Road Maintenance Method Statement Including Cracks Potholes Patches Edge Breaks

Contractor will carry out the road maintenance and construction works in compliance with the technical specification and engineer’s instructions.

With the direction and instruction of the client/ consulting engineer, at the designated areas, the motor graders and excavators are used to clear, remove, and dispose all vegetation, silt and grubbing roots, down timber and other unacceptable materials.

Large trees and stumps within construction area is cut down by hand and then be transported and stockpiled at designated place directed by the Engineer.

Small vegetation, timber piles, roots, and silt is curved by excavators and then is transported to the spoil area directed by the Engineer.

The clearing and grubbing, unless otherwise instructed by the consultant, include also the removal of all roots, stumps, untidy vegetation, rubbish, garbage and to the extent that these materials are not, in the opinion of the Engineer, obstruct the future maintenance.

All unsuitable materials are wasted and re-spread at designated locations in a neat and orderly way as agreed by the consultant/client.

Where necessary works shall be composed of common, unsuitable excavation, and the excavation of bituminous materials. Roadway excavation includes the removal, hauling and proper utilization, or disposal of all excavated materials, the shaping of excavation and the preparation of exposed surfaces of excavation on the entire length of roadway.

The survey team marks all excavated locations, lines, level, grades, dimensions, and cross section, which is shown on the drawings and as directed by the client/consultant.

Channel Excavation

This work where required consists of excavation both inside and outside the right of way, where shown on the drawings, or specified in the Special Provision, or directed by the Engineer.

Work includes the proper utilization and hauling or disposal of all excavated materials, constructing, shaping and finishing all earthworks involved in conformity with the required alignment, levels, grades and cross sections.

Based on the drawing, the surveying engineer sets out the level line and measures the original ground elevation, then figure out the excavation depth according to the designed bottom elevation, and then mark it up with stakes.

During the construction or maintenance, the channel is kept drained as far as practicable and the work is constructed in a neat and workmanlike manner. All the unsuitable materials are transported to the spoil area, while the materials that could be used for sub-grade filling or slope block sodding and formation of embankments are stocked together nearby.

The channel sidelines are trimmed manually to ensure lines smooth and fluent.

Embankment Work

This work consists of the construction of embankment by furnishing, placing, compacting and shaping suitable material of acceptable quality obtained from approved sources in according with the roadwork specification, and to the lines, levels, grades, dimensions, and cross section shown on the drawings and as required by the consulting engineer.

Embankment filling materials are tested in accordance with the specification to determine the appropriate materials prior to execution. Not until approved by the Engineer, the filling shall not be started. Natural ground situated less than 1.5 m below the design surface of the road or side slopes, after proper clearing and grubbing or scarifying of existing road surface, are compacted to a depth of 150 mm, to not less than 90 % of the maximum dry density of the material as determined by AASHTO test method T180.

If unsuitable materials occur in some areas under embankment or in existing embankment, such materials are removed to levels as directed by the Engineer, the bottom of the excavation is compacted, and areas backfilled and compacted layer by layer with suitable materials.

Sub-base and Base Course Maintenance

The work consists of repairing sub-base and base course failure and spreading sub-base and base course in accordance with the specification and the drawings.

Subbase repair work consists of furnishing, placing and compacting sub-base material on a prepared and accepted sub-grade to the lines, levels, grades, dimensions and cross sections shown on the drawing and as required by the Engineer.

Based on the drawing, the engineer sets out the horizontal position of sub-base, determine the thickness of spreading, and then mark it up with stakes.

Prior to sub-base spreading, watering cart is used to wet the sub-grade to ensure the cohesiveness between them.

The sub-base is shaped, compacted and completed for at least 150 m ahead of the placing of the sub-base course material and subject to the requirements of the contract for the Engineer’s approval of the sub-grade before it is covered up.

Sub-base is spread in even layers not exceeding 150 mm after compaction.

Care is taken to prevent segregation, and oversized particles are hand-picked from the deposited layer prior to compaction.

Immediately after each layer has been spread and shaped satisfactorily, each layer is thoroughly compacted with suitable and adequate compaction equipment. Each layer is compacted to at least 95 % of the maximum dry density, as determined by AASHTO T180.

Base course work shall be composed of aggregate base of 6930 m3 and soil aggregate shoulders of 1200 m3. This work is determined to execute in accordance with the above method of sub-base.

Repairing/Maintenance of Bitumen Works

This work shall consist of repairing existing defective bitumen pavement, including bituminous surface treatment, longitudinal cracking, block cracking, patches, and edge breaks.

Bituminous Prime Coat

Work consists of the preparation for and application of a bituminous prime and blotting material to a previously prepared and untreated surface. via: earth sub-grade, crushed aggregate base course, cement or lime, stabilized base course, top of roadway shoulders, concrete bridge deck etc. in accordance with the specification and in close conformity with the lines shown in the Drawing or established by the Engineer.

Slow setting cationic emulsified bitumen is chosen as the prime coat, whose quantity and quality are in conformity with the specification.

Pre-distribution is done to check the consistency of bitumen:

• The prime coat is sprayed after clearing the cutting left over of existing defective pavement. A slight application of water is made if the surface is over dry.
• It is determined to execute by a bitumen distributor, which is fitted with a handheld, manually operated bar fed by a flexible line for use on areas too small to be satisfactory sprayed with the main bar.
• Before any bitumen distributor is used on the works, the calibration of the nozzle shall be checked in a series of field tests to maintain appropriate speeds for the proper application of the bitumen.
• During the progress of the work, it is sprayed uniformly at one time in accordance with the designated bitumen capacity in case of bitumen’s flowing to penetrate into the base course.
• Oil slick formed on the surface is not permitted.
• Once any omission occurs, remedial spraying is done manually.
• After the spraying, the traffic is strictly regulated in case of any vehicle or person passing through.
• No spraying is carried out on a wet pavement, while rain appears imminent or during high winds; the extra prime coat bitumen, which has not penetrated into base course, is cleared immediately.

Bituminous seal coat shall be applied to the execution of the prime coat as per the above steps.

Sealing Aggregate

Aggregate spreader is used in the execution of construction:

• The crushed stone aggregate is spread before emulsion breaking. To ensure a good cohesiveness between aggregate and bitumen, crushed stone aggregate is spread once emulsion stops flowing.
• Crushed stone aggregate is spread uniformly and not be overlapped, which cover the full pavement with no exposing bitumen.
• Manually remedial work is done when any local omission occurs.
• The crushed stone aggregate adheres to bitumen emulsion through rolling and integrates with it after its breaking.
• Where there is excess aggregate, the unsuitable is removed immediately to make the surface level uniform.
• Pneumatic-tired roller of 10 tons is used to compact, which is executed when the bitumen becomes fully black and emulsion has been breaking.
• One to two-time light rolling is done firstly and re-rolling be started after it is dry.

Repair of Cracks

This work applies to the repair of linear cracking, or narrow-sections of block cracking in accordance with the specification or otherwise directed by the Engineer.

Method of repair depends on the width of cracking and the area of block cracking.

Larger areas of block cracking are treated as patches.

The operation of preparing and filling cracks is completed in the same day to ensure open traffic on time.

For the linear cracking less than 2 mm:

• All cracks are cleaned out with compressed air (and a wire brush, if necessary), to remove all dust and loose particles.
• Cracks are dried with a heat gun, or similar, if moisture is present.
• After cleaning and drying, cracks are to be filled with a modified bituminous material or bitumen emulsion, having a viscosity low enough to enable it to be penetrated into the crack.

For the linear cracking less than 6 mm:

• All cracks are cleaned out with compressed air (and a wire brush, if necessary), to remove all dust and loose particles.
• Cracks are dried with a heat gun, or similar, if moisture is present.
• After cleaning and drying, cracks are to be filled with a modified bituminous material or bitumen emulsion, having a viscosity low enough to enable it to be penetrated into the crack.
• A single bituminous treatment surface (SBST) sealing coat, with a width of 20 cm regarding the cracks as the central line, is spread.

For the linear cracking more than 6 mm:

• Regarding the cracks as the central line, the excavation and removal of bituminous pavement within 15 cm from the line are completed.
• A cutting line, which has to be parallel or vertical with the central line of road pavement, is drawn by chalk in the fields intended to excavate before executing.
• Then, the cutting with a depth of 75 mm or otherwise directed by the Engineer is made along the drawn line in order to ensure longitudinal and leveling sides of the cutting groove straight.
• The materials of base course are loosened arid re-compacted and all unsuitable materials must be removed if any.
• A bitumen prime coat is spread manually.
• A double bituminous treatment surface (DBST) is spread.

Filling Potholes and Patch Repairs:

This work includes repair of potholes, patching, and areas of block cracking in all types of bituminous pavement.

It also includes the removal of all failed material, in the pavement course and, if necessary, below the pavement, until the root cause of the failure is removed.

The replacement of material is as high a standard as that which was originally specified for the pavement layer; the compaction, trimming and finishing of the surface of all patches shall be able to form a smooth continuous surface, level with the surrounding road.

For pothole and patch repair:

• A cutting line of a regular straight sided rectangular shape, which has to be parallel or vertical with the central line of road pavement, is drawn by chalk in the fields intended to excavate before executing.
• Then, the cutting with a depth of 75 mm or otherwise directed by the Engineer is made along the drawn line in order to ensure longitudinal and leveling sides of the cutting groove straight.
• The repair area is thoroughly cleaned with compressed air or other method approved by the Engineer to remove all dust or loose particles.
• Damaged or disturbed layers below the level of the bituminous construction is excavated into the shapes of benches, each of which is with a width of 20 cm, be repaired or replaced using material of the equivalent to original ones and be compacted in accordance with the Specification.
• A double bituminous treatment surface (DBST) is spread.
• The bituminous material chosen for the repair is to be applied or laid, and compacted in accordance with the relevant clause of the Specification.
• While placing the final layer, the mix is spread slightly proud of the surface so that after rolling, the surface is flush with the adjoining surface.
• If the area is large, the spreading and leveling are done using hand shovels and wooden straight edges.
• During the process of compaction, the surface is checked using 3 m straight edge and required camber or cross fall is maintained.

Repair of Edge Break

Damaged sections of the edges of carriageways or pave shoulders are removed and renewed with fresh material, as indicated on the contract drawings, using materials and a methodology as for the repair if potholes etc.

The adjacent earth verge or soil-aggregate shoulder is subsequently brought up to the level of the bituminous pavement or shoulder in order to protect future protection of the repair.

For Depressions in the Pavement

This work consists of depressions of bridge abutments and service pipes, wheel ruts and shoving.

As for these defective pavement, they are rectified by recourse to appropriate techniques as indicated on the contract detailed drawings, such as the application of a leveling course or courses, scarifying to remove excess material (subsequent to an overlay), or implementing a patch repair or full-depth reconstruction.

Repairing depressions less than 6 cm:

A cutting line of a regular straight-sided rectangular shape is drawn by chalk in the fields intended to excavate before executing.

Then, the cutting with a depth of 25 mm is made along the drawn line.

Finally, all bituminous material is carved out of sides of the cutting groove.

A bituminous tack coat is spread along the sides of the cutting groove.

The bituminous concrete then is spread and compacted.

For depressions more than 6 cm:

A cutting line of a regular straight-sided rectangular shape is drawn by chalk in the fields intended to excavate before executing.

Then, the cutting is made along the drawn line.

The sub-base, base course and DBST or AC (asphalt concrete) pavement are excavated into benches with a width of 20 cm one by one.

All loose material on the roadbed is also removed if any.

All materials, which is of the same as the original ones of existing layers are backfilled and compacted one by one in accordance with the Specification.

Repairing of Shoving:

Shoving is a type of small-localized failure of bituminous pavement, due to pick up of heavy vehicle on the soft bituminous surface treatment.

The method to repair this type of failure is as below steps:

• Cut the defect area in square
• Remove the defected bituminous surface treatment and other disturb materials.
• Clean the cut areas by air Compressor.
• Apply CRS-2 as per calculation rate for first layer is 1.80 liter / sq-m.
• Hand spreading of chip seal aggregate 19 mm as per calculation rate.
• In order to press the stone on to the binder, remove the stone so that their least dimensions are vertical and to achieve mechanical interlock between the stone, rolling should continue until the aggregate has been well embedded in the binder and uniformly textured surface is obtained.
• Apply CRS-2 as per calculation rate for second layer is 1.1 liter/ sq-m
• Hand spreading of chip seal aggregate 12.5 mm as per calculation rate.
• In order to press the stone on to the binder, remove the stone so that their least dimension are vertical and to achieve mechanical interlock between the stone, rolling should continue until the aggregate has been well embedded in the binder and uniformly textured surface is obtained.
• In case, third layer is required to carry out a same procedure as per second layer.
• In case of repaired surface is overlaid after repair works; only the fill with DBST on the lower part is needed and cut back to design level on the rough and hump of surfaces.

Repair of Base Course Failure

This work include repair of base course failure in all types of existing bituminous pavement.

It also includes the removal of all failed material, in the pavement course and, if necessary, below the pavement, until the root cause of the failure is removed.

The replacement of material is as high a standard as that which was originally specified for the pavement layer; the compaction, trimming and finishing of the surfaces of all patches are able to form a smooth continuous surface, level with the surrounding road.

• A cutting line of a regular straight sided rectangular shape, which has to be parallel or vertical with the central line of road pavement, is drawn by chalk in the fields intended to excavate before executing.
• Then, the cutting with a depth of 75 mm or otherwise directed by the Engineer is made along the drawn line in order to ensure longitudinal and leveling sides of the, cutting groove straight.
• The repair area is thoroughly cleaned with air compressor or other method approved by the Engineer to remove all dust or loose particles.
• Damaged or disturbed layers below the level of the bituminous construction are excavated into the shapes of benches, each of which is with a width of 20 cm, be backfilled using material of the equivalent to original ones with the depth of 20 cm and be compacted in accordance with the Specification.
• A double bituminous treatment surface (DBST) or AC is spread.
• The bituminous material chosen for the repair is to be applied or laid, and compacted in accordance with the relevant clause of the Specification.
• While placing the final layer, the mix is spread slightly proud of the surface so that after rolling, the surface is flush with the adjoining surface.
• If the area is large, the spreading and leveling is done using hand shovels and wooden straight edges.
• During the process of compaction, the surfaces level is checked using 3 m straight edge and required camber or cross fall is maintained.

Maintenance of Drainage and Protection Works

This work consists of cleaning existing drainage pipes along the road and existing channels through bridges, of which drainage pipes, which is less than 1 m diameter, used for the drainage pipeline of local residents along the road, are of difficulty to dredge because of their small aperture dimension and long pipeline that is out of reach, and channels through bridges are almost free-flowing.

As for protection works, it places slope protection block sodding against the road sections where the embankments are washed out seriously.

The blockage of debris and silts in existing drainage system and proposed solution method are submitted to the Engineer in accordance with site condition.

Not until the approval of the Engineer, the works of dredging are not executed.

As for the drainage pipes, it is suggested that they be jetted with high-pressure gun; channels are cleared up by hand while water level is in depression in dry season.

The washout of embankment and proposed protection method are submitted to the Engineer in accordance with site condition.

Not until the approval of the Engineer, the works of protection are not executed.

Where there are no suitable topsoil at the sections of washout embankment, the topsoil suitable for growing with a thickness of 10 cm is spread and compacted by hand in approval of the Engineer, 4 cm thickness of which is wetted if moisture is not enough.

Sods used for planting are obtained from the nearby place as per the consultant approval.

The size and space between each other of sods are in accordance with the drawing, which are watering regularly to ensure the survival ratio.