Have you ever wondered why there are usually gaps on a road constructed on a bridge or an overpass?
Well, the gaps are referred to as expansion gaps. Just as the name suggests, the gaps are usually incorporated in the designs of a bridge and allow for the expansion and contraction of the road.
Usually, during the day, when it is sunny, parts of the bridge including the road will expand hence the space provides room for that.
Conversely, during a cold day, the road will contract, and that gap provides for that movement, ultimately safeguarding the entire structural integrity of the bridge.
On the other hand, engineers also install a joint in between the gaps to ensure that the expansion and contraction are done effectively.
"A gap is provided to allow for expansion and contraction due to temperature changes. It can be between a bridge girder and an abutment or between girders (iron or steel beam) that are not continuous.
"Expansion joint is a device installed at the expansion gap to ensure smooth expansion and contraction and to allow automobiles and other vehicles to run smoothly on the bridge. It is mainly made of steel or rubber," KeNHA explained in its bridge manual.
Maintainance
Additionally, KeNHA adds that the gaps have to be cleaned at all times to ensure the bridge is efficient.
This, therefore, requires its officials to conduct inspections regularly and check that there are no defects. The gaps often tend to be damaged given the force from the movements of the vehicles along the bridge.
"Poorly installed expansion joints and uneven settlement of any part of the bridge may cause level differences thus, water ponding," KeNHA expounded.
The guidelines also state that abnormalities within the gap have to be reported to engineers within 24 hours.
"Bridges inspected during dry weather could be revisited (as part of a safety inspection) during the next spell of rain to check whether expansion joints or drainage are leaking/blocked and adequate," the bridge manual added.
