Wednesday, June 1, 2011

Landscape : Curbing The Curbs

Road curb or kerb, is the edge where a raised footpath, road median or road shoulder meets an unraised roadway.  It is typically made from concrete, asphalt or long stones.



Ideally …

Curbs are designed to guide water from melted snow and rain into storm drains.  It also keeps vehicles on the road.  Curbs also add to the aesthetic aspect of the road.

Since curbs add to the cost of a road, they are generally limited to urban and suburban areas, except where certain drainage conditions make them necessary.  However, curbs are not universally used, even in urban settings.



In reality …

Poorly maintained curbs often results in ponding of water.  Sand and dirt from vehicles, blades of grass leaves, debris and rubbish accumulate at drain.  After some time, the sand and debris become growing bed for weeds.  Soon the curb will be infested with weeds of all sizes !

Often after heavy downpour, surface rainwater find limited outlet to drain out of the road.  The curbs acts as a retention wall to keep the water in, while the scupper drains hardly suffice to drain the water in time ( as diagram below ).   It is not hard to find Malaysian roads flooded during heavy downpours, no thank to curbs !

Big puddles can be dangerous, as they can cause hydroplaning at higher speeds and loss of control of a vehicle.  At times, water can spray from tires onto following vehicles, causing poor visibility.  Also the unfortunate are pedestrians and motorcyclists who were splashed by hydroplaning.

Prolonged ponding due to blocking of water by curbs eventually leads to deterioration of asphalt concrete roads.  Over time, the damaged asphalt widened and deepened.  Potholes posses danger to motorists, especially motorcyclists, the least, damage the vehicle's tires and suspension system.

At the end of the day, all the shortcomings and damages translate into monetary losses.  Additional cost to construct the curbs, extra earth to level up, sweeping of sands, rubbish collection, weeding etc… all at our expense, the ratepayers.  For sure, someone is making a profit out of it.



To consider …

There are no doubts that curbs do serve their purpose, providing there are rightly located.  There are places for them, there are places not for them as well.

While it may be feasible to have curbs at pedestrian-heavy urban and housing estates, it may not necessary for highways, trunk roads and any other road with low pedestrian users. 


Cambered asphaltic concreted road, tufted soil/walkway should be leveled to allow smooth flow of water into the storm drains ( as diagram above ).  It may seems inconvenience for pedestrian as the water from the road, flowing pass the walkway.  But who would walk down less-travelled road during heavy downpour ?
  
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