Examination Category(Civil Engineering)
Textbook for
the Practical Examination

Ver.20220908

Chapter 5: Knowledge of Tools, Machines, Materials, and Measuring Instruments Used on
Construction Sites
5.1 Tools, Machines, Materials, and Measuring Instruments Specific to Job Categories . 108
5.1.1 Construction Machines .................................................................................... 108
5.1.2 The Pipe-Jacking Tunneling Method ............................................................... 111
5.1.3 Marine Civil Engineering Work ....................................................................... 113
5.1.4 Well Drilling Work ........................................................................................... 115
5.1.5 Wellpointing Work ........................................................................................... 115
5.1.6 Paving Work ..................................................................................................... 116
5.1.7 Piling Work ...................................................................................................... 116
5.1.8 Scaffolding Work ............................................................................................. 117
5.1.9 Steel Framing Work ......................................................................................... 121
5.1.10 Steel Reinforcement Work (Rebar Work) ...................................................... 122
5.1.11 Rebar Splicing Work ...................................................................................... 124
5.1.12 Welding Work ................................................................................................ 125
5.1.13 Formwork Carpentry ...................................................................................... 127
5.1.14 Concrete Pumping Work ................................................................................ 129
5.1.15 Painting Work ................................................................................................ 131
5.1.16 Landscaping Work ......................................................................................... 134
5.2 Common Tools, Machines, Materials, and Measuring Instruments ............................ 136
5.2.1 Power Tools...................................................................................................... 136
5.2.2 Digging/Leveling/Compacting......................................................................... 139
5.2.3 Layout Marking/Marking Tools ....................................................................... 140
5.2.4 Measuring/Inspecting ....................................................................................... 141
5.2.5 Cutting/Bending/Breaking ............................................................................... 144
5.2.6 Tapping/Pulling ................................................................................................ 145
5.2.7 Filing/Polishing/Boring.................................................................................... 146
5.2.8 Tightening/Fixing............................................................................................. 146

5.2.9 Kneading/Mixing ............................................................................................. 148
5.2.10 Curing/Prepping ............................................................................................. 149
5.2.11 Scrubbing ....................................................................................................... 149
5.2.12 Carrying Objects ............................................................................................ 150
5.2.13 Hanging/Lifting/Pulling ................................................................................. 151
5.2.14 Work Platforms/Ladders ................................................................................ 152
5.2.15 Cleaning ......................................................................................................... 153

Chapter 6: Knowledge on Construction Site Work
6.1 Matters Common to Construction Sites ...................................................................... 155
6.1.1 Characteristics of Construction Work .............................................................. 155
6.1.2 Construction Plan ............................................................................................. 156
6.1.3 Construction Management ............................................................................... 156
6.1.4 Pre-Construction Preparations ......................................................................... 157
6.1.5 Layout Marking (Marking Out) ....................................................................... 159
6.2 Construction Knowledge of Each Specialty Work ...................................................... 160
6.2.1 Earthwork......................................................................................................... 160
6.2.2 The Pipe-Jacking Tunneling Method ............................................................... 162
6.2.3 Marine Civil Engineering Work ....................................................................... 163
6.2.4 Well Drilling Work ........................................................................................... 166
6.2.5 Wellpointing Work ........................................................................................... 168
6.2.6 Paving Work ..................................................................................................... 169
6.2.7 Mechanical Earthwork ..................................................................................... 170
6.2.8 Piling Work ...................................................................................................... 171
6.2.9 Scaffolding Work ............................................................................................. 173
6.2.10 Steel Framing Work ....................................................................................... 174
6.2.11 Steel Reinforcement Work (Rebar Work)....................................................... 176
6.2.12 Rebar Splicing Work ...................................................................................... 179

6.2.13 Welding Work ................................................................................................ 181
6.2.14 Formwork Carpentry ...................................................................................... 181
6.2.15 Concrete Pumping Work ................................................................................ 183
6.2.16 Painting Work ................................................................................................ 184
6.2.17 Landscaping Work ......................................................................................... 185
6.2.18 Demolition Work............................................................................................ 186

Chapter 7: Safety during Construction Work
7.1 Fatalities in Construction Work .................................................................................. 189
7 .1 .1 Numbers of Fatalities in Construction ........................................................... 190
7.1.2 Types of Fatal Accidents .................................................................................. 191
7.1.3 Work with A High Number of Fatalities .......................................................... 193
7.2 Safety Activities at Construction Sites ........................................................................ 196
7.2.1 Cycle of Safety in Construction ....................................................................... 196
7.2.2 Safety and Health Education for Newcomers .................................................. 198
7.2.3 Newcomer Education ....................................................................................... 199
7.2.4 Safety Gear for Work ....................................................................................... 200
7.2.5 Prevention of Heat Strokes .............................................................................. 202
7.2.6 Marks Calling Attention to Work Safety .......................................................... 202
7.2.7 Understanding Human Error ............................................................................ 203

Chapter 5: Knowledge of Tools, Machines, Materials, and Measuring
Instruments Used on Construction Sites
5.1 Tools, machines, materials, and measuring instruments specific to job categories
5.1.1 Construction Machines[Yuatsu shovel] (hydraulic excavator (backhoe)) A machine that

Hydraulic excavator

performs digging and loading work using the boom, arm, and bucket,
which are operated by hydraulic cylinders, and by rotating the upper
unit. By changing attachments, it can be used in various ways as abreaker, a ripper, a crusher, etc.
[Power shovel] A type of hydraulic excavators. A bucket is attached to the end of the arm. The bucket
is mounted with the opening upward. Suitable for excavating at a level higher than the machine's
position.
[Bulldozer] A machine consisting of a crawler (a metal or rubber belt)
type traveling unit equipped with a movable blade (dozer), mainly used
for excavation and transportation. There is also a machine calledrippable (bulldozer ripper) with a ripper that rakes up earth and rock.
[Ten’atsuki] (compactor) A machine that compacts by weight. There
are several types, depending on the material and shape of rollers andtheir combination.
[Road roller] A compactor with steel rollers. It is used to compact
subgrade layers and aggregate base layers in pavement construction.

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Bulldozer

Compactor

[Tire roller] A compactor with rubber rollers. It is suitable for ordinary
soil that is easy to compact and for crushed stones for aggregate baselayers of pavements. It is also used for machine-compacting asphalt
Tire roller

mixtures.
[Shindo roller] (vibratory roller) A compactor with vibrating steel
rollers. The vibration is normally vertical, but those that vibrate
horizontally are specifically called shindo roller (vibratory rollers).

Vibratory roller

Vibratory rollers have a strong compacting effect, even when they aresmall in size.
[Scraper] A machine that can single-handedly perform a series ofoperations such as digging, loading, transporting, and spreading soil.
The cutting edge at the bottom of the bowl, which fills with soil as it
travels, cuts the soil and places the excavated soil into the bowl. Upon
arrival at the embankment, the apron is opened, the soil is discharged,

Scraper

and the machine spreads it to a thin layer.
[Motor scraper] Self-propelled scraper. It cuts and levels the ground by scraping soil and sand using
the blade between the front and rear wheels, and sends the soil to a container above the blade.
[Motor grader] A machine used to flatten and finish the ground surface or aggregate base layermaterials such as paving stones. A scarifier and a blade
are located between the front and rear tires. The groundis torn up with a scarifier and the ground surface isleveled and compacted with a blade.

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Motor grader[Tractor shovel] (tractor excavator) A machine with abucket attached to the front of the tractor. Earth and sandcan be scooped up and loaded onto dump trucks using
the bucket. In addition to buckets for excavating earth
and rocks, the truck can be equipped with a fork forWheel-type tractor excavators and dump trucks

moving obstructing vehicles, etc., and a water gun for
firefighting. There are two types of models: the wheel type and the crawler type.
[Wheel loader] A loading and carrying machine that run on wheels, with a large bucket in front of the
body. By moving the vehicle forward and operating the bucket and boom,
the machine scoops up various materials such as earth, sand, and quarrystones and loads them onto dump trucks or other vehicles. A wheel loader
is a tractor excavator that runs on wheels, also called a tire dozer or tire

Wheel loader

excavator.
[Dump truck] A vehicle used exclusively for transporting earth,Dump trucksand, rocks, etc., and is capable of unloading soil (dumping) by tilting
the bed of the truck. Often used in combination with hydraulicexcavators and wheel loaders.
[Sakuganki] (rock drill) A machine used to break up hard rock and bedrock. It is used to drill blastingholes for dynamite and for drilling holes to insert wedges break rocks.
[Crane] A machine that uses power to lift and transport a load horizontally. There are several types of
cranes, including tower cranes, truck cranes, and crawler cranes.
[Rough-ter crane] (rough terrain crane) A type of construction machine with a crane mounted on atruck.
[Crawler crane] A crawler-type crane. It can work in a variety of locations, including on snow andunpaved ground.
110Rough terrain crane

Crawler crane

5.1.2 The Pipe-Jacking Tunneling Method
Pipe-Jacking Method Overview Chart(12) Crane equipment
Jacking pipe(11) Supply
facility (lubricant,backfill material)

RailroadRiver

Tunneling machine
receiving platform(15)(3) Launch portal
Tunnelingmachine (1)Intermediate jacking
station (10)Thrustring (4)Strut (5)Main thrusting jack (6)Reaction wall (8)(2) Jacking
pipe(14) Receiving
shaft(9) Jacking
base(13) Launching
shaft

Thrust block (7)[(1) Kusshinki] (tunneling machine) A machine that digs soil. There are various types of machines,
depending on the type of soil to be dug and the method of transporting the excavated soil.
[(2) Jacking pipe] Pipes used in the pipe-jacking method.
[(3) Hasshin koguchi] (launch portal) The opening where the jacking pipe is pushed out of thelaunching shaft and into the ground. The launch portal prevents leakage of groundwater and lubricant.
[(4) Oshiwa] (thrust ring) The thrust ring prevents breakage of the jacking pipe by evenly
transmitting the force of the main thrusting jack to the jacking pipes.
[(5) Strut] Struts are used to assist the lack of stroke of hydraulic jacks and as auxiliary struts to111

transmit the jacking force.
[(6) Moto’oshi yuatsu jack] (main thrusting hydraulic jack) The hydraulic force of the thrusting
hydraulic jack pushes the tunneling machine and jacking pipes into the ground.
[(7) Oshikaku] (thrust block) The thrust block distributes the reaction force of the jack and transfers
it to the support wall.
[(8) Shiatsuheki] (reaction wall) The reaction wall evenly transmits and supports the reaction forceof the main thrusting jack to the ground behind the jack.
[(9) Suishindai] (thrust frame) A thrust frame is a frame used to guide jacking pipes to a specified
height and direction.
[(10) Nakaoshi setsubi] (intermediate jacking station) The intermediate jacking station places ahydraulic jack in the middle of the tunnel to compensate for the lack of jacking force of the main
thrusting jack.
[(11) Chunyu setsubi] (supply facility) This facility supplies materials (e.g., lubricant and backfill
material) necessary for jacking.
[(12) Crane setsubi] (crane facility) This facility lifts jacking pipes and other objects and moves themdown the shaft.
[(13) Hasshin tateko] (launching shaft) A shaft used to push the tunneling machine and jacking pipes
into the ground. In the launching shaft, equipment such as the main thrusting jack is installed and thejacking pipes are connected.
[(14) Totatsu tateko] (receiving shaft) A shaft used to remove equipment such as tunneling machines
after the tunnel is completed.
[(15) Kusshinki ukedai] (tunneling machine receiving platform) This platform is used to push out
and retrieve the excavator after it arrives to the destination.

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5.1.3 Marine Civil Engineering Work
[Grab shunsetsusen] (grab dredger) A work vessel that grasps sediment from the seafloor bylowering a machine called a grab bucket, which is attached to a crane at the end of the vessel.
[Pump shunsetsusen] (pump dredger) A work vessel that lowers a rotating machine called a cutter
head, which is attached to the end of the vessel, to the seabed and digs the seabed while sucking up
both the dug sand and soil and sea water.
[Kijukisen] (crane vessel) A work vessel with a crane that lifts, carries, and installs heavy structures
such as large blocks and caissons.
Crane vessel

Pump dredger[Concrete mixer sen] (concrete mixing vessel) A work vessel equipped with machines for mixing
concrete materials and pumps for placing the mixed concrete.
[Gattosen] (carrier with grab) A work vessel with a grab bucket for transporting sand and stonematerials. It is self-propelled, so it can carry sand and stones to the site, use the vessel's grab bucket tograb the sand and stones and move them or throw them in.
[Dounsen] (sand/gravel carrier) A work vessel used to transport dredged earth and sand or stones
for construction materials. Some of them can open the bottom of the boat.
[Hikifune] (tugboat) A work vessel used to move large work vessels that cannot move by themselves
by pulling them with wires and ropes.

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[Yobyosen] (anchor handling vessel) A work vessel thatuses a winch attached to the top of the vessel to hoist theanchors of other work vessels or throw them into the sea.
[Ikari] (anchor) A weight placed on the seabed to secure

Anchor handlingvesselthe ship's position. It has claws, which are inserted into theseafloor to hold the ship in position.

[Sonar] A machine used to measure the shape of the seafloor, which cannot be seen directly.
[Reddo] (sounding line) A measuring tool with a weight at the end of a graduated rope, it is throwninto the sea to easily measure the depth of the sea by reading the marks on the rope.
[Fuhyo] (buoy) Equipment placed around construction sites
to notify non-construction vessels of the construction site.
Some of them glow at night.
[Koyaita] (steel sheet piles) Made of thin sheets of iron.
Both sides of a single steel sheet pile have hooks called

Buoy

interlocks that connect the steel sheet piles to each other.
They are interlocked to form a wall that keeps the soil from crumbling.
[Kokankui] (steel tube pile) A pile in the shape of a tube
made of rounded thin plates of iron. Steel tube piles come ina variety of sizes, ranging from 40-50 cm to over 1 m indiameter.

Wave-dissipating
blocks[Concrete block] Making, installing and assembling small
concrete blocks can create a wave-resistant structure.
Concrete blocks of various shapes are used in marine
engineering works.
[Caisson] A large box made of concrete used to build
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Caissonbreakwaters, quays, and other marine structures. Larger ones are more than 20 meters in length, width,and height.
[Suteishi] (uniform riprap) Stones of the same size (30~1,000 kg) and strength for construction.
They are piled to create a trapezoid-shape site (foundation mound) on which structures are built.

5.1. 4 Well Drilling Work
[Boring machine] (drilling machine) Machines for digging relatively small-diameter holes in the
ground. It is used to dig wells as well as for geological surveys. Excavation is performed by rotational
and percussive forces. There are rotary drilling machines, percussion drilling machines, rotary
percussion drilling machines, etc.
[Bit] A component used in the rotary koho (rotary drilling method) Rotating the bit allows digging
through the ground.
[Air hammer] A component used in the air-hammer method. Attached to the end of the drill shaft, it
digs through the ground by rotational and percussive forces. There is a hole at the end of the hammer,
and air pressure delivered through the drill shaft can blow the dug soil up to above the ground.
[Boring pump] A pump used to pump up groundwater from the boreholes. It is used in combination
with boring machines.

5.1.5 Wellpointing[Wellpoint] A collection pipe fitted with a mesh for filtration. It is attached to the end of a water supply
pipe called a riser pipe.
[Casing kan] (casing pipe) The outer pipe in a double-pipe wellpoint, with the riser pipe inside. A
vacuum pump is used to create a vacuum inside the casing pipe to forcefully collect pore water aroundthe well.
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[Rotary percussion drill] A machine that drills holes in the ground by rotation and percussion. In thewellpointing method, it is used to drill holes for large-diameter wellpoints.
[Water jet] A pump used to create a jet of water to drive riser pipes into the ground. A high-pressure
jet of water from a nozzle at the tip is used to drill a hole through which the riser pipe is driven.

5.1. 6 Paving Work
[Asphalt] Material used in paving. It is made from the residue left over from producing gasoline ordiesel oil. It hardens at room temperature and becomes liquid at higher temperatures.
[Asphalt finisher] A machine used to spread and level asphalt. It consists of a tractor section withengine, hopper, and screed. There are two types of tractor sections: crawler type and wheel type. A
hopper is a cage-like device that holds asphalt. Screed is a device for spreading asphalt. Asphalt fromthe hopper is sent to the screed by a conveyor belt.
[Concrete cutter] A machine for cutting concrete and asphalt.
[Breaker] (paving breaker) A machine used to break the road surface of paved roads. It is used byattaching it to the tip of a hydraulic excavator or backhoe. It is also used for demolition of concrete
structures and rock excavation.
[Distributor] A machine used to spread asphalt emulsifier on roads. A large tank is equipped withasphalt emulsifier, which is sprayed onto the asphalt

Hand guide roller

pavement from the back of the vehicle.
[Hand guide roller] A small hand-pushed road roller.

5.1.7 Piling Work
[Earth drill kussakuki] (earth drilling machine) A machine used in the cast-in-situ concrete piling
method that drills holes for piles. The ground is excavated by rotating the drilling bucket. Soil
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accumulates in the bucket and is discharged to the ground when full. This method is called the earth
drill method.
[Zenshukaiten kussakuki] (full slewing excavator) A machine used in the cast-in-situ concretepiling method that grasps a steel tube called a casing (or casing tube) and pushes it into the ground
while rotating it 360 degrees. This method is called the all-casing method.
[Hammer grab] This bucket is used to grab up earth and sand in the casing tube and discharge it to
the ground. Used in conjunction with a full slewing excavator in the all-casing method.
[Pile driver] A machine for drilling holes to set pre-cast piles. For large machines, there is a threepoint pile driver to support the drill section stably.

5.1. 8 Scaffolding Work
[Ashibayo buzai] (scaffolding members) Members used to build scaffolding. The materials used fortube scaffolding, frame scaffolding, and ringlock scaffolding differ from each other.
[Kusabi kinketsushiki ashibayo buzai] (ringlock scaffolding members) Kusabi kinketsushiki
ashiba (ringlock scaffolding) is a type of scaffolding that uses scaffold members designed to beassembled and disassembled with a single hammer. Basic members include jacks, posts, handrails,
scaffold planks with hooks, brackets, cross braces, steel stairs, guardrails, and wall jacks. Basicmembers are galvanized to resist rust and provide durability.
[Wakugumi ashibayo buzai] (frame scaffold members) Wakugumi ashiba (frame scaffold) is a typeof scaffolding in which basic members such as jacks, cross braces, and steel scaffold planks with hooks
are assembled around portal frames. Basic members include formwork, jacks, cross braces, joint pins,
scaffold planks, wall tie anchors, handrails, ledgers, and toe boards.

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[Tankan ashibayo buzai] (tube scaffolding members) Tankan ashiba (tube scaffolding) is a type ofscaffolding that is assembled using clamps to bind circular hollow sections made of 48.6 mm-diameter
steel tubes. The scaffold shape can be flexibly changed, allowing it to be used for scaffolding in tightspaces. It is inferior to frame scaffolding in terms of strength and safety, and is mainly used as
scaffolding for painting low-rise exterior walls. Basic members include circular hollow sections, footplates, clamps, circular hollow section brackets, scaffold boards, and joints.
Frame
scaffoldingTubescaffolding

Ringlock scaffolding[Tankan pipe] (circular hollow section) Tubes for scaffolding made of 48.6 mm-diameter steel tubes.
[Joint] A member used to connect circular hollow sections.
[Kotei base] (foot plate) Base fitting to fix an upright circular hollow section (tateji (upright circularhollow section)).
[Clamp] Hardware used to connect circular hollow sections orthogonally or diagonally. There are 90degree clamps and adjustable clamps.
[Sujikai] (cross brace) A member used to reinforce the structure in order to prevent scaffolding fromcollapsing due to wind or other factors. It is placed diagonally between the posts.

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[Ashibaita] (scaffold board) Boards that serve as working aisles and platforms in scaffolding.

Clamp

Cross
brace
Clamp

Circular hollow
CircularhollowsectionsectionFoot plate

ScaffoldboardFoot plate[Nunoita] (scaffold plank with hooks) A member that

Scaffold plankwith hooks

serves as the working platform of scaffolding. Unlike
scaffold boards, it has hooks to secure it to the beams
attached to the upright circular hollow section.
[Tankan bracket] (circular hollow section bracket)
A member used to support the scaffold board from below. The horizontal portion onto which thescaffold plank with hooks is supported at an angle.
[Habaki] (toe board) Board material attached to theouter edge of the scaffold board. Attached to prevent
objects from falling.

Circular hollow
section bracket[Kabetsunagi] (wall tie anchor) A member to securescaffolds to walls and other structures to prevent them from collapsing.
[Bo’on panel] (soundproofing panel) A panel attached
to scaffolding for soundproofing. Aluminum or stainlesssteel products also serve to prevent the spread of fire.
[Bo’on sheet] (soundproofing sheet] A sheet put up on
scaffolding for soundproofing.
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Toe board[Anzen block] (safety block) A device used to prevent scaffold
workers from falling from heights. The hook of the safety block ishooked to the safety belt.
[Bansen] (thick wire) The thick wire used to assemble scaffolding
Safety blockis called bansen. To make it stronger than ordinary wire, the iron istreated with heat and then allowed to cool slowly.
[Bansen cutter] (thick wire cutter) A tool used to cut thick wire.

Thick wire cutter

Thick wire

[Chino] A curved tool with a pointed tip. It is used for tying and tightening of thick wires.
[Chino tsuki ryoguchi ratchet wrench] (double-ended ratchet wrench with chino) One end of thegrip is pointed, allowing tightening of thick wires, etc. The pointed end is called shino (chino). The
other end with a hole allows tightening and loosening of bolts. It is used in scaffolding and rebar
construction. The size mainly used by steeplejacks is 17 x 21 mm.

Chino

Ratchet wrench with chino[Ratchet wrench] A wrench that incorporates a120

clutch that fixes the direction of rotation in one direction(called ratchet kiko (ratchet mechanism)). The ratchetmechanism allows efficient turning of bolts and nuts withjust a reciprocating motion of the lever. In steel framing
work, a ratchet wrench with a chino, or a pointed form,

Ratchet wrench with chinoon one end, is used.

5.1.9 Steel Framing Work
[Borushin] (drift pin) A tool used to align bolt holes in steel section joints by tapping into the bolt
holes when they are misaligned.
[Wrench, spanner] A tool used to tighten and loosen bolts
and nuts by rotating them. In American English, it is called
wrench, and in British English, spanner. They both mean thesame thing in English, but in Japan, they refer to different

Spannertools. The wrench has a hexagonal tip and captures the bolt at
six points, while the spanner has an open tip and captures the bolt at two points.
[Megane wrench] (box wrench) A wrench with ends of different diameters on both sides of the grip.
[Combination wrench] A wrench that has an opening and captures and turns bolts and nuts at two
points. A combination wrench is a wrench with one spanner end and one box wrench end. The end isangled at 15 degrees to the grip, so the back and front sides can be used alternately to provide a rotating
stroke for efficient work.
[Impact wrench] A power tool for turning and tightening hexagonal bolts using the impact from thebuilt-in hammer.

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5.1.10 Steel Reinforcement Work (Rebar Work)[Tekkin cutter] (rebar cutter) A tool used to cut reinforcing
steel bars. There are four types: manual, manual hydraulic,electric hydraulic, and electric circular saw with a tipped
blade.

Electric rebar cutter[Dendo tekkin cutter] (electric rebar cutter) A power toolthat uses a hydraulic pump to move the blade and cut therebar. The rebar is grasped with the tip, and cut by pressing
the blade against it.

Rebar bender[Dendo yuatsushiki tekkin cutter] (electric hydraulicrebar cutter) A portable cutting machine that can cut rebar
using electricity and hydraulic pressure.
[Tekkin bender] (rebar bender) A tool used to bend rebar.
[Dendo yuatsushiki tekkin mageki] (electric hydraulicStationary rebar benderrebar bender) A portable bender that can bend rebar using
electricity and hydraulic pressure.
[Teichishiki tekkin mageki] (stationary rebar bender)
Stationary-type rebar bender mainly used in rebar processing
plants.
Rebar tier

[Tekkin kessokuki] (rebar tier) A power tool for tying rebars.
Simply insert the arm into where the rebars cross, and pull the trigger to tie them.
[Spacer] A member to secure space (space between the rebar and the formwork) of the rebar. Spacers
for the sides are called donuts, and the members that hold the top and bottom of the slab or beam arecalled bar supports.

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[Donut] Donut-shaped spacers fitted to rebars in columns, beams,
and walls to secure space for the correct concrete cover thickness.
[Caramel] Dice-shaped mortar blocks placed under the floor
reinforcement to secure the concrete cover thickness of the floor

Donutsreinforcement.

Caramel[Pura cap] (plastic cap)
Plastic caps placed conspicuously over the tops of the vertical joint
bars and the edges of horizontal bars after completion of the rebar
Plastic cap

placement as a safety measure to prevent injury.

[Orijaku] (folding ruler) A tool for measuring short lengths. It ismainly made of fiberglass or wooden material and has an extended
length of one meter. It is useful when working alone or in situations
where it is difficult to work because it can be folded. This tool isoften used in rebar work.
Folding ruler[Kessokusen] (binding wire) A mild steel wire (generally No. 21
in thickness) used to connect rebars.
Binding wire

[Hacker] The tying and fixing of reinforcing steel bars together iscalled tekkin no kessoku. The tool used to twist and tighten thebinding wire used for tying rebars is called a hacker. It is the mostimportant tool for a rebar worker. There is a hacker case to store
the hacker.
Hacker123

[Nifuda/efu] (tag) A tag indicating the size, use, position ofuse, and number of rebar brought in to the site. It is tied to
the rebar using a thin wire.

5.1.11 Rebar Splicing Work
Ram cylinder[Kaatsuki] (pressure system) The section consisting of ahydraulic power unit, a high-pressure hose, and a ram cylinder,
which generates the hydraulic pressure necessary for pressure

Welding
fixturewelding.
[Assetsuki] (welding fixture) The section in which two rebars to be pressure-welded are set. It isdriven by hydraulic pressure generated by a pressurizing pump.
[Ram cylinder] A device used to transfer the hydraulic pressure to
the pressure system.
[Koatsu hose] (high-pressure hose) A hose with a flexible bendable
structure that can withstand high pressure.
[Dendoshiki kaatsusochi] (electric pressurizer) A hydraulic pumpthat can set the pressurizing power as desired. Pressurization can be

Electric pressurizer

turned on and off with a switch at hand.
[Jido kaatsusochi] (automatic pressurizer) A machine in which pressurization sequences areprogrammed to automate pressurization.
[Burner] (welding torch) The section that emits flames toheat the pressure-weld joint. There are several different
shapes.
Burner124

[Suikan] (blowpipe) A heating apparatus for mixing andBlowpipedelivering oxygen and acetylene gas.
[Eco-valve] A valve designed to open and close the oxygen andEco-valvethe acetylene gas flow at the same time. It is used by attaching
it to a blowpipe.
[Gaikan sokuteiyo kigu] (welding gauge) An inspection tool
to measure the diameter and width of the bulge of the pressureweld joint.
[Cho’onpa tanshoki] (ultrasonic flaw detector) An
inspection device that detects internal defects by applying

Welding gauge

ultrasonic waves to the pressure-weld joint.
[Hippari shikenki] (tensile tester) A machine that performs
tensile tests, which pulls pressure-welded rebars, to test the strength.
[Mage shikenki] (bend tester) A machine that performs bend tests totest the strength of pressure-welded rebars.
[PS ring] A high molecular weight reducing agent to prevent oxidationof pressure-weld joints. It also makes it less susceptible to wind and rain.

PS ring

5.1.12 Welding Work
[Hifuku arc yosetsuki] (shielded arc welding machine) A
welding machine that uses a welding rod with a metal core
covered with a coating material (called “flux”). This type of
welding machine is often used at work sites. Welding with ashielded arc welding machine is sometimes called teyosetsu

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Shielded arc welding
machine(manual welding) because it is done entirely by hand.
[Yosetsubo] (welding rod) Metal rods used to bond thebase metal to be welded. In arc and gas welding, it melts
Welding rod

and becomes one with the base metal.
[Yattoko] (pliers) A tool made of iron for gripping heated iron andother materials. It consists of two metal rods connected by a hinge.
They can be used to grasp objects with strong force using the principleof leverage. They are also used in welding to bend things.
[Sekihitsu] (stone scribe) A tool used to draw kegaki (scribe marks)

Plierson iron plates, etc. for welding and torch-cutting. Kegaki (scribe marks) means to scratch and drawlines on the material.
[Spatter fuchaku boshizai] (anti-spatter compound) Spatter is the slag and metal particles scatteredduring welding. Since they can lower the quality of the weld finish, this compound is used to preventthe spatter from sticking. The compound is applied to thematerial before welding by brush or spray.
[Shield-mentsuki helmet] (welding helmet) A helmet with ashield attached to it, protecting the entire face. Mainly used forHelmet with a face shieldwelding work.

126

5.1.13 Formwork Carpentry[Form tie] A tool attached to separators to keep the formwork spacing constant, improve passage, andprevent deformation of the formwork due to lateral
Form tiepressure from the concrete. It is used to bind thetubes.
[Maru separator] (round separator) A tool

Concrete wall

Round separator
P-con

commonly called sepa or marusepa that is placed
between formwork facing each other to ensure thatFormwork plywood

Circular hollow
sectionthe thickness of the concrete will be as indicated in
the construction drawings.
[P-con] A plastic part that is attached to an end of a separator. Attached to both ends of the separator,
they hold the formwork panel in place.
[Tankan pipe/kokan pipe] (circular hollow section, steeltube) A material used to increase the strength of the

Circular hollow
sectionformwork. Circular hollow sections are round whereas steel
tubes are square-shaped.

Form tie[Sangi] (batten) A 25 x 50 mm piece of wood used together
with plywood. It is used at joints between panels and to supplement the strength of the formwork.
[Sekiita] (formwork plywood) Plywood used to make formwork. Generally, 12 mm thick conpane(formwork plywood) is used.
[Panel katawaku] (panel formwork) A panel-shaped
formwork made by nailing pieces of batten onto plywood
to create a panel. Panel formwork is intended for repeatedPanelformwork

use.
[Batakaku] (floor support timber) Square timber with a width of 90 mm or 105 mm. It is used to127construct pipe supports for receiving the circular hollow sections for the floor framework. It is also
used as a platform on which to place heavy objects.
[Pipe support] (tube support) A member used for the bottom plate of beams and as supports for floor
formwork. It bears the compressive forces. It is called sapo, sappo, support, etc. for short.
[Tonbo bata] (square timber) Square timber often referred to as tonbo and used to construct tube
supports for receiving the circular hollow section (called neda pipe (joist tube)) for the beam bottom
formwork.

Beam bottom
formwork

Floor support
timberTube support

Tube support

Beam support
timber[Kakikomizai] (grooving material) A material attached to the formwork to make grooves in concrete
for window frames, etc. It is commonly referred to as ankozai.
[Mengi] (cornering material) Material used to create corners with concrete.
[Mejibo] (grooving rods) Material used to make grooves in the flat surface of concrete.
[Turnbuckle/chain] Used to prevent collapsing of the formwork and to adjust the verticality (i.e., toaccurately level and straighten the columns and beams) by pulling.
[Separator hook] A tool used to guide the separator into the hole drilled in the formwork.
Chain

Turnbuckle

Separator hook128

[Form tie mawashi] (form tie spanner) A tool used for tightening and loosening form ties.
[Kariwaku hammer] (formwork hammer) This hammer is used to make the formwork for pouringconcrete. It can also pull out nails.
Formwork hammer

Form tie spanner[Hakurizai] (release agent) An agent applied to the surface of the formwork to facilitate removal.

5.1.14 Concrete Pumping Work
[Agitator] A device that agitates pre-mixed concrete to prevent it from hardening. Trucks equippedwith this function are called truck agitator (concrete agitator trucks) or nama-consha (ready-mixed
concrete trucks).
[Concrete pump] A machine that uses hydraulic or mechanical pressure to feed ready-mixed concrete(concrete made at a factory that has not hardened yet) brought in by concrete agitator trucks into theformwork. There are two types of pumps: piston shiki (piston type), which has high pressure and canpump over long distances, and squeeze shiki (squeeze type), which has low pressure and limited
pumping distance. A device in which a concrete pump is mounted on a vehicle is called a concrete
pump truck.
[Hopper] (concrete hopper) A part that receives ready-mixed concrete from a concrete agitator truck.
A screen is attached to the concrete hopper to prevent people and foreign objects from falling into thehopper.
[Level sensor sochi] (level sensor device] A device that detects the amount of concrete in the hopper

129and automatically operates and stops the machine.
[Kinkyu teishi sochi( (emergency stop device) A device used to stop the movement of the concrete
pump when a person is about to be or is caught in the agitator.
[Agitator jido teishi sochi] (automatic agitator stop device) A device that automatically stops the
movement of the agitator when the hopper screen is opened.
[Doryoku dentatsu sochi (PTO)] (Power Take-Off (PTO)) A device used to take the power fromthe engine needed by various parts of the concrete pump. Engine power is transmitted to drive theconcrete pump truck, operate the outriggers and boom, and power the hydraulic generator.
[Yuatsu kairo] (hydraulic circuit) A device that generates the hydraulic pressure to move theequipment of the concrete pump truck. The hydraulic circuit consists of a hydraulic power unit, ahydraulic control unit, a hydraulic actuation system, and other ancillary equipment.
[Jido kyuyu sochi] (automatic lubricator) A device that sends grease from a grease pump to thebearings of concrete cylinders, S-pipes, and agitators.
[Senjo sochi] (washer) A device used to wash concrete left in various parts of the equipment of
concrete pump trucks after pumping operation.
[Boom sochi] (boom) Equipment used to bring the delivery pipe to the location where the concrete is
to be placed. Booms can be folding, telescopic, or a combination of these types.
[Senkai sochi] (boom manipulator) A device that moves the boom up and down and swivels it.
[Kadai sochi] (superstructure) A structure for attaching boom and outrigger devices to the vehicle
body. It consists of a sub-frame and a boom pedestal.
[Outrigger sochi] (outrigger) A device that extends outward from the body of the vehicle to maintainthe stability of the concrete pump truck.
[Yusokan] (delivery pipe) A pipe used to deliver concrete from the concrete pump truck to thelocation where the concrete is to be placed. It consists of straight pipes, elbow pipes, tapered pipes, aplacing hose, etc.
130

[Cement] Material used to make concrete. It has the property to harden when mixed with water.
[Kotsuzai] (aggregate) Sand or gravel that is mixed with cement when making concrete or mortar.
[Konwazai] (mixing agent) Anything other than cement, water, sand, and gravel that is added toconcrete to improve its performance. Includes damping agent, superplasticizer, and hardening
accelerator.
[Slump cone] A formwork for conducting a slump shiken (slump test) to check the quality of readymixed concrete. After pouring the ready-mixed concrete into the slump cone, the slump cone isremoved in order to check the change in height of the ready-mixed concrete. A slump test is always
performed prior to placing concrete.

5.2.15 Painting Work[Hake] (brush) A tool for painting with bristles attached to the end of a wooden or plastic handle.
There are various types of brushes, including bristle brush,Brushrubber brush and flat brush, depending on the area to be painted
and the type of paint, such as oil-based or water-based.
[Pate] (putty) A paste-like material used to eliminate
unevenness and flatten the surface of a substrate (called pateshori (puttying)).
[Spatula] This tool can be used to mix, apply, and scrape off paint.
[Jushibera] (resin spatula) Used for mixing putty, filling putty,
spreading adhesives, and pressure bonding masking tapes. There aredifferent types depending on the hardness (bendability), and they areused for different purposes.
[Kanabera] (metal spatula) Used for various purposes such as

131

Resin spatulamixing putty, leveling and finishing, and pressing sealant.
[Joban] (mortar board) A thin board to be held with one hand on which mortar or putty is placed.
Mortar or putty is kneaded using a spatula on the mortar board.
[Teguwa] (plasterer hoe) A tool used to mix wall materials and carry them to the place where they
are to be painted. It is sized so that it can be held and operated with one hand.
[Wool roller] A roller used for efficient painting of wide

Wool roller

surfaces. Used in combination with roller handles. Longer
bristles allow the paint to soak in better and are suitable forpainting large surfaces. The shorter ones leave less hair trails
and create a cleaner finish. There are also polyurethane rollers
which can be used for water-based and solvent-based paints.
[Scraper] A tool used to remove stuck-on paint and dirt. The

Blade of a scraper

process of scraping off rust and other debris from surfaces
before painting is called keren sagyo (scraping work), and ascraper is used in this process. Larger ones, also called kerenbo(scraping sticks), are used not only for the scraping work but
Skiving knife

also for removing P-tiles from the floor.
[Kawasuki] (skiving knife) The tool was originally used toskive skins, but because of its sharp blade, it is also used for
keren sagyo (scraping work) in the painting process.
[Spray gun] A painting tool that uses compressed air from a compressor to spray a fine mist of paint.
Depending on the paint supply method, there are gravity, suction, and pressure-feeding types.
[Masking tape] A tape used to protect certain areas from paint. It is applied to the border between thepainted area and the area to be protected. It can be easily peeled off. To prevent paint from seeping inthrough the gaps, press the tape down well with finger so that there are no lifted areas.
132

[Masker] (masker tape) Adhesive tape with a folded sheet to easily protect a large area. The tape isapplied to the protective surface first, and then the sheet is unfolded. Non-slip type is also available.
[Tape primer] A primer used for areas where masking tape is difficult to adhere, such as uneven areasof concrete. Spray-type products are often used.

Masking tapeProtective tape

Masker tape

Tape primer

133

5.2.16 Landscaping Work
Tools used in landscaping work 1[Karikomi basami (1)] (trimming shears) Scissors used to cut the leaves and branches to shape thehedges and low garden trees.
[Sentei basami (2)] (anvil shears) Scissors for cutting thick branches.
[Kibasami (3)] (pruning shears) Scissors for cutting thin branches. They are also called uekibasami.
[Sentei nokogiri (4)] (pruning saw) A saw used to cut branches that are too thick to be cut withpruning shears.
[Chain saw (5)] A tool that cuts by rotating a chain with many blades. It is used for cutting tree trunks,
etc. There are electric and engine types.
[Hedge trimmer (6) (7)] A tool used for trimming. The two blades move in a scraping motion to cut
branches and leaves, just like scissors. There are electric and engine types.
[Karibaraiki (8)] (mower) A tool for cutting weeds.

134Tools used in landscaping work 2[Enpi (2)] (pointed spade) A shovel used to cut the lateral roots around the root of a tree.
[Konokiri (11)] (wooden mallet) A small mallet. It is made of hard wood such as oak or zelkova. It
is used to lightly drive support logs or other materials into the ground.
[Tsukibo (12)] (poke stick) A stick used to poke the soil when burying tree roots in a hole.
[Takewari (13)] (bamboo machete) This machete is specially designed for vertically splitting andshaving bamboo.
[Kuribari (16)] (needle for bamboo fences) A needle used to tie bamboo to bamboo with shuro nawa
(palm rope) when making bamboo fences. It is curved like a fishhook and is used by threading theshuro nawa through the hole.
[Pin hole (19)] Used to put up level lines by inserting them into the ground.
[Kogai ita (20)] (leveling board) A tool used to beat the soil, sand and prominent soil grains topartially level the ground. It is used to clean up the edges around stones, etc.

See separate sections for the following tools.
[Double sukoppu(1)] [Ken sukoppu (3)] [Makijaku (4)] [Drill (5)] [Bar (6)] [Kanazuchi (7)]135

[Suiheiki (8)] [Reki (9)] [Kakeya (10)] [Nokogiri (14)] [Mizuito (15)] [Renga gote (17)][Meji gote (18)]

5.2 Common Tools, Machines, Materials, and Measuring Instruments
5.2.1 Power Tools
Power tools can be cordless types that use rechargeable batteries or corded types that use AC power.
[Drill driver] This electric screwdriver can be used for screwing and drilling by changing the bits.
Rotation speed and torque can be adjusted.
[Impact driver] An electric screwdriver that can tighten screws using the impact from the built-in
hammer. It has more power than a drill driver. Rotates at a constant rotation speed and torque.

Drill driver

Impact driver[Bit] A part attached to the tip of an electric screwdriver. Various types of bits for drilling and screws
are available. The part where the bit is attached differs between a drill driver and an impact driver.

Drill driver

Impact driver[Disk grinder] (angle grinder) This power tool can cut, grind, and remove paint from metal pipes
136

and concrete by changing the disc (a round, flat grinding stone for grinding and cutting) attached tothe end of the tool. The high speed torque type is suitable for metal cutting, while the low speed torquetype is suitable for grinding.

Angle grinder

Disk[Sander] This power tool is used to polish flat surfaces by moving sandpaper. There are several typesof mechanisms for moving sandpaper, including vibrating, belt, and rotating types.
[Marunoko] (circular saw) A power tool for cutting plywood and other materials in a straight line.
Hand-held and fixed types are available. The hand-held type, when it touches the material to be cut,
may move in an unexpected direction due to a force (called kickback) that lifts it away from thematerial. This leads to many accidents, and in some cases, they can be serious, life-threatening
accidents. Before use, make sure that the safety cover is working properly.
[Marunoko guide jogi] (circular saw guide ruler) Attached to a circular saw, this ruler is used to cut
materials in a straight line.

Circular saw

Circular saw guide ruler[Shujin marunoko] (circular saw with dust collection) A circular saw that can cut while collecting
137

fine dust. Two types are available: one for board cutting and the other for metal cutting. There are two
types: one with a dust box to collect dust, and the other with a dust collector to be connected to thecircular saw.
[Shujinki] (dust collector) A power tool used to collect dust produced by cutting. It is used whencutting tile and concrete products to prevent cutting debris from flying out into the neighborhood.
[Kosoku setsudanki] (high-speed cutter) An electric toolthat cuts metal pipes, rebar, light steel sections, etc. byrotating a grinding stone for cutting. Much like a chip saw
cutter, but a chip saw uses a circular saw blade to cut
High-speed cuttermaterials. The blades of chip saw cutters wear easily,whereas the blades of high-speed cutters last longer.

[Recipro saw] (reciprocating saw) A power tool that cuts materials by moving a long, thin blade backand forth.
[Dendo block cutter] (electric block cutter) A power tool for cutting concrete.
[Kugiuchiki] (nail gun) A tool that uses the force of air pressure compressed by a compressor to drive
nails into materials. A compressor is a machine that compresses air.
[Denko drum] (cord reel) A tool for extending an outlet.

Cord reel

Nail gun1385.2.2 Digging/Leveling/Compacting[Ken sukoppu] (spear head spade) A tool used for digging in the ground by placing the foot on the
top of the head. It is also called kensuko for short. Do not use as teko (lever).
[Kaku sukoppu] (square head spade) A tool used to scoop and carry soil, asphalt, etc. It is similar
to a spear head spade, but the blade edge is straight to make it easier to scoop soil and other materials.
Also, the top is rounded and does not allow for foot placement. Do not use as teko (lever). It is also
called kakusuko for short.
[Double sukoppu] (double spade) These spades can poke through the ground to dig a deep hole. The
dug soil can be grabbed under the surface and pulled out. It is used for digging holes for piles andutility poles.

Spear head spade

Square head spadeDouble spade[Tsuruhashi] (pickaxe) A tool used for excavating hard ground and breaking up asphalt.
[Reki] (rake) A tool used to level soil, spread asphalt, and collect fallen leaves. There are various
shapes and materials, depending on the purpose. Rakes for leveling soil have many thin tines, but rakes
for asphalt have none.
[Joren] (dredge hoe) A tool used to rake up earth, sand and debris.
[Tako] (manual compactor) A tool used to beat and pack soil and other materials by weight.
[Tamper] A tool with a flat metal plate attached to the end of a long handle. It is used to compactasphalt and other materials by holding the handle and tamping the surface from above.

139

[Rammer] A machine used to compact the ground. The weight of theRammerrammer and the force of the impactor, which moves up and down,
compact the surface. It has strong striking power and is suitable forstrong compacting. There are engine- and electric-powered types.
[Vibro-compactor] A machine equipped with an engine to compact
soil and sand by its own weight and vibration. Used for compacting road aggregate base layers, roadsubgrade layers, backfill, etc. The machine is pushed and pulled back and forth by hand to compact
the surface. Although the impact force is inferior to that of a rammer, a large area can be compacted
at once. A similar machine is the plate compactor. A plate compactor is more suitable for flattening
due to the larger area of the compacting plate and smaller vibration.
[Vibrator] A machine used to remove air bubbles from concrete and increase the density of theconcrete during concrete placement through vibration.

5.2.3 Layout Marking/Marking Tools[Sumitsubo] (line marker) A tool used for marking longstraight lines on the surface of a material.
[Sumisashi] (ink pot) The flat part of the ink pot is used fordrawing lines, and the round part (ho) is used in the same way
as a brush.

140

Line marker

[Chalk line] Similar to the sumitsubo line marker, but draws a line with powdered chalk.
[Laser marker] A machine that emits laser beams onto walls, ceilings,
and floors to produce horizontal, vertical, and other reference lines forconstruction. Laser beams are available in red and green. Green isrelatively easier to see in bright locations. Protective goggles for laser
work are worn to prevent the laser beam from directly entering your eyes.

Laser marker[Marker pen, marking chalk] Oil-based pen for architectural use. For
example, it is used to allocate the position and pitch (distance between reinforcing bars) where thereinforcing bars are placed.
[Punch] This tool can be used to make small indentations in metal
surfaces by tapping with a hammer, or to make round holes in
Punch

cloth, leather, etc. The center punch is used to mark metal surfaces(this is called marking).

5.2.4 Measuring/Inspecting[Level] A leveling device used to determine the height necessary
for the work. Mounted on a tripod, the device is manually leveledby balancing the built-in bubble vial. A level with an automaticleveling mechanism is called an auto-level.
[Laser level] An instrument for level surveying by laser and isused to determine the height necessary for the work.

141

Level

[Transit] An instrument that measures the vertical andhorizontal angles based on the viewpoint supporting a small
telescope. It is used on a tripod. These days, a digital display
type of device called theodolite is often used.

Transit[Total station] A surveying instrument that combines a lightwave rangefinder and an electronic transit. Look through the telescope and simply align the crosshairs
with the target and press the button to simultaneously measure the distance and angle from thereference point. Total stations are used in a wide range of surveying applications, including
topographic surveying, construction site location management, initial ground surveying, and fixed
point surveying.
[Mizuito] (line level) Thread used to straighten lines and matchheights when building foundations or stacking bricks and blocks. It is
made of non-stretch material.
[Suiheiki] (level) A tool used to check whether a construction surface

Line levelor object is level with the ground. The level is checked by looking
at the air bubble in the vial. Some use the needle to check thelevel, and some are digital levels. Levels with a built-in
inclinometer are also used in residential installations.

Level[Sagefuri] (plumb bob) A weight with a pointed conical tip used
to check the verticality of a pillar or other objects. The verticality is checkedby hanging it from a plumb bob holder fixed to a post using a thread andchecking if the distance between the surface to which the holder is attachedand the thread is constant.

Plumb
bob

142

[Sashigane] (carpenter’s square) A tool made of stainless steel or other metal, used to measure rightangles. It is scaled and can also be used to measure length. The front side is in metric scale, and theback side is 1.414 (√2) times the front side.
[Ogane] (triangular ruler) A large triangular ruler for

Carpenter’s squaremeasuring right angles. It is made on site using the Pythagorean
theorem, the ratio of 3:4:5 . The 3:4:5 is called sashigo at theworksite.
[Measure] (tape measure) A tape-like tool for measuring length. Sometimes referred to as makijaku(tape measure). Available in steel and vinyl.

Convex[Convex] (retractable steel measuring tape) A measure with athin metal tape that measures length. Sometimes abbreviated asconbe, the official name is the convex rule.
[Jogi] (ruler) A tool used for measuring length and drawing
straight lines. Materials include aluminum, stainless steel, and bamboo. To avoid damaging materials
such as fittings, bamboo
rulers are used.
Aluminum ruler

Stainless steel ruler

Bamboo ruler[Slump kenjaku] (slump scale) An instrument used tomeasure the slump value (the lowered height after the slump
cone is removed) in the slump test.

A slump test being
conducted

1435.2.5 Cutting/Bending/Breaking[Nokogiri] (saw) A tool with many blades (called me (teeth)) on a metal plate, used to cut wood, metal,
pipes, etc. It is called noko for short.
[Hasami] (scissors) A tool used to cut objects between two blades.
[Kuikiri] (end nipper) A tool used to cut objects between theblades. Used for processing tiles, cutting wires, etc. It can also
cut the head of a nail.
[Cutter knife] (box cutter) This knife can maintain its sharpness

End nipper

by breaking off the tip of the blade.
[Tagane] (masonry chisel) A stick-shaped tool with a blade on one end that can be used to cut thinmetal by tapping it with a hammer. It is also used for hatsuri sagyo (breaking), to break concrete andmark measurements of roof tiles. Flat masonry chisel, concrete masonry chisel, carving masonry chisel
and others are available depending on use.
[Penchi] (pliers) A tool for bending, cutting, etc. There is a part for gripping with fine grooves toprevent slipping and a part with blades for cutting.

Box cutter

PliersMasonrychisel144

5.2.6 Tapping/Pulling[Hammer] A tool used to strike things. The material of thestriking head can be metal, rubber, or wood, depending on theintended use. Those with a metal head is sometimes called
Example of a hammer (for ringlock scaffolding)kanazuchi.
[Rubber hammer] A hammer with a rubber head. It is

Rubber hammer

characterized by its strong striking power without damaging thematerial. It is used to compact concrete by tapping the formwork
and making it vibrate during the concrete placing process.
[Kizuchi] (wooden hammer) A hammer with a head made ofWooden hammer

wood. Although the striking force is weaker than that of a metal
hammer, it is less likely to damage the material.
[Kakeya] (large wooden hammer) A large wooden hammer used
for driving stakes, etc. Kakeya is also used to tap hozo
(tenon) into hozo ana (mortise) in the wooden-frame
structure method.
[O-hammer] (large hammer) A hammer with a long
handle and a large head. It is used for pile driving andLarge wooden hammer

Crowbardemolition work.
[Bar] (crowbar) A metal tool that can be used as a lever. The Lshaped tip has a groove for removing nails. The tip is inserted
under the nail head, and the nail is removed using the principle ofleverage. The other side is either a claw or flat like a spatula. In addition to pulling out nails, a large
crowbar can be used to lift heavy objects. It can also be inserted into a gap for twisting and prying. A
large crowbar is used in the dismantling of the formwork.
145

5.2.7 Filing/Polishing/Boring[Toishi] (grindstone) A tool for cutting and polishing metals, rocks, etc. The small rectangular-shaped
tools are used to sharpen the blades of nomi (wood chisels) and kanna (Japanese hand planes).
[Yasuri] (file) A tool for polishing metal and wood surfaces. There are many types of files for different
purposes, such as metal files and wood files. If chips get stuck in the grooves, a wire brush is used tocarefully remove the chips.
[Sandpaper] A type of yasuri (file) where sand or glass-like grains are applied onto the surface of
paper. There are several types of paper, including taisui paper (water-resistant paper) that resists watersand nuno paper (cloth paper) that has strength. The numbering indicate coarseness. The smaller thenumber, the coarser the grain, and the larger the number, the finer the grain, resulting in a smootherpolished surface.
[Wire brush] A stiff brush made of metal wires. It can be used to remove rust from metal, peel off
paint, and clean file grooves.
Wire brush

Wire brush

5.2.8 Tightening/Fixing[Monkey Wrench] A wrench with a mechanism that opens andcloses. The width between the upper and lower jaws can bechanged to match the diameter of the bolt or nut. The upper jaw
is integrated with the grip, so the force should be applied to theupper jaw when turning. Because the tip is open, this tool isclassified as spanner, but it uses the word “wrench” as an exception.
146

Monkey wrench

[Socket wrench] A wrench used for nuts and bolts of various sizes by changing the sockets on thehead.
[Box wrench] A wrench in which the socket part for turning nuts and bolts and the handle part are
integrated as a single piece. There are L-shaped and T-shaped types.
[Rokkaku wrench] (hexagon wrench) This tool has a

Hexagon wrenchhexagonal hole and is used to turn bolts. Also called rokkaku bo
wrench.
[Driver] (screwdriver) A tool used to turn screws. There is a
Phillips-head and a flat-blade screwdriver to fit the grooves on
the heads of the screws. It is important to use the correct size to
Screwdriver

avoid breaking the groove of the screw head (called nameru(stripping)). The shape of the grip is also important. For example,
the grip of a screwdriver for electrical work is round and large sothat the hand can easily wrap around it.
[Kugi] (nail) Something that is hammered in to join members together.
Depending on the application, there are various types of nails, such as

Nailscrew nails, concrete nails, casing nails, and corrugated roofing nails.
[Neji] (screw) A cylindrical or conical shaped object with a spiral groovethat is screwed into a member using a screwdriver to secure it to anothermember.
[Tapping neji] (self-tapping screw) A screw that threads its own groove into the material as it is being
screwed.

147

[Bolt] A type of screw. A bolt (male thread) and a nut

Bolt

Nut

(female thread) are used as a set. A washer may also be
used.

Washer

5.2.9 Kneading/Mixing[Hand mixer] A mixer for paint, mortar, and concrete. Ingredients are placed in a mortar box or bucket
and mixed with a hand mixer.
[Kakuhanki] (stirring machine) A machine for mixing liquids and construction materials. Also
called mixers, various types are used in construction sites.
[Mortar mixer] A machine that mixes cement, water, and sand to make mortar. There are two typesof power sources: one that uses a 100 V power source and the other an engine type.
[Concrete mixer] A mixer designed for concrete, with morestrength than mortar mixers.
[Batch Mixer] A mixer that mixes materials for concrete one
batch at a time.
[Torobako] (mortar box) A sturdy box for mixing materials

Concrete mixer

to make concrete or mortar. Also known as torobune or fune. The ingredients in the mortar box are
kneaded using a stirring machine or a kneading shovel.
[Furui] (sieve) A tool with a mesh that can sort materials according to size. Items to be removed aresorted according to the size of the mesh. For example, it can take excavated earth and sand and separate
fine soil from gravel.

1485.2.10 Curing/Prepping[Yojoyo poly sheet] (plastic sheet for curing) Polyethylene film in sheet form. It is used for moistureproofing and waterproofing from the ground when pouring concrete, for curing when painting, and toprotect from rain and dust.
[Veneer] (plywood) Thin plywood is laid to protect the floor from scratches.
[Blue sheet] Used to protect walking areas of the floor from paint and dust.
[Hisan boshi net] (anti-scattering net) A mesh-like sheet for scaffolding that covers the entire
building. It is also used to prevent construction materials accumulated on site from scattering, andcargo from falling off the rear decks of transport vehicles.
[Suichoku yojo net] (vertical safety net) A net attached to scaffolds at construction sites to prevent
materials from flying and falling from scaffolds.
[Suihei yojo net] (horizontal safety net) A net used atconstruction sites to avoid humans and materials from falling

Horizontal safety
netfrom heights.

5.2.11 Scrubbing[Brush] A tool with bundles of bristles planted at regular intervals onto the base, used for rubbing to
remove dirt. For example, in stonework, a brush wetted with water is used to remove the excess cement
slurry from between the stones.
[Sponge] Foam-molded synthetic resin such as polyurethane, wetted with water and used to remove
dirt. For example, in stonework, it is used to clean surfaces dirty from cement slurry.
[Wes] (rag) Cloth used to wipe off stains from machine oil and other liquids.
[Bucket] A container with a handle for holding and carrying water. For construction purposes, sturdy
149buckets made of galvanized steel sheets are used.
[Hishaku] (ladle) A tool with a handle for ladling water.

5.2.12 Carrying Objects[Ichirinsha] (wheelbarrow) A tool for carrying items,

Wheelbarrowconsisting of a steel bucket with one wheel in the front. Usedby holding the handles and pushing. It uses the leverprinciple with the wheel as the fulcrum, the handles as theeffort, and the bucket as the load to make it easier to carryheavy objects. Sometimes called neko.

Wheeledplatform[Daisha] (wheeled platform) A platform with four casters,
used to carry objects. Some have handles and some do not.
A wheeled platform with brakes is also available.
[Sori] (sled) A tool used to move heavy objects such asstones by putting them on top and pulling it.

[Koro] (log) A log used to move heavy objects. Several are placed parallel to each other, an object isplaced on top, and the object is moved as the logs roll.
[Forklift] A vehicle equipped with forks that move up anddown using hydraulic pressure. Objects placed on the fork
are raised to or lowered from high places.

Forklift150

5.2.13 Hanging/Lifting/Pulling[Winch] A machine that winds up a rope. Also called makiageki.
[Wire rope] Several high-tensile-strength steel wires are twisted together to form a strand, and thenseveral strands are twisted together again to form a rope. It has

Wire ropehigh tensile strength, excellent impact strength, and flexibility foreasy handling. Those with processed ends are used for slinging.
There are also ropes for anchoring.

Shackle[Shackle] A slinging fixture for connecting a wire rope or chain
to a suspended load.
[Turnbuckle] A device used to tighten ropes and wires.
ShackleTurnbuckle[Chain block] A machine that can raise and lower heavy objects
by applying the principles of lever and pulley. It is used byattaching it to a tripod, etc.
[Lever hoist] A machine that has the same mechanism as achain block, but is smaller than a chain block. It is used to secure
the load, etc. For example, when a backhoe is loaded onto atruck for transportation, it is also used to secure the backhoe sothat it does not move.

151

Chain blockMain ropetensioner[Oyazuna kinchoki] (main rope tensioner) A device thatcan keep the tautness of the main rope to which the hook of
the safety belt is attached. It is used when working at heights,
such as scaffolding work.
[Tirfor] A manual winch used for pulling heavy objects. The

wire rope passed through the tirfor can be pulled strongly by lever operation. When felling a large tree,
pulling the tree with a tirfor can bring it down in the desired direction.
[Jakki] (jack) A device for lifting heavy objects with a small amount of force. The lifting mechanism
includes screws, gears, and hydraulic pressure.
[Kirin jakki] (screw jack) A device that can lift heavy objects vertically by using the thrust generated
when the screw is turned. It is also used to apply force to the left or right by placing it between two
horizontal members in soil retaining structure work.
[Lever block] A tool for lifting and securing loads. It is also used to re-align steel frames (to makethem vertical).

5.2.14 Work Platforms/Ladders[Hashigo] (ladder) A tool for climbing to high places. It is climbed by stepping onto the rungs. It
should be set at an angle of approximately 75 degrees. If the angle is too steep, there is a risk of falling
backwards. Conversely, if the angle is small, there is a risk of the ladder breaking. Also, always workwith an assistant to support the ladder.
[Kyatatsu] (stepladder) A tool that is a combination of twoladders. When opened, it can be used as a ladder. When using it
as a stepladder, do not sit or stand on the top. Also, do not work
while straddling the top with legs on either side, as this may upset

152

Stepladderthe balance and be potentially dangerous.
Portable elevatedwork platform[Kahanshiki sagyodai] (portable elevated work platform) A toolwith a platform between two legs that extend and retract. Also
known as nobiuma. There are handrails on top of the work
platform. Leaning outward or pushing against a wall may cause lossof balance and falling.
[Rolling tower] A platform for working at heights. There are
casters on all four corners to move it around. There are safety
standards for rolling towers under the Industrial Safety and Health Act.

[Kosho sagyosha] (aerial work platform) A vehicle equipped with a device that can raise and lower
a man basket to a height of 2 m or more.

5.2.15 Cleaning[Hoki] (broom) A tool for cleaning by sweeping. Bamboo branches, bundles of plants or synthetic
fibers are attached to the end of a stick.
[Chiritori] (dustpan) A tool for collecting dust and debris swept with a broom.
Dustpan

Broom

153

[Blower] A blower. It is used to collect light objects such as
fallen leaves by blowing them with the force of air.

154

BlowerChapter 6: Knowledge of Construction Site Work
6.1 Matters Common to Construction Sites
Construction sites are home to technicians from many job categories. Although the work they
perform may appear to be different from each other, experienced technicians are always aware ofcertain matters. This realizes high quality and safety. This section describes matters that all technicians
should know.

6.1.1 Characteristics of Construction Work
(1) Construction work is on a build-to-order basis.
The term build-to-order refers to the manufacturing of a single product designed from scratch tomeet the customer's requirements, rather than the repeated production of the same design in factories,
as in the case of automobiles. Construction work is conducted on a build-to-order basis. They are
diverse, from large-scale to small-scale projects, and although some may appear to be similar, eachindividual project has different characteristics and conditions. It is important to have the intention ofbuilding-to-order for each customer.
(2) Construction work is subject to location constraints.
The majority of construction work is built in accordance to the unique requirements of the locationfor each property, which means that a project will never be repeated under the same conditions.
(3) Construction work is subject to nature.
Construction work is often conducted outdoors and subject to uncertain factors, such as topography,
seasons, weather and other natural conditions.
(4) Construction work is subject to social constraints.
Construction work is local production, and therefore is subject to social constraints on the site. It is
important to manage the site based on safety measures for the surrounding area and environmental
preservation measures. Applicable laws and regulations and the surrounding social environment differ
155depending on the location of construction, and construction work is expected to conform to these
constraints.
(5) Quality is created through safe process.
It is also true in construction work that the quality of the finished structure is created through theentire safe construction process.

6.1.2 Construction Plan
All construction projects have a construction plan. A construction plan is a plan for the construction
project based on the terms and conditions of the construction contract, drawings, specifications, site
descriptions, and other design documents. The construction plan is prepared considering the following
points.
> Planning within various social constraints, such as relevant laws and regulations.
> Comprehensive planning of management methods for quality, construction budget, process, safety,
and environmental preservation.
> Planning to efficiently combine construction methods to achieve good quality at minimum costthat is completed within the construction period.
> Planning for accident-free and disaster-free project that considers environmental preservation.
> Planning using the 5Ms of Construction Management. The 5Ms of Construction Management
refers to Manpower, Materials, Methods, Machinery, and Money.
> Conducting sufficient preliminary investigation to understand the local/on-site conditions, etc.,
and planning measures and management methods prior to and during construction.

6.1.3 Construction Management
Construction management is the management necessary for the contractor to complete the156construction target in the prescribed quality in accordance with the construction plan. Construction
site work is conducted under the following five management indicators (called QCDSE).
[Quality]This is management to produce a finished structure that fully satisfies the quality required by theclient. Quality inspections, quality tests of materials and various construction tests as stipulated in thequality control plan are performed to control the ensure prescribed dimensions and shapes.
[Cost]
Cost is money that can be spent on site. The cost of materials, labor, and field expenses related tothe construction project are managed so that they do not exceed the construction budget.
[Delivery]
Companies coordinate with the prime contractor and other contractors in order to ensure that theirconstruction work can be performed efficiently, and manage the construction process to avoid delaysin the actual work so as to ensure completion within the construction period.
[Safety]
Necessary management is conducted to prevent accidents such as people and objects falling, and toprevent work-related illnesses such as pneumoconiosis and heat strokes. In addition, risk prediction
training in the daily cycle of safety in construction, patrols during work, safe process meetings, 5S
promotion activities, and other activities are conducted with the goal of achieving zero accidents andzero occupational injury.
[Environment]This is management to minimize the impact of construction on the environment, including noise,
vibration, and water pollution. The standards set by laws and ordinances must be observed.

6.1.4 Pre-Construction Preparations（１） Main considerations for the construction procedure manual157

In order to ensure high quality in construction work for the day, it is necessary to check and correctly
understand the construction details.
> Review and understand the terms of the construction contract.
> Review and understand the contents of the contracted construction (terms and conditions of theestimate) and the scope of work.
> Review and understand the blueprints and construction drawings.
> Review and understand the site construction conditions and site rules.
> Review and understand the work schedule with other contractors and connections withconstructions before and after the project.
> Confirm the construction procedures, allocate workers, and prepare materials and equipment.
> Confirm possession and carrying of the Career Up Card and licenses required for the work.
> Identify and understand safety issues.

(2) Pre-work inspection
When working on a construction site, workers use a variety of tools and machinery. Common
accidents for workers occur when handling tools and equipment. Be sure to conduct the following as
pre-work inspection.
> Pre-work inspection of the machinery- Confirm that machinery capable of conducting the intended work are in place, inspected, andmaintained.
> Checking of equipment, tools, and instruments- Confirm that the equipment, tools, and instruments to be used are inspected and maintained.
> Confirmation of work procedures- Confirm that the workflow is realistically feasible.
- Confirm that individual work sharing and collaborative work are assigned in a compatible
158manner, and that the work assignment is correct.
> Confirmation of safety- Confirm that health and safety protective equipment and safety devices, etc. are being usedcorrectly.
- Confirm whether emergency responses are appropriate.

6.1.5 Layout Marking (Marking Out)
Sumidashi (sumitsuke) (layout marking (marking out)) refers to marking the location and height ofthe structure or component to be constructed on the construction site. In the entire construction processfrom beginning to completion, this is the very first step. It is the most important work that requires
quality (accuracy). Precise reference marking and reference level, axis line as per blueprints, etc. aremarked for correct positioning. For layout marking, a tool called a sumitsubo (line marker) is used,
but nowadays a laser illuminator is used to emit a laser beam to mark along the laser. The laser makes
it easy to check for level and right angles. The following are the three main types of layout marking
and marking out work.
Layout marking and marking out

Layout marking and marking out locations

work
Layout marking

Reference and parent markings for positioning, height(reference level/GL), axis line, etc.

Marking out for member fabrication

Cutting and processing dimensions of reinforcing bars,
formwork, piping, wiring, and other components;
processing dimensions of wooden workpieces; and scribe
marks on sheet-metal

Marking positioning of processed

General interior and exterior fittings, intake and exhaustparts, equipment, hardware, etc. forvents such as ventilation holes, water supply and drainage

installation

sanitary piping, air conditioning and sanitary equipment,
and firefighting equipment

1596.2 Construction Knowledge of Each Specialty Work
This section provides an overview of each specialty work and the key points to keep in mind to
avoid accidents and compromising quality. For unfamiliar terms, see Chapters 4 and 5.

6.2.1 Earthwork(1) Excavation work by handFirst, check the excavation site. For example, unstable stones on the untouched ground can fall andcause accidents, so check to see if there are any. Also check for cracks, water content, the presence ofsprings, and changes in freezing conditions. After heavy rain or earthquakes, these factors areinspected again because the conditions may have changed. Also, use lighting when working in darkareas.
Digging into the lowest part of a near-vertical face is called sukashibori (undercutting).
Undercutting should never be done because of the danger of collapsing.
A pickaxe is a tool used for excavation. The pickaxe is a dangerous tool because it has a pointed tip.
Before use, make sure the handle is securely fastened to the head. Also, taking big swings can be very
dangerous because you could hit someone behind you. When two or more people are excavating, makesure to work at a distance. Instead of staying apart vertically, stay apart in the horizontal direction.
Instead of taking big swings, use the pickaxe's own weight for excavation.
(2) Backfilling, compaction, and machine compaction work
It is important that during backfill, the soil is sufficiently compacted. Remove any material left overfrom the previous work in the area to be backfilled. Water, if present, should also be removed before
the work is done. For backfilling, use materials that have been predetermined. Backfilling is done bya depth of 30 cm or less at a time, using a hand roller or other compaction machine to repeatedly
compact the soil.
A rammer is used for compaction of ditches and other narrow areas. When machine-compacting a160

large surface, a tool called a plate is used, which compacts by vibrating a plate with a large surface. A
rammer is a tool used to compact the ground with the weight of the equipment and the impact causedby the up-and-down movement of the ram plate. Always operate the rammer with the rammer in front,
slowly pushing to move it forward. Its impact is very heavy, so be careful not to hit your own feet.
Also, when using a rammer with a power cable, pay attention to the cable routing.
(3) Embankment and cutting soil by handFirst, the slope and finished thickness of the slope are determined by surveying and marking withstakes or other means as reference for the work location. If there are tree roots or water in the area tobe embanked or cut, remove them beforehand. To prevent accidents, do not place heavy objects on topof the slope (the edge of the plane above the slope). Also, pay attention to soil falling down from theslope of the cut soil while working. Check the shape of the embankment and cut soil daily.
(4) Handling water
Handling water is an especially important task in earthwork. If it rains, leave a smooth surface after
the work is done to prevent soil from being washed away by the rain. It is also necessary to takemeasures to prevent rainwater from seeping in by covering it with a sheet or other means. In addition,
make sure that the construction surface is sloped for drainage, and create a drainage path. If facing aroad, install drainage pipes.
(5) Slope protection work
When spraying mortar on to prevent the slope from

Spraying a sloped surface

collapse, spray from top to bottom. The spraying work
should be carried out perpendicularly to theconstruction surface, and with even thickness. The topof the slope is sprayed along the natural ground toprevent rainwater infiltration. When spraying on
bedrock, remove unstable rocks, muddy soil, and debris beforehand. If the sprayed surface is earth or161sand, care should be taken to prevent the pressure of spraying from scattering the earth or sand.
When spraying seeds, soil, and other materials, use specialized machines and make sure to achieve
an even thickness. Turf delivered to the site should be placed as soon as possible. Watering on sunnydays should be done in the morning or evening, avoiding midday.

6.2.2 The Pipe-Jacking Tunneling Method
There are various methods of tunnel construction, depending on the geological characteristics of thesite to be excavated. This section describes the pipe-jacking method of tunneling, where tunnelingmachines are used to excavate underground and construct a tunnel.
Railroad track/Train

Road

River

Jackingpipe
TunnelingmachineJack
Jackingpipe

Jackingpipe

Arrival shaft

Jackingpipe
Launching shaft(1) In pipe jacking, a shaft is first constructed at the starting point of the tunnel to serve as the tunnelingbase and a connection to the ground level. The shaft is used to transport materials required for tunnel
construction down, and send excavated earth up to the ground. Heavy materials and equipment are
carried in and out from within and the top of the shaft.
(2) After the shaft is constructed, the jack to push the jacking pipes into the ground and other temporary
equipment are installed, and the tunneling machine is brought into the shaft.
(3) When the tunneling machine is ready, it is launched from the launching shaft (starting point side)and the tunnel excavation begins. In the pipe-jacking tunneling, factory-made pipes are connected to162the tunneling machine and pushed into the ground with the jack installed in the shaft. Excavation iscontinued by repeating this process until the arrival shaft is reached (end of the tunnel).
(4) Once the tunneling machine has reached the arrival shaft, the tunneling machine, the jack, andother temporary equipment are dismantled and removed. If manholes or other structures are designed
into the shaft, they are usually constructed after this step.
Matters to be considered in the pipe-jacking tunneling method are as follows.
> Inside the tunnel, be aware of the possibility of oxygen depletion and toxic gases. Carbon monoxide
and carbon dioxide are colorless and odorless, so their presence or absence and concentration must be
measured using a detector. Toxic gas measurements must be taken at the beginning of each work shift
to ensure safety. In addition, ventilation must be provided in the shaft and inside the tunnel.
> Pipe-jacking tunneling is often used for sewer and water piping construction with small pipe
diameters, often 0.2 to 3 m in diameter. In addition to the various temporary equipment required forpipe-jacking tunneling, excavated earth and sand are carried out through the shafts. Take care to avoid
being caught-between, hit by flying/falling objects and falling from heights.

6.2.3 Marine Civil Engineering WorkAt marine civil engineering worksites, many different types of work vessels gather to work. This iscalled a fleet. The fleet leader, who organizes the fleet, gives instructions to each work vessel toperform the work. In addition, each work vessel will be directed by a person called the captain or deck
officer.

Fleet (breakwater
construction)163

(1) Preparation of the construction site
Place a buoy to mark the construction site on the sea. This prevents other vessels from coming induring construction.
The work vessels used for construction are moved from the work vessel's base port (the port wherethe vessels are anchored when not working) to the construction site using a tugboat.
At construction sites, anchors at the four corners of the work vessel are lowered and secured using
an anchor handling vessel to prevent the work vessel from being moved from the construction site due
to waves or wind.
(2) Work performed on/by work vessels
The work vessels perform various types of construction work such as dredging, breakwater
construction, and quay wall construction. The following tasks will be performed on the work vesselor at the site at sea[Tamagake sagyo] (slinging) Attaching and detaching wires to loads

Slinging

when lifting them with a crane. In marine civil engineering work,
crane vessels are used to load and unload concrete blocks, stones, andother materials.
[Crane sagyo] (crane operation) Crane operation involves lifting
heavy objects, moving them from place to place, and lowering
them to a different location. The cranes on the work vessels areused for dredging, dumping in uniform riprap, and installing
blocks.

164

Crane operation(dumping in uniform
riprap)[Winch sagyo] (winch operation) A winch is a machinethat can wind up and send out wires. When moving or
securing the work vessel, the winch of the anchor handlingvessel is operated. Also,in breakwater construction,

caissons are installed by winch operation.

Winch operation(3) Safety of marine civil engineering work
Marine civil engineering work cannot be performed when there are large waves, as the work vessels
will be greatly disturbed. When doing construction, it is always necessary to know the weather andwave forecast.
Marine civil engineering works are performed near the sea, on the sea, and on working vessels. When
working, there is a danger of slipping and falling or falling into the water. Also, work vessels are very
narrow and have various machines on them, making it very easy for workers to bump into or trip overthem, which is very dangerous.
> When working on the sea, always wear a life vest. When worn correctly, life
jackets are designed so that when a person falls overboard, his or her mouth
will be maintained above water.
> The ropes on work vessels are dangerous. Do not place your foot among theropes on the deck, or step on them. If the boat moves and the rope suddenly
shifts, the rope can wrap around your leg and cause injuries.
> Boarding and disembarking the work vessel can result in falling into the sea.
Do not jump on or off. Climbing to the wharf froma small boat should be done where there are stairs or
ladders installed, or use a portable ladder.
> When carrying cargo between vessels, a wideayumiita (gangplank) is set up. Only one side of thegangplank is secured to the boat.
165

Example of a lifevest

Example of using an installed
ladder> When mooring a work vessel, the eye (the looped part at the end of the rope) is hung on a shortpost called a bollard, and when doing so, always use an auxiliary rope to prevent fingers frombeing caught in.
> When moving around on a work vessel, only pass

Mooring operation with auxiliary rope

through designated areas and do not enter restricted
areas. Comply with the signs on the working vessel.
> Always keep the work vessel deck organized and tidy.
Also, wipe up any oil spills, as they can cause
slipping and falling.

6.2.4 Well Drilling Work
Small wells are for general household use, and water ispumped manually. Medium-scale wells are installed at
evacuation sites, etc., and water is pumped up using an
emergency generator. Wells used for drinking water mustallow drawing water of good quality.
(1) Preparatory temporary structure
Determine the scope of construction and clear the site. After

Boring survey

clearing the site, the drilling machine is assembled.
(2) Drilling
A boring machine is used to drill straight through to the water-bearing stratum (called taisuiso(aquifer)), making sure not to collapse the stratum. Use the appropriate drilling equipment to excavatein the shortest time possible, according to the strata. The drilled hole is filled with drilling mud madof melted clay to prevent collapsing and to keep the digging debris afloat. Digging debris is removed
by a device called a bailer. The drilling and removal process is repeated until the aquifer is reached.
166

(3) Selection of the aquifer
Once the planned depth is reached, the resistance of the stratum is checked using a method calleddenki kenso (electrical logging), in which an electric current is passed through the hole to determine if
the layer is suitable as a water source. Resistance is lower in clay layers, and higher in sand and gravel
layers with good groundwater flow. Once the aquifer is determined, a device called a screen is installed
to extract groundwater at this location.
(4) Gravel filling
Connect and insert the casing pipes into the hole. The area between the drilled surface and the casing
is filled with sorted gravel or silica sand. This is to control sand, secure the screen and casing, andprevent collapsing of the borehole wall. The depth of the fill, the size of the gravel grains to be used
for filling, and other factors are important, affecting the quality of the finished well.
(5) Finishing
Muddy water in the well is pumped out to allow groundwater to flow out.
(6) Water shielding
Water from the ground surface or aquifers of poor water quality is prevented from entering the well.
(7) Pump installation
A pumping test to determine the amount of water to be pumped and a water quality test to determine
the quality of the water to be pumped are conducted, and the pump is installed.

167

6.2.5 Wellpointing WorkWhen the ground is being excavated for building

Wellpointing work

foundation work, if groundwater flows into the
excavation, earth and sand will flow out of the sides ofthe excavated area and interfere with the construction
work. Wellpointing is performed to lower the
groundwater level in close proximity to the stratum inwhich construction is taking place to create a strong foundation. Pumping will continue until thenecessary construction is completed. Once the foundation work is complete and pumping is stopped,
groundwater will return to the level natural to the local environment prior to construction. The
wellpointing method is suitable for pumping up water at a depth of 2 m to 7 m. For greater depths, thedeep-well method is used.
(1) Investigation and determination of construction details
Investigate how far the groundwater level should be lowered. Based on the results of the survey, aprojection of the drainage volume is made to determine the spacing and number of wellpoints to beinstalled.
(2) Preliminary jetting
Using a jetting pipe, a hole is jetted to the required depth using pressure water from a jet pumpattached to the pipe.
(3) Installing wellpoints
A wellpoint is attached to the end of a riser pipe, and inserted into the previously jetted hole. This
process is repeated at pre-determined intervals.
(4) Connection to the header pipe and installation of the vacuum pump
Connect multiple wellpoints to a header pipe. The header pipe connects to a vacuum pump for
pumping out water.
1686.2.6 Paving Work
If a road to be worked on already exists, it isPaved road structure

subject to general vehicular and human traffic

Asphalt
surface layer

and requires safety measures as specified for
traffic safety facilities, such as the placement ofAsphalt baselayer
Pavement

Aggregate base layer(upper layer)

flaggers, safety cones, security fences, and road
construction signs. A paved road is composed ofAggregate baselayer (lower layer)

Subgrade layer

four layers. The construction will be divided into
four processes, one for each layer.
(1) Subgrade layer work
The lowest level of the road is called rosho (subgrade layer). When thick, it can be about 1 m deep.
A backhoe or bulldozer is used to dig into the ground. Because different operations are performed
simultaneously over a short distance, such as excavating with a backhoe, loading excavated soil onto
a dump truck, compacting with a hand roller, spreading and compacting gravel with a bulldozer, andcompacting with a road roller, be mindful of avoiding accidents including collisions with heavyequipment, entanglement, and being crushed.
(2) Aggregate base layer construction
The aggregate base layer is the middle layer of a paved road, divided into upper and lower layers.
Crushed stone or other materials are placed over the subgrade layer to disperse loads and impacts.
Although not seen at worksites, a machine called jaw crusher is used to crush stones into small pieces,which is brought in and used. Crushed stones are scooped up from dump trucks with a backhoe or
excavator buckets and spread on the subgrade layer. Workers leveling crushed stones with rakes areoften working at the same time, so care must be taken to avoid accidents.
(3) Asphalt base layer construction
The asphalt base layer is the layer above the aggregate base layer. The heated asphalt is spread and169

leveled with an asphalt finisher. The asphalt finisher is a machine that discharges asphalt in the hopperfrom the back. The edges of the road are leveled by hand using a tool called tonbo (asphalt rake). The
spread asphalt is compacted with a macadam roller or other machinery, and further compacted with atire roller. By using two different machines, it is possible to compact not only the surface but also theinterior.
(4) Asphalt surface layer construction
The asphalt is spread using the same method as for the base layer construction. The asphalt used inthis process differs in nature from the asphalt used in the base layer construction, having high water
resistance and non-slip properties.

6.2.7 Mechanical Earthwork
Mechanical earthwork is earthwork performed using construction machinery. If multiple machines
or workers will be working on the same construction site, make sure there are no other vehicles or
people around before commencing work. When getting in and out of vehicles, be sure to turn off theengine and lock the safety lever. In addition, during machine cutting operations, the direction of themachine's undercarriage should be oriented at a right angle to the cutting edge as a general rule.
When transporting machinery to the construction
site, a vehicle dedicated to machine transfer is used.
A ramp called tohan yogu (loading ramp) is installedon the transfer vehicle for loading and unloading.
The ramp should be securely attached to the loading

Loading
ramp

Vehicle fortransporting
machinery

bed with a slope of 15 degrees or less. Since tipping over a machine can cause a fatal accidents, thesurrounding area must also be kept off-limits.
Because mechanical earthwork often generates noise and vibration, measures such as using
teishindogata kensetsu kikai (low-vibration construction machinery) that have been designated as low170

vibration/noise construction machinery according to the regulations of the Ministry of Land,
Infrastructure, Transport and Tourism, are taken.
In order for the construction work to be carried out as planned, machines must function properly
without malfunctioning. At the end of the day's work, park in a safe place, and lower buckets and otherattachments to the ground. Once the safety lever is in the locked position, allow the machine engine
to idle for about five minutes while stepping off the machine and check for oil leaks, coolant leaks,
etc.. Abnormalities are to be reported to the person in charge of maintenance, and the results of daily
maintenance are recorded in the inspection chart. Even though inspections are performed after work
is completed, it is required by the Occupational Health and Safety Law that brakes and clutches beinspected before commencing work.

6.2.8 Piling Work
(1) Preliminary investigation of underground objects and facilities
Before piling work begins, a survey of the buried objects is required. For example, if there are buriedgas, water, or power lines in the area where the holes are to be dug, it could cause a major accident.
Presence of large rocks and hard bedrock requires specific methods of excavation and machines. If
important archaeological sites or cultural assets are buried, archaeological excavation and otherresearch will be required.
(2) Geotechnical survey
In addition to investigating underground objects and facilities, a geotechnical survey of soil quality,
soil strength, and groundwater level is also required. A boring machine is used to dig deep holes andcollect soil samples for investigation and determination.
(3) Safety precautions
Foundation construction involves the use of large machinery, which can pose a variety of hazards.
Most accidents are caused by errors in work procedures, unstable machine locations, falling machines171or materials due to loss of balance, slipping/tripping or falling into openings due to careless steppingor backward movements, or being caught-between by entering an area that is off-limits. To avoid
accidents, it is important to check above and around, pay attention to moving machinery, and alert
other workers.
- Danger of falling objects
Incorrect procedure when using a pile driver, such as removing the wire before inserting the pin,
could result in the screw detaching from the joint and falling off. Also, when using a vibro hammer todrive in or pull out H-beams or sheet piles, the H-beams or sheet piles could fall.
- Danger of being caught-between
When a pile driver or crane is in motion, if the machine is operated incorrectly or if a worker enters
an off-limits area, there is a risk of being caught between the suspended H-beams, sheet piles, theleader, etc. and other surrounding objects.
- Danger of tipping overDepending on the location of large machines, they may lose their balance and tip over.
- Danger of falling from heights

Safety precautions for earth drilling work
Open and close thebucket only when there
are no possible dangers

Indicate off-limits zones

Guiding worker

Signaling
worker

Install steel road plates

Although foundation work is not performed at height, and thus there is little risk of falling fromheights, falling into excavated holes due to inattentive backward movement and falling frommachinery such as when performing joint work on a pile driver leader are possible accidents. In
172

addition to wearing non-slip shoes, it is important to receive work instructions from the work
supervisor.

6.2.9 Scaffolding WorkAs explained in Chapter 3, there are many different types of scaffolding work. This section describes
scaffolding construction. There are several types of scaffolding, including timber scaffolding, tube
scaffolding, framed scaffolding, and ringlock scaffolding, but there are some construction tips that arecommon to all types of scaffolding work. It is to make sure that the footing is secure, then assemble itso that it is vertical and level, and diagonally brace it to keep it straight. To prevent the entire scaffold
from collapsing, when there is a building, it is secured to the building with kabetsunagi (wall tie
anchors). When there is no building, it is braced with circular hollow sections or other means.
(1) Foundation of scaffolding
The ground on which the scaffolding is erected is compacted for strength. If even one upright tube
sinking can cause the entire scaffold to collapse. In addition, the ground is made as flat as possible sothat there are no gaps between the mudsill and the ground.
(2) Fixing the legs
The base fitting is nailed to the mudsill laid on the
ground.

Mudsill(3) Installation of upright tubes and planks
Base fitting

Upright tubes are erected vertically, and planks
should be attached perpendicular to the uprightUpright
tube

Working
platformtubes. The footings of the upright tubes areconnected to each other by horizontal members toBeamsecure them.

Plank

173

(4) Installation of beams and working platform
Connect the upright tubes on the front side (the building side) and the rear side (the outside) using
braces, and attach the scaffold board (working platform) on top of it.
(5) Installation of stairs, handrails, middle and lower ledgers, and toe board.
Install handrails for workers, middle and lower ledgers for fall prevention, and toe boards to prevent
tools and other items from falling. Handrails are also installed for stairs.
(6) Installation of cross braces
Install large cross braces to keep the entire scaffold vertical and level.
Cross
brace

Handrail
Lower ledger

Toe board

Stairs(7) Installation of wall tie anchors
To prevent the entire scaffold from collapsing, it is secured to the side of the building with wall tie
anchors. If there is no building, diagonal supports (yarazu) are installed using circular hollow sections
or similar members.

6.2.10 Steel Framing WorkIn steel framing work, steel sections are assembled to complete the framework of a building. It is
performed in the order of steel section fabrication, foundation frame construction, and steel section
erection.
(1) Steel section processing
The steel sections are fabricated in the factory. A construction plan is drawn, and the steel sections
174

are cut accordingly. The cut steel sections are assembled and welded, and the welds are inspected byultrasonic testing. After inspection, they are coated with rust-proofing paint and transported to theconstruction site.
(2) Foundation frame construction
Anchor bolts are secured to the nonstructural concrete withanchor bolt stands or other means. This is followed by the

Example of base plate
installation

placement of the underground beams and foundation
reinforcement, foundation formwork, and foundation concretepouring.
(3) Steel frame erection
Steel columns and anchor bolts fixed to the foundation
Steel section

are joined to each other by a member called a base plate.
Foundation work in steel construction is just as important

Anchor bolt

Base plateNon-shrink mortaras that in scaffolding construction. For example, foundation
Foundation

heights may vary slightly, which, if not adjusted, will affectthe accuracy of the overall building finish. Check the height

Fixing steel frames with baseplatesof the foundation and match the base plate height of allcolumns using non-shrink mortar or layers of thin steel plates. After making sure the mortar has set,
check the orientation and bolt the columns in place.
There are two methods of fastening the upright members to the beam: bracketed and non-bracketed.
In the bracketed method, the beam is divided into three sections, and the two ends of the beams andthe columns that cross those ends are bracketed together by welding or other means at the factory. The
non-bracketed method is a construction method in which columns and beams are joined directly on
site.
The intersection of columns and beams are bolted and then welded. If the holes for the bolts do not175match, a tool called a drift pin is used to align them before securing the bolts. At this stage, the nut is
temporarily fixed.
By adding beams, the columns will be pulled and will not be able to maintain their verticality. The
frame is pulled with wires to re-align the steel frames, then the nuts are tightened properly, and thenthe intersection is welded (stud welding).

6.2.11 Steel Reinforcement Work (Rebar Work)
Concrete is resistant to compressive forces but weak against tensile forces. Because of its tensile
strength, rebar can be placed in concrete to compensate for the weakness of concrete.
Rebar can oxidize and rust. Concrete is alkaline, which
protects the rebar from rust, but over time it will become more
and more neutral. If neutralization progresses to the rebar, therebar will rust. Therefore, when placing the reinforcement, it
is important to ensure a certain distance from the surface ofSlab concrete cover
thicknessthe concrete, or kaburi (concrete cover thickness).
In order to maintain strength, it is necessary to use rebar of
Pitch confirmation tapea specified thickness and to distribute the rebar with proper
spacing between the rebars. Tape is wrapped around the rebar
to make it easier to check the pitch.
In the case of thin slab rebars, the bars are joined by amethod called rebar lapping. This joint method gains strengthfrom the concrete's adhesion to the rebar, but because the strength of the concrete affects the strengthof the joint, make sure to secure a sufficient length of overlap and secure the bars with binding wires.
Rebar work is involved throughout the entire construction in a typical RC structure building. In
particular, it is closely related to formwork carpentry, and the processes need to be coordinated with176

each other. In addition, meetings with electric technicians will be necessary for piping and wiring workfor electricity and equipment, and with plumbing technicians for water supply and drainage. Rebar
work is performed in the following order: rebar fabrication, foundation reinforcement, and floor slab
reinforcement.
(1) Rebar processing
Construction drawings are based on structural drawings calculated by a structural design specialist.
From the construction drawings, the required shapes and sizes of rebar and the required number of
each are calculated, and a reinforcement detailing is created. Rebar is cut, bent, or otherwise processed
according to the reinforcement detailing. In addition, bar tags are created based on the reinforcement
detailing. Bar tags are attached to the fabricated rebars and are used for sorting and receipt inspection
at the time of delivery.

Rebar bending

Rebar cutting(2) Foundation reinforcement
Rebar delivered from the processing plant is inspected upon receipt and organized for ease of
retrieval in subsequent operations. The foundation reinforcement work begins by layout marking theexact location of the foundation onto the nonstructuralconcrete. After layout marking is complete, embedded
beam bearing brackets are lined up to keep the main beambars of the foundation at a level height, and secured withnails or anchors for nonstructural concrete. Spacer blocks

Foundation beam
reinforcement

are used to lift the base reinforcement to ensure cover
thickness. After the base reinforcement, the column reinforcement is placed. A column consists of a177main rebar placed perpendicular to the ground and hoop rebars surrounding the main rebar. Hoop
rebars are installed to reinforce against shear and to prevent the main bar from shifting due to shaking
caused by earthquakes and other shocks. Once the column rebar and hoop rebars are bound, spacers
are installed to secure the cover thickness. After the column rebars, the beam rebars are placed. Afterall the foundation reinforcement is completed, the formwork is erected and the foundation concrete ispoured.
(3) Reinforcement of doma (ground under the house)
Typically, pipe burial and backfilling are performed prior to doma reinforcement. Doma
reinforcement is placed in the following order: main rebar placement, distribution rebar placement,
and installation of spacers. After completing the doma reinforcement, the doma concrete will be
poured.
(4) Frame reinforcement
The frame provides the reinforcement for the walls, beams, and slabs.
Wall reinforcement is placed in the following steps: checking the cover thickness, checking theinternal/external relationship of longitudinal and transverse reinforcement, allocating the pitch andplacing reinforcement, placing reinforcement for openings reinforcement, placing spreader rebars, andplacing spacer blocks.
Beam reinforcement is placed in the following order: placement of bottom rebars, temporary
placement of hoops at the ends, placement of top rebars, placement of bottom and top rebars of small
beams, pressure welding, placement of stirrups and tying to top rebars, placement of side and spreader
rebars, dropping into the formwork, and placement of spacers.
The slab shall be doubly reinforced with bottom and top reinforcement consisting of main rebars
and distribution rebars.

178

<Basic composition of beams>

Top rebars

StirrupSpreaderrebarsSpacerSide
rebarsWall formwork

Dropping in

Bottomrebars

6.2.12 Rebar Splicing Work
There are several types of rebar splicing methods, but no matter which method is used, the spliced
joint must have strength equal to or greater than that of the base rebar. For example, the splice cannot
be detected when viewing a cross-section of a perfectly
executed gas pressure welded splice, and when a tensile orbending test is performed, the splice does not break, butinstead the base rebar does. The following steps are used tocheck the process while performing pressure welding.

Tensile test

(1) Checking rebar butts
Check for bends in the rebar.
(2) Processing of rebar butts
Rebars are cut by push-cutting at steel construction sites, and therefore their butts are unsuitable forpressure welding as they are. Since the cut surface oxidizes over time, the rebar is cut using a coldcutting, right-angle rebar cutter on the same day that pressure welding is performed.
(3) Mounting onto the welding fixture
Make sure the welding faces of the rebars are clean before setting them to the welding fixture using
179

bolts. Because high pressure is exerted onto the rebar during the pressure welding process, the bolts
should be securely fastened so that they do not loosen during the course of the work. When fixing,
check the size of the gap between the butts to be pressure welded.
(4) Heating and pressurizing
First, the part where the rebars are butted together is heated with a burner, and the heated portion is
gradually expanded to the left and right. The approximate range to be heated is about twice thediameter of the rebar. Simultaneously with heating, pressure is applied to press the butts together. The
butts will gradually bulge out, and the work is finished when they reach a predetermined size.

Work process of gas pressure welding
Hold
Cleaning

Reducingflame

Initialpressurization

Reducing
flame

Neutralflame

Neutral
flame

Apply
pressure

Bulge formation(5) Inspection
The size, length, shaft misalignment, bending, cracks
and dents on the exterior, and bulkiness of the bulge are allinspected.

Examples of bad bulging

180

6.2.13 Welding WorkArc welding is a necessary technique in many areas of construction work. If the current is too low,proper welding cannot be performed. If the current is too high, the member will melt and create a hole.
Proper and constant distance should be maintained
Arc welding work

between the welding rod and the material to bewelded, without getting too close. A proper weld willproduce a weld scar that looks like a line of shells.
Welding is an easy task for anyone to do once thebasics are mastered, but it is important to takeprecautions against physical effects and accidents.
Arc welding uses electrical power to weld metals together, so avoiding electric shocks is the priority.
Even more important is the prevention of effects on people. Inhalation of fumes from welding (metal
vapors cool and solidify in the air and become individual particles floating in the air, which appear
like smoke) can cause symptoms such as headaches, fever, chills, muscle aches, thirst, and fatigue.
Dust masks should be worn to prevent fume inhalation. Also, wear light-shielding glasses or welding
face shield to protect your eyes from harmful rays. The welded area is polished with a grinder, at whichtime metal dust adheres to gloves and hands. Avoid rubbing your eyes polishing, as rubbing your eyes
can damage them.

6.2.14 Formwork Carpentry
When fresh concrete is poured into a formwork, theformwork is subjected to several times the pressure of
the same volume of water. Insufficient reinforcementof the formwork can lead to accidents where theformwork breaks (blow-out) and ready-mixed
181

Formwork carpentry

concrete flows out. In order to prevent blow-outs, the formwork must be adequately reinforced towithstand the pressure of the concrete. Also, since placing concrete from height may result in a blowout, a detailed discussion is held with the concrete pumping contractor regarding the concrete
placement method.
The formwork should be erected in the correct position, vertically and leveled, and should beassembled so that it can withstand loads, lateral

Tightening form ties

pressure, vibrations, impacts, etc., without significant
deformation or damage.
Wall formwork should be made from materials suchas separators, form ties, and P-Con to ensure that there
are no misalignments or errors. Form ties can also betightened through circular hollow sections to make them stronger.
The slab is supported vertically from below because the weight of the concrete will be applied
directly in the vertical direction. The materials used are, from the bottom, pipe supports called shoring,floor joist hanger, and floor joist, on top of which formwork plywood (also called sekiita in formwork
carpentry) is attached.
<Slab structure>

Floor joist
hangerFormwork plywood

Floor joist tube (circularhollow section)

Pipe support

A sufficient number of pipe supports are required to support the slab. To prevent the shoring fromsliding, the footings are connected in two horizontal directions by pipes called negarami. If the pipe
support is longer, horizontal joints are installed using every 2 m or less in height using circular hollow
182

sections. Finally, the chain, turnbuckle, and support are used to push and pull while checking theverticality and the axis line as adjustments are made.

6.2.15 Concrete Pumping Work
Concrete pumping work involves pouring ready-mixed

Acceptanceinspection

concrete delivered by truck agitators into formwork using
pump trucks. The ready-mixed concrete brought inundergoes acceptance inspection (slump value, air content,
and chloride content) based on the ready-mixed concretedelivery note, and a test piece for compressive strength inspection is prepared at the same time.
An important thing to do before starting the pouring
work with the pump truck is to prepare the ground to put
out the outriggers that secure the pump truck so that it will
not fall over. To prevent the outriggers from sinking into
the ground due to vibration, the outriggers' jacks are

Concrete placement by a pumptruck

supported by the receiving wood on solid ground, and on
softer grounds, the pump truck is installed by laying a steel plate and then opening the outriggers totheir maximum width. In addition, tire stops should be securely inserted. On sloping terrain, adjust theoutriggers' jacks so that the horizontal angle is within 3 degrees both front to back and left to right.
During construction, care must be taken to avoid contact with or cutting power lines due to boom
movement. In the case of high-voltage wires, even without direct contact, the spark discharge may
cause electricity to flow and cause electric shocks. Check and observe the safety clearance distance(distance away from the wire).
It is also important to inspect the delivery pipes and check connections. If a delivery pipe ruptures,
ready-mixed concrete will flow out, leading to an accident. It should be inspected on a daily basis by183

tapping (checking the sound when tapped) or ultrasonic thickness gauge. Pipes are to be handled
carefully to avoid damage during loading and unloading.
Before placing the ready-mixed concrete, a primer is sent through the delivery pipe first to makethe inner wall more slippery. This primer is discarded, because when cast into the formwork, it
compromises the strength and quality of the concrete. About 1.5 times the amount of the primer,
including the primer, is not placed in the formwork, but instead discarded.

6.2.16 Painting Work
There are many different types of painting work. The important thing common to all types is tomake sure that the paint adheres well to the painted surface. If the work is not done properly, problems
such as the paint film cracking or peeling and loss of luster will occur after one to three years.
Painting is basically divided into three processes: primer, middle coat, and top coat. It is importantthat appropriate amount of time is passed between each step of the process in order to let the paint dry,which is called the process interval period. The time between painting processes must be at least as
long as specified for each coating, and the coating must be allowed to dry thoroughly before moving
on to the next painting process. Process interval periods vary depending on a variety of conditions,
including temperature, insolation and humidity, and the worker must be able to assess the situation inproceeding with the work. Construction should not be performed when the humidity is 85% or higher,such as during rainy weather.
Before starting priming, make sure the painted surface is free of debris. This process is called keren(scraping). If the exterior walls are to be painted, dust and dirt should be removed by high-pressure
washing or other methods, and cracked areas (cracks) should be repaired.
The primer coat is applied to improve adhesion between the substrate and the middle-coating
material. Sealer, primer, filler, and other priming materials are chosen for different purposes.
The middle coat smooths out surfaces that have become uneven due to scratches or cracks in order184

to achieve an even finish. It can also reinforce and enhance adhesion of the topcoat material.
The top coat is the final stage of the painting process, and its finish demonstrates performance inweather and stain resistance as well as design for
Spray painting

aesthetic purposes. The performance of the painting
work is determined by three layers of paint (primer,
middle coat, and top coat), but is generally evaluatedbased on the performance of the top coat paint. In
spray painting, the surface usually receives two coats.
Paint should be applied only where necessary, and therefore, do not forget to cover the areas that do
not need to be painted. Cover the floor with a polyethylene sheet, apply masking tape to the border of
the area to be painted, and use masker tape to coverlarge surfaces such as walls. In addition, in exterior

Covering work

wall painting, paint can splatter onto cars, etc.,
causing problems. The entire building should becovered, and automobiles and other vehicles within
the area where paint is likely to splatter are also
covered with sheets.

6.2.17 Landscaping Work
Landscaping is the designing of space through placement of natural stones, trees, plants, and flowers.
Landscape architects, sometimes called niwashi (gardener), create gardens and residential yards basedon traditional Japanese landscaping culture. In recent years, landscaping techniques have also beenrequired for the greening of building rooftops, wall surfaces, and artificial grounds. Landscapearchitects are required to have not only knowledge and skills in planting, diagnostic for plants andplanting substrates, and transplanting, but also artistic and design capabilities. In particular, pruning
185

trees in the garden affect the finished landscape, and therefore must be discussed in detail with theclient in order to avoid complaints. It is also important to know that different trees have different
pruning timing. Pruning at the wrong time can cause the plant to die or not bloom.
Landscaping requires a lot of work at heights. Working on an unstable ladder or stepladder cancause falling accidents. Choose a stepladder location for stability without wobbling, and take measures
to prevent it from falling over, such as by tying and securing the stepladder to the trunk of a tree.
Working on top of a branch can result in a falling accident when the branch breaks. If the heightexceeds 2 m, use a safety belt.
Crane trucks are used to move plants and garden stones, and drag shovels are sometimes used for
excavation work. Take ample care to prevent the machinery from tipping over. There have been
accidents such as being entangled in self-propelled mowers, being trapped under a falling tree when
felling trees with a chainsaw, and receiving direct hits to the head.

Pruning

6.2.18 Demolition Work
Demolition work is performed on structures of all sizes. There are two methods of building
demolition: block kaitai koho (floor-by-floor demolition) and happa kaitai koho (blast demolition).
Here, the floor-by-floor demolition will be explained. Demolition will begin only after confirming that
all lifeline infrastructure (electricity, telephone, fiber optic cable, cable TV, gas, water, sewage, etc.)
are shut off. For example, demolition with active gas, water, and sewage lines can lead to major
186

accidents. The demolition work will proceed in the following steps.
(1) Demolition of exterior areas
Remove items from around the building to make the work easier. It is necessary to confirm what is
to be demolished, as there may be items on the property that are not subject to demolition.
(2) Installation of scaffolding and soundproofing
panelsInstall scaffolding for the demolition workers. The
entire surface is covered with soundproofing panels,
soundproofing sheets, etc. to prevent noise andSoundproofing
sheet

scattering of dust from demolition.
(3) Demolition of the building interior
Remove fittings, plaster boats, sashes, and various equipment by hand. At this time, separate
recyclable material. In order to utilize resources through recycling and to curb illegal dumping ofwaste, the Construction Material Recycling Act establishes standards and penalties for demolition ofbuildings with a floor area of 80 m2 or more.
(4) Drilling holes in floors on each floor
Drill holes in the floor to allow the demolished walls and structural debris to be dropped down.
(5) Installation of support for heavy machinery
Walls and columns are dismantled by hoisting heavy equipment upward. Provide supports towithstand the weight of heavy equipment.
(6) Demolition of walls and structure, excavation and demolition of the foundation
Because digging up foundations is an underground construction process, vibration is inevitably
generated. It is important to choose the right time of day to conduct this work.
(7) Disposal of waste, removal of debris from the ground surface, land clearing, and street
cleaning
187

Recyclable materials are taken to a disposal site, and the ground is cleared of debris. The
surrounding streets dirtied by the work are also cleaned and restored to their original condition.
The above is a method of demolishing from the top, but there is also a method of demolishing fromthe first floor while supporting the severed columns with jacks. Not only does it eliminate the need forsupport installation work in (5), it also allows for efficient removal and sorting of demolition materials.

188Chapter 7: Safety during Construction Work
7.1 Fatalities in Construction WorkA variety of industrial accidents occur at construction sites. Table 7-1 shows the number of fatal
industrial accidents in the construction industry in 2021 by major accident type, based on the data
released by the Ministry of Health, Labour and Welfare. Among the various types of industrial
accidents that occur, fall from heights, accidents involving construction machinery and cranes, andcrumbling/collapsing are the three major accidents in the construction industry, accounting for 4070% of all accidents. Most of the struck-by and caught-in/between/entanglement cases in the tablebelow are accidents involving construction machinery and cranes.
The most common of the three major disasters is fall from heights, occurring while working in highplaces. Aside from the three major disasters, the most common type of accident is traffic accidents that
occur while traveling on public roads. Chapter 7 describes the types and causes of accidents that occur
on civil engineering construction sites, as well as countermeasures and how to be mentally prepared.

Civil engineering work

Fall fromSlipping/tripping/falling/tippingheightsoverCrashing

Flying/falling

Crumbling/Collapsing

Struck-By

CaughtIn/Between/Entanglement

Contact with
Drowning

hot/cold
objects

Exposure tohazardous

Electric

substances,

shock

etc.

Traffic

Traffic

accident

accident(road)(other)

Total

19

5

1

4

13

11

15

9

4

3

2

10

1

102

Tunnel construction

0

0

0

0

1

0

0

1

０

0

0

1

0

3

Bridge Construction

1

0

0

0

2

0

1

2

０

0

0

0

0

6

Road Construction

3

0

1

1

2

1

2

0

1

0

0

5

0

17

River engineering work

1

3

0

0

1

1

1

2

0

1

0

0

0

10

Erosion-control work

2

0

0

0

0

1

0

0

0

0

0

1

0

4

Harbour/coastal

0

1

0

0

0

0

1

2

0

1

0

0

1

6

Other civil engineering

9

0

0

2

4

8

8

2

3

1

2

1

0

44

71

0

0

5

15

7

6

0

6

5

2

9

0

139

23

0

0

3

5

2

0

0

3

4

0

5

0

48

Wooden-frame house construction

12

0

0

0

1

1

0

0

0

0

1

1

0

19

Building equipment installation

8

0

0

0

2

0

0

0

0

0

1

2

0

16

Other building work

28

0

0

2

7

4

6

0

3

1

0

1

0

56

20

0

0

1

3

1

6

1

1

1

4

6

0

47

Telecommunications work

4

0

0

0

1

0

2

0

1

0

2

2

0

13

Machinery and equipment

4

0

0

0

1

0

0

0

0

0

0

0

0

6

12

0

0

1

1

1

4

1

0

1

2

4

0

28

110

5

1

10

31

19

27

10

11

9

8

25

1

288

Building work
Steel frame and reinforced concrete
housesOther constructions

installation
Other constructions
Construction industry subtotal

Table 7-1 Fatal Industrial Accidents in the Construction Industry in 2021 by Major Accident Type(Compiled from the Ministry of Health, Labour and Welfare's Workplace Safety Website)189

7.1.1 Fatalities and Injuries in Construction
Table 7-2 shows the number of fatal accidents involving foreign workers in all industries in FY2020
and FY2021, as compiled by the Ministry of Health, Labour and Welfare. Table 7-3 shows that theconstruction industry has the highest numbers.
Accident Type
Fall from heights
Slipping/tripping/falling/tippingover
Crashing
Flying/falling
Crumbling/Collapsing
Struck-By
CaughtIn/Between/Entanglement
Exposuretohazardous
substances
Electric shockFire
Traffic accident (road)
Drowning
Other
Total

Number of fatalities
FY 2020
FY 2021
5
5
2

0

1
1
3
4

0
2
3
2

2

3

2

0

2
0
7
0
1
30

1
1
4
1
2
24

←Table 7-2 Occurrence of Fatal Accidents ofForeign Workers in All Industries

Industry Type
Manufacturingindustry
Constructionindustry
Other
Total

Number of fatalities
FY 2020
FY 2021
3

8

17

10

10
30

6
24

Table 7-3 Number of fatalities by industry[Tsuiraku/tenraku] (fall from heights) These are industrial accidents caused by falling from highplaces, falling down shafts during construction, or falling down a hole during excavation.
[Tento] (slipping/tripping/falling/tipping over) Industrial accidents caused by tripping over objects
or losing one's balance and falling.
[Gekitotsu] (crashing) Industrial accidents caused by a violent collision with something.
[Hirai/rakka] (flying/falling) Industrial accidents caused by loads being lifted by a crane falling, or
tools or materials falling from a high place.
[Hokai/tokai] (crumbling/collapsing) These are industrial accidents that occur when a scaffold
crumbles or a building under demolition collapses.
[Gekitotsusare] (struck-by) Industrial accidents caused by being struck by heavy machinery that is
running, by a circling bucket, etc.
[Hasamare/makikomare] (caught-in/between/entanglement) Industrial accidents caused by being190caught or entangled in machinery.
[Yugaibutsu tono sesshoku] (exposure to hazardous substances) Industrial accidents that occur
when hazardous substances, such as chemicals, come into contact with the human body.
[Kanden] (electric shock) Industrial accidents caused by electric current flowing through the body,for example, by cutting an energized wire or touching a leaking device.
[Kasai] (fire) Industrial accidents caused by being caught in a fire started by a variety of factors.
[Kotsu jiko (doro)] (traffic accident (road)) Industrial accidents that occur while commuting to andfrom construction sites, and industrial accidents that occur when a worker is involved in a generalautomobile accident during construction work next to a road.
[Obore] (drowning) Industrial accidents that occur by falling into water in places where water is apart of the work, such as oceans, rivers, and sewerage works.

7.1.2 Types of Fatal Accidents(1) Fall from heights
Fatalities from falling from heights do not always occur in crashes
from extreme heights, but can also occur in lower places, such as
falling from the back of a dump truck. There have also been
accidents of falling into excavated holes. Since falling often occurs
due to loss of balance or slipping, full-harness fall protection gear
should be worn properly at high altitudes. Also, be sure to use them, accidents have occurred when thegear is worn but not used.

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(2) Struck-By/Caught-Between
Civil engineering work is prone to heavy equipment
disasters because the work often involves the use of large
construction machinery. Accidents involving being runover or caught-between by construction machinery, as wellas tipping over and falling of construction machinery, are common. Backhoes have caused accidents
such as collision between the circling arm/bucket and a person, ora person getting caught between the bucket and an object.
An accident also occurred when a flagger of another vehicle
failed to notice a dump truck backing up and got caught-between.
In addition, accidents have also occurred, such as a dump truck
flicking up the mudsill laid out on the site's loading ramp and hitting a flagger.
A backhoe tipping can result in fatal accidents when someone
is crushed by it. In addition, backhoe tipping accidents are more
likely to occur when loading and unloading backhoes onto and
off trucks, etc.
Falling and tipping over of construction machinery can also
occur while traveling on a ramp or by falling off the shoulder of a road. Paths for construction
machinery should be wide enough to prevent the shoulder from crumbling. Tipping over can also occur
when trying to lift heavy objects with a backhoe. Construction machinery, including but not limited tobackhoes, should not be used for purposes other than those for which they were originally intended.
(3) Traffic accident (road)
Fatalities from traffic accidents, not limited to construction work, are also common in construction,equipment, and lifeline infrastructure projects. Many
traffic accidents occur while commuting to construction
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sites, and some traffic accidents occur when construction vehicles are traveling on public roads.
Accidents include being hit by another vehicle while loading or unloading goods on a public road, ora dump truck carrying a load of surplus soil driving too fast and overturning on a curve.
(4) Flying/falling
A flying/falling accident occurs when a person is hit by a flying
or falling object. For example, being struck by the object carried
by a crane or becoming trapped under a falling suspended load.
Insufficient slinging, moving suspended loads, etc. can cause
accidents. The important thing is not to ever go below suspended
loads. Accidents have also occurred due to falling tools and components to be installed.
(5) Collapsing/Crumbling
Because civil engineering work involves dealing with nature, accidents due to landslides and falling
trees have occurred. Accidents can occur especially in excavation work, where the soil wall cancollapse.

7.1.3 Work with A High Number of Fatalities(1) Characteristics of and accidents in road
Paving work

construction
The photo on the right is of road paving work. Behinda line of several construction machinery moving forward,
several workers are leveling asphalt. Road construction
accidents include collision with rollers and being hit bydump trucks backing up. Accidents also occur during paved road repair work by colliding withbackhoe arms and buckets. Road construction is characterized by construction machinery and people
working in close proximity. Flaggers are assigned to ensure the safety of the workers by signaling with193

the operators of the construction machinery, but the workers themselves must also be constantly awareof the safety situation of their surroundings.
(2) River engineering work
The most common accidents that tend to occur

River engineeringworkin river engineering work are those related toconstruction machinery and vehicles. At these
construction sites, accidents such as backhoes
tipping over from slopes or people being run overby moving vehicles can occur. Large blocks areoften used, and accidents can occur during liftingand moving operations of crane-type backhoes.
(3) Bridge construction
Bridge construction often involves working atheights. As a result, accidents due to fallingfrom heights and being hit by flying/falling
objects are more likely to occur. As a result,
accidents due to falling from heights and being
hit by flying/falling objects are more likely to

Bridgeconstruction

occur. Accidents also occur when a worker's
foot is caught on a circular hollow section temporarily fixed at the upper part of a bridge, causing theformwork to come loose and fall down. Such an accident was caused by an attempt to climb up usinga passageway other than the one provided. The general rule in fall prevention is to wear and reliably
use the full-harness fall protection gear. Falling can also be caused by tripping and losing one's balance.
In addition to watching your step, it is also important not to place unnecessary objects in thepassageways.
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(4) Tunnel construction
As discussed in Chapter 3 Section 3.1.1, there are a variety of tunneling methods that can be used
depending on geological and environmental conditions. The geology, construction machinery used,
and temporary facilities necessary differ by method, so there are some differences in safety
considerations, but there are also many similarities. In tunnels, excavated soil is removed and materials
are transported by railway equipment and dump trucks in a narrow, dark environment, and many
vehicles drive through the tunnel as workers work. As a result, many accidents involving heavymachinery occur. Although the geology differs, fragile geology such as sandy earth and weatheredrocks are also excavated, which can lead to collapses of strata disturbed by the excavation work,
resulting in rockfall accidents. In tunnel excavation, it is important to carefully observe the geologicalconditions near the tunnel face and plan excavation work suitable for the geological conditions.
This section describes matters to be considered when conducting the pipe-jacking tunneling method.
> Inside the tunnel, be aware of the possibility of oxygen depletion and toxic gases. Carbon monoxide
and carbon dioxide are colorless, odorless, and difficult to predict from where they will originate.
Therefore, their presence or absence and concentration should be measured using a detector. Toxic gas
measurements must be taken prior to the beginning of each work shift to ensure safety. Recently, manytunnel construction sites install automatic measuring devices to continuously take measurements 24hours a day.
> If flammable gases are likely to be generated, fire is strictly prohibited.
> Pipe-jacking tunneling construction is often used for small-diameter sewer and water pipeline
construction, often with a diameter of 0.8 to 3 meters. In addition to the various temporary equipment
required for pipe-jacking tunneling, excavated earth and sand are carried out through the shafts. Takecare to avoid being caught-between, hit by flying/falling objects and falling from heights. Measures
such as prohibiting entry into the shaft during excavated soil removal are necessary.

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7.2 Safety Activities at Construction Sites
Construction sites are home to technicians from many job categories. Although the work performed
may seem different, experienced technicians are always mindful of some common matters. This
realizes high quality and safety. 7.2 describes common safety activities that all technicians shouldknow.

7.2.1 Cycle of Safety in Construction
By continuing the cycle of safety in construction, we can make worksites less prone to industrial
accidents. The cycle of safety in construction is to achieve the following aims.
a. Integrate construction procedures and safety.
b. Facilitate cooperation between the prime contractor and other related subcontractors.
c. Make safety and health activities a habit.
d. Be inventive in taking preemptive safety measures.
e. Inform everyone of construction and safety requirements.
Various safety activities should be incorporated into daily operations at construction sites. To
prevent industrial accidents, it is important to set up and continue the daily cycle of safety inconstruction.

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Cycle of Safety in Construction(1) Safety morning meeting before work
(To be participated by all prime contractors and related
subcontractors)(8) Safety check at theend of the workday(2) Safety meeting

Daily cycle ofsafety inconstruction(3) Inspection before
starting work

(7) Cleaning up yourassigned area(4) Guidance andsupervision during work(6) Meeting on safe
processes(5) Safety patrol(1) Safety morning meeting before work
All prime contractors and related subcontractors participate in the meeting, which includes apresentation on the results of the safety patrol conducted on the previous day by the worksite managers,
instructions regarding work safety for the day's work, and radio calisthenics.
(2) Safety meeting
Discussions will be led by the foremen, by job category. The training includes reviewing the resultsof the previous day's work process, hazard prediction (KY) activities related to today's work process,and newcomer education.
(3) Inspection before starting work
Before starting work, safety inspections are conducted, including inspections of the machines andtools used, checking the work content, etc.
(4) Guidance and supervision during work
Site supervisors (foreman, operations supervisor, etc.) provide guidance and supervision toworkers.
(5) Safety patrol
Safety patrols are conducted by the worksite manager and subcontractors, and instructions and197

guidance are given to each foreman, etc.
(6) Meeting on safe processes
The prime contractor and each specialty contractor will communicate and coordinate with eachother regarding work on the following day, and discuss work methods, etc.
(7) Cleaning up your assigned area
Every worker is to organize, tidy, clean, and sanitize the area he/she worked in.
(8) Safety check at the end of the workday
The prime contractor and the person in charge of specialty contractor will confirm measures toprevent fire, theft, public disaster, etc.

7.2.2 Safety and Health Education for Newcomers
Safety and health education for newcomers is provided when a business hires new workers. The
implementation of safety and health education for newcomers is required by the Ordinance on
Industrial Safety and Health.
[1] Matters related to danger or harmful effect of machines, etc., or raw materials, etc., and thoserelated to methods of handling thereof[2] Matters related to performance of safety devices, harmful substance control devices, or personal
protective equipment and matters related to methods of handling thereof[3] Matters related to operation procedures[4] Matters related to inspection at the time of commencement of work
[5] Matters related to the causes and prevention of diseases which workers are susceptible regarding
the work[6] Matters related to keeping the workplace in order and maintenance of its sanitary conditions[7] Matters related to emergency measures and evacuation at the time of an accident[8] Beyond what is set forth in each of the preceding item, matters necessary for maintaining safety
198and health related to the work

7.2.3 Newcomer education
A worker who newly enters a construction site is called a newcomer. Nearly half of all construction
site fatalities occur within one week of newly entering a site. For this reason, the Ministry of Health,Labour and Welfare has mandated newcomer education. The Guidelines for Construction Site Safety
Management by Master Employer defines the implementation standards as follows.
[Implementation of newcomer education]
In case of newly assigning any employees to work at a construction site, the related subcontractors
shall instruct their foremen, etc., to inform such workers of the following matters based on thecharacteristics of said construction site before they commence work at the site, and shall report theresults to the master employer.
[1] Conditions concerning locations where work is conducted by a mixed workforce that consistsof both the master employer's employees and the related subcontractors' employees[2] Locations that pose a danger to workers (dangerous and harmful places and no-entry zones)[3] Relationship between work processes conducted at mixed work sites[4] Evacuation methods[5] Command structure[6] Contents of the work involved and industrial accident prevention measures[7] Rules on safety and health[8] Plans that prescribe the basic policy and goals of safety and health management at theconstruction site and other basic industrial accident prevention measures
The above will be implemented as follows.
(1) Before work on the day the contractor first enters the site to begin work
The person in charge from the construction company (builder), the foreman, and the health and199

safety officer will conduct the training.
(2) Before work on the day a newcomer is added to the contractor's workforce
The foreman and the health and safety officer will conduct the training.
The training will take place in a conference or meeting room in the field office for about 30 minutes.

7.2.4 Safety Gear for Work
The photo below shows the safety gear for work. Full harness fall protection gear (1), helmet (2),hooks (3), and safety shoes (4) are the basic gear.

[Full-Harness gata tsuiraku boshiyo kigu] (full-harness fall protection gear) The full-harness fall
protection gear prevents falls. From January 2, 2022, it is mandatory to wear it if the height of theworking platform exceeds 6.75 m. However, in the construction industry where falling accidents occur
frequently, the use of full-harness fall protection gear is required even when working at heights
exceeding 5 m. However, falling accidents do occur for those wearing but not using the gear, so be
sure to use it.
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In addition, the following protective and safety equipment is used depending on the task.
[Hogo megane] (protective eyewear) These glasses are designed to protect the eyes from metal andwood dust, sparks, heat, smoke (including toxic gases), lasers and other harmful rays generated atconstruction sites and material processing sites. Select the best eyewear for your purpose.

[Hogo mask] (protective mask) A mask used to protect against dust and other debris. There aredisposable masks and those with replaceable filters. The Ministry of Health, Labour and Welfare(MHLW) sets the standard for masks. For example, inhaling dust from arc welding and rock cutting
operations over a long period of time can cause lung dysfunction (pneumoconiosis), so the use ofprotective masks is mandatory.
[Tebukuro] (gloves) Used to protect hands when performing machine/hand cut processing, painting
work, various types of installation work, and work involving chemical substances. However, gloves(work gloves) should not be used when using rotating blades such as circular saws, drilling machines,
chamfering machines, pipe threading machines, etc., because gloves (work gloves) can get entangled
in rotating blades and result in accidents.
[Shield-mentsuki helmet] (welding helmet) A helmet with a shield attached to it, protecting the entire
face. Mainly used for welding work.

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7.2.5 Prevention of Heat Strokes
Summer in Japan has many manatsubi (hot day) with temperatures exceeding 30°C and moshobi(extremely hot day) with temperatures exceeding 35°C. Work performed in hot temperatures can cause
the workers to have heat strokes. Heat stroke can cause
dizziness and fainting, muscle pain and stiffness, profuse
sweating, headache, mood discomfort, nausea, vomiting,fatigue, a sinking feeling, impaired consciousness,convulsions,

impairedlimb

movement,

high

body

temperature, and other symptoms that not only make it

WBGT measuring
instrument

impossible to continue working but can also cause death. The Japan Meteorological Agency calculates
and provides information on the predicted value of the Web Bulb Globe Temperature (WBGT) in eachregion. To reduce WBGT values, site managers install large fans, shading nets, dry mist systems, rest
areas, air conditioning equipment, water supply equipment, refrigerators, ice machines, drinking
watervending machines, etc. On extremely hot days, work start and end times may be moved up.
Workers should try to rest in a cool place, such as an air-conditioned rest area, during allotted breaktimes, and to drink water and consume salt before and after work. Also, wear breathable work clothes,safety vests that absorb heat easily, etc.

7.2.6 Marks Calling Attention to Work Safety
Marks with a green cross on a white background can be seen at various locations on the construction
site. This mark is called midorijuji (green cross) and is a symbol of safety and health. It is often
designed together with the words anzen daiichi (safety first) because safety is the first and mostimportant thing on a construction site. Helmets and kyukyubako (first aid kit) containing medicine andtools for first aid in case of injuries are also marked with the green cross. Sometimes the safety andhealth flag, combining the green cross with shirojuji (white cross) which represents eisei (health), is202

used.

Example of the green
cross
Examples of the safety andhealth flag

7.2.7 Understanding Human Error
Mistakes caused by humans are called human errors. Human errors occur because we are human.
This includes not only mistakes caused by carelessness, but also those caused by tenuki (cutting
corners), skipping procedures that should have not been skipped. To avoid getting involved in or
causing accidents on construction sites, it is important to be conscious of possible human errors. In
addition, human errors not only cause accidents involving people, but also affect the quality of thecompleted construction as well as cause delays in the process. It is said that there are 12 different
causes of human error.
(1) Cognitive errors
It is a human error caused by assumptions. For example, the assumption that “such and such
instructions will be given in this situation” can lead to misreading the actual instructions and cues
given.
(2) Lack of attention
It is a human error caused by lack of attention. Concentrating on one particular task can reduce
attention to one's surroundings and lead to accidents. For example, there are cases where a person isso focused on the work in front of him that he fails to notice the hole behind him and falls in.
(3) Attention lapse and diminished awareness203

Attention lapse and diminished awareness can occur especially when engaged in simple andrepetitive tasks. When simple tasks are repeatedly performed, workers stop thinking about those tasks
but instead perform them unconsciously.
(4) Inadequate experience/knowledge
It is a human error caused by lack of experience and ignorance. This can result in improper use oftools, incorrect understanding of the work process, or inability to anticipate accidents that may be
associated with the work. KY activities before commencing work are an opportunity for seasoned
technicians to share their experience in predicting hazards. Workers can learn what to look out for,even when engaging in the task for the first time.
(5) Complacency
Humans tend to gain confidence through familiarity and, as a result, tend to be less careful or skip
steps compared to when they were beginners at that task. Accidents are more likely to occur when
workers become complacent and relaxed. No matter how familiar you are with the work, be sure topractice safe conduct, inspect tools before you work, check your safety equipment, and wear and checkthe fit of your safety gear.
(6) Group errors
It is a human error that occurs in groups. For example, when it seems that meeting the construction
deadline is unlikely, it is easy to for the overall atmosphere to lean towards condoning unsafe conduct.
While it is important to meet construction deadlines, the safety of people is of primary concern. In
addition, if accidents occur due to unsafe conduct, they can cause delays in the construction schedule.
(7) Shortcuts and omissions
This is a human error caused by omitting necessary actions and procedures out of the desire to work
efficiently.
(8) Communication errors
This is a human error that occurs because the instructions are not clearly conveyed. Working without
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understanding the instructions can lead to accidents and construction delays.
(9) Behavior based on situational instinct
It is an action that we unintentionally take when we are in a certain situation. Especially when people
are focus on one point, they become oblivious to their surroundings. For example, when a person isabout to fall from a stepladder, he/she would throw his/her tools in order to hang onto the stepladder.
An accident occurs if those tools hit another worker.
(10) Panic
Sudden surprises or panic can easily lead to spontaneous unsafe behavior or giving inappropriate
directions.

(11) Decline in physical and mental functions
What was possible when younger may no longer be possible due to aging. In particular, reduced
function in the legs and hips and vision impairment are difficult to notice because they occur gradually.
It is important to be aware of this so that you do not try uncomfortable actions or postures.
(12) Fatigue
Accumulated fatigue reduces alertness, and this can lead to accidents. It is important to take goodcare of your health on a daily basis, including proper sleep and nutrition.

“Have a safe day!”

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