Bridge maintenance

Maintenance and inspection

Maintenance is broken into two categories:

  • Routine maintenance– basic vegetation clearance is carried out one month before the inspection of the structure so a detailed inspection can be completed by our engineer.
  • General maintenance– maintenance needs are identified as part of the detailed inspection to ensure the structure remains ‘safe for use’ and ‘fit for purpose’.

Inspection

  • We inspect our bridges approximately every two years.
  • We investigate damage through vehicle collision, storms or other causes as soon as possible.
  • Public safety is maintained on weak bridges through temporary weight restrictions or other measures.
  • We prioritise principal road bridges when we carry out bridge strengthening work.
  • We may decide to permanently restrict the weight limit on substandard bridges on non-principal roads rather than strengthen them.
  • We consider each bridge on its merits before deciding what we will do, taking into account safety, economic and environmental factors.

Bridges

Bridges are arguably the most symbolic of man-made structures. Unique in their balance between structural and aesthetic concerns, they offer a physical representation of unity and optimism. It is no coincidence that the dawn of this millennium has been marked all over the world by the building of bridges as the world has stepped into new era. During this period, construction of monumental road or rail bridges has given way to a focus on the more intimate footbridge, reflecting the mounting concern for sustainability and the encouragement of healthier lifestyles.

“Of everything that man erects and builds in his urge for living nothing is in my eyes better and more valuable than bridges. They are more important than houses, more sacred than shrines. Belonging to everyone and being equal to everyone, useful, always built with a sense, on the spot where most human needs are crossing, they are more durable than other buildings and they do not serve for anything secret or bad.”

Ivo Andrić, 1961.a

Pavement

Asphalt concrete mixture: adequately designed mixture of mineral materials [crushed aggregate (gravel) and sand, with or without mineral dust] and bitumen, taken in specified proportions and mixed when hot.

Asphalt concrete — compacted asphalt concrete mixture.

A road pavement is a structure of superimposed layers of selected and processed materials that is placed on the basement soil or subgrade. The main structural function of a pavement is to support the wheel loads applied to the carriageway and distribute them to the underlying subgrade.

Earthworks

The types and physical and mechanical properties of the soils, which are designated for arranging of earth embankments and backfilling, shall be specified in the design as well as some special requirements to them and required compactness (compactness of dry soil or coefficient of compactness), borders of the parts of embankments, arranged from soils with different physical and mechanical properties.

Geogrid reinforcement

A geogrid is geosynthetic material used to reinforce soils and similar materials. Geogrids are commonly used to reinforce retaining walls, as well as subbases or subsoils below roads or structures. Soils pull apart under tension. Compared to soil, geogrids are strong in tension. This fact allows them to transfer forces to a larger area of soil than would otherwise be the case.[2]

Geogrids are commonly made of polymer materials, such as polyester, polyvinyl alcohol, polyethylene or polypropylene. They may be woven or knitted from yarns, heat-welded from strips of material, or produced by punching a regular pattern of holes in sheets of material, then stretched into a grid.

The development of methods of preparing relatively rigid polymeric materials by tensile drawing,[3] in a sense “cold working,” raised the possibility that such materials could be used in the reinforcement of soils for walls, steep slopes, roadway bases and foundation soils. The principal function of geogrids is for reinforcement. This area, as with many other geosynthetics, is very active, with a number of different products, materials, configurations, etc., making up today’s geogrid market. The key feature of all geogrids is that the openings between the adjacent sets of longitudinal and transverse ribs, called “apertures,” are large enough to allow for soil strike-through from one side of the geogrid to the other. The ribs of some geogrids are often quite stiff compared to the fibers of geotextiles. As discussed later, not only is rib strength important, but junction strength is also important. The reason for this is that in anchorage situations the soil strike-through within the apertures bears against the transverse ribs, which transmits the load to the longitudinal ribs via the junctions. The junctions are, of course, where the longitudinal and transverse ribs meet and are connected. They are sometimes called “nodes”.

Gutters

Noise screens