What kind of road ?

We want good roads everywhere but the Romans were perhaps the only civilisation who succeeded in having their cake and eating it. Their roads were robust and extensive but horribly expensive. Since then, to further entwine ourselves in culinary metaphors, we have had to put water in our wine. Western civilization had first of all to rediscover how to design and buildĀ  that were durable and economical. We are now faced with the problem of choosing the “good-enough road” (coined by the British child psychologist, D.W. Winicott to describe good parenting). In other words, the best for a given situation. If a road is under-designed, it will not fully exploit the benefits from improved service to users. Furthermore, it could be unstable and difficult to maintain under the combined assault of weather and traffic. If, on the other hand, it is over-designed, it will mop up funds that could be used for other roads. Also, it will be costly to maintain to a high standard. Finally, destruction of the natural environment will be more severe.

The level of service a road should provide must be determined pragmatically. Although road engineers have a natural inclination towards fixed national standards, these are only useful when they can be justified by the vehicle operating savings they induce, a function of traffic volume and extent of improvement. Many models, such as HDM-4, exist for such analyses. Their applicability becomes more and more questionable when vehicles are few and savings are small relative to the cost of the road. Attention must shift to networks rather than links and formal model-building should be replaced by stakeholder consultation.

The choice of road quality and the technical characteristics of the road which will best provide it is a compromise between technical and cost considerations, fuelled by a natural desire for speed and comfort, and severely restrained by willingness and capacity to pay. Engineers should determine what technical specification is most appropriate, based on user needs, terrain and weather (see also low-cost road surfaces). Environmental degradation must also be minimised by appropriate measures. Others should work with the stakeholders to determine the network they really want, once confronted with a full range of mobility options and their costs and armed with the information to make an informed choice amongst them.

:Powerpoint presentation: Construction techniques