英文關鍵字
aerial
ballast
build
builder
building
concept
concrete
construct
construction
contractor
drone
employment
engineer
engineering
equipment
flying
helmet
industrial
industry
laying
machine
maintenance
metal
mine
mining
open
opencast
pit
rail
railroad
railway
repair
repairn
replacement
road
run
safety
sand
site
steel
technician
technology
track
tracks
train
transport
view
way
work
worker
workers