In Malaysia, all expressways are designed for a maximum speed of 120kph. The pavement width, the quality of road surface and the horizontal and vertical curves are factors that determine the design speed, a speed that will allow the drivers to drive safely in a consistent manner. For an example, the geometry of a horizontal curve is designed such that on negotiating the curve at the design speed, a vehicle will be able to go around it without going off on a tangent.

The speed limit is normally set below the design speed so as to provide an additional factor of safety for driving. And this is why the speed limit of our expressways has been originally set at 110kph. However, if the speed limit is to be raised while maintaining the same factor of safety, the expressways need to be modified especially at some critical horizontal and vertical curves. These can be identified for improvements if a road safety audit has been carried out.

The design of highways would have incorporated sufficient safety roadside furnishing to minimize damage and increase the chances of survival in case of accidents. These include adequate road safety zones, roadside table or emergency lane and crash cushions. To raise the speed limit, these have to be upgraded.

But our expressways have more roadside furnishing than what they have been designed for. We find teak and other trees planted and huge advertising boards and signposts with solid pillars erected by the side of the expressways without any crash barriers. Even in the median, trees and palms are grown. In the event of a crash, these will invariably increase damage and decrease the chances of survival.

The pavement of highways, i.e. its structure and thickness is designed to withstand a certain amount of axle load of trucks and lorries. But one can easily notice that along many stretches of our expressways, the ridability or the quality of road surface of the slow lane is not as good as that of the fast lane. This is due primarily to overloading of heavy vehicles on the slow lane causing the pavement to settle and crack. Because of this, many cars try to avoid the slow lane and hog the fast lane even if they are not overtaking.

Therefore, unless the existing expressways have been upgraded to raise the speed limit above the design capacity, it is indeed misleading to say that we have better highways now to justify for the increase.

But upgrading the existing expressways is only one aspect to be considered before raising the speed limit. Another equally important aspect is the engine capacity of cars and the standard of their maintenance.

No doubt modern cars are built with better technology and engineering design, but we still have many slow and antiquated bone-shakers on the road. On top of that we allow over-loaded trucks and lorries and lowest-capacity motorcycles to crawl on our expressways.

Raising the speed limit for cars and allowing slow-moving vehicles to be on the road effectively increases the speed difference between the fastest vehicle and the slowest. The increase in this speed differential will invariably increase the risk of injury in an accident. It is said that if the speed differential exceeds 40kph, the chances of one getting out of the accident without major injury are slim.

True, most accidents happen on state and trunk roads and not on highways and expressways. Current statistics show that only about 6% of deaths happen on expressways. But, by just raising the speed limit without taking other necessary corrective measures will not only increase the number of accidents but also will increase damage and in number of fatalities.

Only lately the Works Minister suggested that the speed limit for smaller cars such as Kancil should not be raised. All these talks indicate that the government has not given enough thought to this subject of raising the speed limit and its contingent ramifications. Just based on a mere survey which indicated that 87% of car owners supported the increase is a grossly irrelevant justification. A lot has to be done before the increase can be implemented to contain the number of road accidents and fatalities.