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Chapter 7: Secondary and tertiary roads

机译：第七章：第二和第三条道路

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Secondary and tertiary roads cater mainly for intra-provincial travel and are, in the main, the responsibility of the provincial government. In the earlier part of the century the four then existing provinces concentrated their efforts on 'getting out of the mud' with a blacktopping programme for the more heavily trafficked roads and a gravelling programme for lesser trafficked (but greater in total length) roads. This policy of differentiating in the improvement process between the different levels of road based on traffic volumes contrasted with Australian practice at the time of opting for a greater length of blacktopping, but with lighter pavements. In hindsight this turned out to be a costly approach in the long term, since the Australian road authorities were later faced with major road repair costs as road traffic grew. The gravelling improvement approach used by the provinces consisted in the main of providing the road with an adequately wide eight inches thick gravel surface, and cutting mitre drains to drain surface water off the road where necessary. Water flow across the road was eliminated by the provision of pipe culverts. River crossings were generally of the low-level submersible type where traffic could not pass in times of flooding - mostly no more than 10% of the time. The type and quality of the material used for gravel surfacing were of prime importance in its eventual riding qualities, both in dry and wet conditions. During the late 1950s and early 1960s the then Natal Provincial Roads Department carried out research to determine the necessary qualities in the choice of gravel for road surfaces, and devised a handbook for the choice of materials for this purpose. This work was later further developed at the then National Institute for Road Research (NIRR)of the CSIR.
机译：二级和三级公路主要用于省内旅行，主要由省政府负责。在本世纪初，当时的四个省份集中精力“摆脱泥泞”，针对交通更繁忙的道路实施了柏油封顶计划，针对交通流量较小（但总长度较大）的道路实施了涂蜡制计划。这种基于交通量在不同等级的道路之间进行区分的改进政策与澳大利亚在选择更长的柏油路段长度但人行道较轻时的做法形成鲜明对比。事后看来，从长远来看，这是一种昂贵的方法，因为随着道路交通的增长，澳大利亚道路当局后来面临着重大的道路维修费用。各省使用的砾石改良方法主要包括为道路提供足够宽的八英寸厚的砾石面，并在必要时切割斜切排水装置以将地表水排出道路。设置管道涵管消除了整个道路上的水流。河流过境通常属于低层潜水式，在洪水泛滥时交通无法通过-大多数时间不超过10％。不论是在干燥还是潮湿的条件下，用于砾石铺面的材料的类型和质量对最终的骑乘品质至关重要。在1950年代末和1960年代初，当时的纳塔尔省道路部门进行了研究，以确定在选择路面砾石时必须具备的质量，并为此目的设计了手册来选择材料。这项工作后来在当时的CSIR国家道路研究所（NIRR）进一步开发。

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  • 来源
    《Civil Engineering》 |2014年第7期|68-70|共3页
  • 作者

    Malcolm Mitchell;

  • 作者单位

    SAICE;

  • 收录信息 美国《工程索引》(EI);
  • 原文格式 PDF
  • 正文语种 eng
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