3. Urban Road Construction and Reconstruction
3.1 Introduction
Techniques for urban roads are essentially similar
to those for rural roads, but there are some additional unique factors.
3.2 Public Utilities
Road reserve the normal location for many public utility
services e.g. water mains, electricity supply lines, telephone lines, gas
mains, etc. Most services (except sewers) placed under footpath areas so
that maintenance and repair can be carried out without disruption to traffic.
3.3 Provision of Materials
Stockpiling of materials usually more dificult in an
urban environment, so greater coordination of material requirements required
than in a rural setting.
3.4 Setting Out
Survey pegs more likely to disturbance from vehicles
and humans than in a rural environment. Recovery pegs are usually located
near property boundaries to minimise disturbance.
3.5 Plant
The work area in urban road reconstruction is often
relatively small and so careful plant selection is required. The type and
size of plant may also be limited by the amount of work that can be opened
up and backfilled in one day.
Plant varies from job to job, but for reconstruction
work typically consists of:
- Small dozer - for ripping and dozing.
- Loader and trucks - for removal of spoil and
delivery of pavement materials.
- Grader - for trimming and spreading.
- Rollers - for compaction.
3.6 Drainage During Construction
Drainage of work during construction requires careful
attention at all times. Work should be carried out so that there will be no
ponding of water, should storms occur. The job should be checked at the end
of each day's work to ensure that any overnight rain will be carried away
from the work are without damage to the work.
In urban work, the permanent underground stormwater
drainage system will be used as far as practicable for site drainage. The
construction of storwater drains should, when feasible,be the first work carried
out. It will be normal to commence the drainage work at the lowest point
and work upstream.
Flooding of the job or saturation of loose material
can cause long, costly delays and can reduce the soundness of work.
3.7 Rock Excavation
In urban work rock excavation poses more difficulties
than it does in a rural environment. Special care must be taken to restrict
explosive charges to a size which will cause no damage to buildings by ground
vibration. Care must also be taken to prevent any flying rock from blasting
operations. Use of effective matting is essential in this regard.
Inspection of all buildings prior to any blasting
is essential. Note should be made of any existing cracks or defects so as
to minimise subsequent claims for damages.
A similar type of problem may arise with the use
of vibrating rollers in urban areas and care must be taken to minimise damage
claims.
Page last modified 25 June 2002.