Other Types of Road Construction

Roads with continuous pavement are much appreciated for such leisure activities as bicycling, jogging, or rollerskating, although avoided by other users such as ramblers. In vulnerable areas, objections often are raised to pavement for reasons that have to do with the landscape. Many spur roads are built in such areas, a variation that has proven its worth. The tracks for vehicles usually are made of concrete, with grass in between

Figure 3.15. Nomogram for the construction of roads with low volume of traffic and flexible road body (p = 1.5). Source: [27].

Figure 3.16. Example of calculation of the road body. Source: [24].

Figure 3.16. Example of calculation of the road body. Source: [24].

and on the verges (Fig. 3.18). This reduces the total extent of the sealed area, and the amount of surface water runoff, without having too much effect on the practicability. The visual impact is also better. In some countries, it has long been the custom to use hot-mix bearing beds for this application. For purely agricultural roads with steep gradients and involving a real danger of erosion, the tracks are made of permeable concrete sections (e.g., checker brick). Even with roads of this type, it is important to consider the question of drainage. It goes without saying that spur roads are suitable only for single-lane roads with little traffic. Performing ecological impact studies are important as well [28].

3.4.9 Road Safety

By virtue of their geometry, minor rural roads are suited for speeds of 30-40 kph. It must be clear, therefore, that they do not meet the same safety standards as highperformance roads. Even so, it may become necessary to take certain measures in the

I

]

(

Gradient

Dirt road 0 12 3

Traffic

Gradient

few

: Farm road

medium

: Feeder road

large

: Connecting road

few

: Arid regions

medium

: Central plateau

large

: Mountainous regions,

Thunderstorms

small

: < 4 %

medium

: 4-0 %

large

: > 8 %

small

: Forest

large

: Open space

Bituminous pavement or cement concrete pavement

Dirt road 0 12 3

Bituminous pavement or cement concrete pavement

Erosion class

O"

Example; 7 points; farm road in a mountain area

Figure 3.17. Criteria for determining the type of pavement. Source: [24].

event of mixed usage (by cars, pedestrians, bicyclists, in-line skaters, etc.), in relation to dangerous sections (sharp corners, slopes that are steep or ill-adapted to driving, danger of rockslides, avalanches, floods), or temporary peaks in the amount of traffic (weekends, special events). The appropriate solution in each case can be difficult to assess. The measures referred to include

• signs indicating use of the road by agricultural or forestry traffic, livestock, bicyclists, or pedestrians and alerting users to the danger of falling rocks, etc.;

• passing places within easy viewing range along one-track through roads, and along other simple roads at distances of 150-250 m (within earshot), light signal controls for one-track tunnels and long bridges;

• protective barriers along dangerous roads;

• Rockslide safety measures (netting, blasting at the time of construction, clearing away of rocks);

• avalanche and flood warning systems.

Galleries to protect against rockslides or avalanches are, in most cases, out of the question for cost reasons. To guard against such dangers, measures to combat the causes, such as afforestation or timbering in areas where cracks are a problem, may be more appropriate.

Figure 3.18. Standard cross section of a concrete spur road.
Growing Soilless

Growing Soilless

This is an easy-to-follow, step-by-step guide to growing organic, healthy vegetable, herbs and house plants without soil. Clearly illustrated with black and white line drawings, the book covers every aspect of home hydroponic gardening.

Get My Free Ebook


Post a comment