recruitment, organisation, supervision, motivation and welfare of all the people working on a road project, from engineers and supervisors to plant operators, artisans and labourers. Even on highly mechanised projects, people decide how resources are used, and on labour-based projects, such as those promoted under Kenya's Roads 2000 approach, local workers carry out much of the earthworks, drainage and gravelling by hand, creating employment in rural areas. Good workforce management ensures the right number of people with the right skills are available at the right time, working safely and productively, and paid fairly and on time. Example: a contractor improving rural access roads for a county roads office in Kitui recruited and trained local youth and women for ditching and culvert installation, organised them into gangs with daily task rates, and completed the drainage works on schedule while injecting over Ksh 3 million in wages into the community.

Categories of Road Construction Workforce

Functions of Workforce Management

• Workforce planning: Estimating the numbers and skills needed for each activity from the programme and quantities.
• Recruitment and selection: Hiring qualified staff and local labour fairly, following labour laws and any local content requirements.
• Training and induction: Inducting all workers on safety, site rules and their tasks, and training them in specific skills.
• Organisation into gangs: Grouping workers into teams with clear leaders, tasks and targets.
• Supervision and productivity control: Setting daily tasks, monitoring output and correcting poor performance.
• Health, safety and welfare: Providing PPE, first aid, drinking water, sanitation and safe working conditions.
• Payment and records: Keeping accurate attendance and output records and paying wages promptly.
• Industrial relations: Handling grievances, discipline and communication fairly to avoid disputes and stoppages.

Steps in Planning the Workforce for a Road Activity

1. Identify the activities: List the activities, such as bush clearing, ditch excavation and culvert installation.
2. Determine quantities: Obtain the quantity of work for each activity from the bill of quantities.
3. Establish productivity rates: Use standard task rates, such as cubic metres of excavation per worker per day.
4. Calculate labour requirements: Divide quantities by productivity to find the person-days needed.
5. Decide the duration and gang size: Determine how many workers are needed to finish within the programmed time.
6. Recruit and train workers: Hire workers and give induction and skills training.
7. Allocate tasks and supervise: Assign daily tasks to gangs and supervise output and quality.
8. Monitor and adjust: Compare actual output with plans and adjust gang sizes or methods as needed.

Worked Example: Labour Requirement for Ditch Excavation

A section of road requires 900 m³ of side ditch excavation by hand. Productivity is 3 m³ per worker per day, and the gang has 25 workers paid Ksh 600 per day. Calculate the person-days, duration and labour cost.

Person-days = Quantity ÷ Productivity

Person-days = 900 ÷ 3

Person-days = 300 person-days

Duration = Person-days ÷ Number of workers

Duration = 300 ÷ 25

Duration = 12 days

Labour cost = Person-days × Daily wage

Labour cost = 300 × 600

Labour cost = Ksh 180,000

Health, Safety and Welfare of Road Workers

• Personal protective equipment: Provide helmets, high-visibility vests, boots, gloves and dust masks.
• Traffic management: Protect workers from passing traffic with signs, cones, barriers and flagmen.
• Safe plant operation: Keep workers away from moving machines and use banksmen when reversing.
• Welfare facilities: Provide drinking water, toilets, shade and first aid kits.
• Working hours and rest: Plan reasonable working hours and rest breaks, especially in hot weather.

2.1.3 Equipment and machinery

Equipment and machinery are the plant, vehicles and tools used to clear, excavate, haul, spread, compact and surface materials during road construction. Mechanised equipment allows large quantities of earth and gravel to be moved and compacted quickly and to a high standard, but it is expensive to buy, hire, operate and maintain, so the right machines must be selected, matched to each other and kept working productively. Equipment management covers selecting suitable plant, planning its use, matching machines such as excavators and trucks, maintaining them and controlling their costs. Example: on a road rehabilitation project for a sugar company's outgrower roads in Mumias, the contractor matched one excavator with four tipper trucks after calculating cycle times, so that neither the excavator nor the trucks stood idle.

Common Road Construction Equipment

Factors Influencing Selection of Equipment

• Nature of the work: The activity, such as clearing, excavation, haulage or compaction, determines the type of machine.
• Quantity of work: Large volumes justify bigger, high-output machines, while small jobs suit smaller plant or manual methods.
• Soil and material type: Clay, sand, rock and gravel need different excavating and compacting equipment.
• Haul distance: Short hauls may suit dozers or loaders, while long hauls need trucks.
• Site conditions: Terrain, access, space and ground bearing capacity affect the choice of tracked or wheeled machines.
• Cost of ownership or hire: Purchase, hire, fuel, operator and maintenance costs must be compared.
• Availability of parts and skilled operators: Machines with local support and trained operators reduce downtime.
• Programme requirements: The time available determines the output and number of machines needed.

Steps in Managing Road Construction Equipment

1. Plan equipment requirements: Determine the types, numbers and timing of machines from the programme.
2. Decide whether to buy or hire: Compare the costs and availability of owning and hiring each machine.
3. Match machines: Balance the outputs of loading, hauling, spreading and compacting equipment to avoid idle time.
4. Mobilise and inspect: Bring machines to site, inspect them and confirm operator competence.
5. Carry out daily checks: Have operators check fuel, oil, water, tyres, brakes and safety devices before each shift.
6. Record usage: Keep logbooks of working hours, idle time, fuel and breakdowns.
7. Maintain and repair: Service machines according to the manufacturer's schedule and repair faults promptly.
8. Control safety: Enforce safe operating practices, reversing alarms and banksmen.
9. Demobilise: Remove machines from site when their work is complete to avoid unnecessary costs.

Worked Example: Matching Trucks to an Excavator

An excavator loads gravel at 60 m³ per hour. Each tipper truck carries 10 m³ and takes 30 minutes for a complete cycle of loading, hauling, tipping and returning. Calculate the number of trucks needed.

Trips per truck per hour = 60 minutes ÷ Cycle time

Trips per truck per hour = 60 ÷ 30

Trips per truck per hour = 2 trips

Output per truck = Trips per hour × Truck capacity

Output per truck = 2 × 10

Output per truck = 20 m³ per hour

Number of trucks = Excavator output ÷ Output per truck

Number of trucks = 60 ÷ 20

Number of trucks = 3 trucks

Maintenance of Road Construction Equipment

• Daily maintenance: Operators check fluid levels, greasing points, tyres, tracks, lights and alarms before work.
• Preventive maintenance: Machines are serviced at set hours of operation, including oil, filter and part changes.
• Breakdown repairs: Faults are repaired promptly by mechanics to reduce downtime.
• Record keeping: Maintenance records track service history, costs and recurring faults.
• Safe parking and security: Machines are parked on firm ground, secured and protected from theft and vandalism at night.

Chapter Summary

This chapter explored the essential resources required for road construction, including material selection, effective labour management, and the use of appropriate equipment and machinery. It examined how to interpret various construction drawings by understanding different types, symbols, abbreviations, and the importance of scale and accurate measurement. The discussion on levelling activities covered the different types of levelling methods and the instruments used to ensure precise ground profiling. The chapter detailed the profile layers of a pavement, describing the roles of the subgrade, subbase, base course, binder, and wearing course in creating a durable road structure. Maintenance of road structures was addressed by outlining the types of maintenance, inspection techniques, and common defects alongside their remedial measures. Finally, the chapter reviewed the range of construction tools and heavy machinery, emphasizing safety equipment, best practices, and the importance of regular equipment maintenance and operation to ensure efficient and safe road construction processes.