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Questions and Answers
What is geometric design in the context of road construction?
What is a key difference in the traffic mix between developing and industrialized countries?
Why may high-speed roads be less necessary in developing countries?
What may not be economical in developing countries?
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What is the first step in developing geometric design standards for a road in a developing country?
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What stage of development are most developing countries usually at?
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Why are design standards currently in use often not suitable for developing countries?
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What is the main purpose of identifying the objective of a road project in a developing country?
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What is the primary purpose of access roads?
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What is the main difference between collector roads and access roads?
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What was the outcome of the study conducted by the Overseas Unit of Transport Research Laboratory (TRL formerly TRRL)?
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What is the primary function of arterial roads?
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What type of traffic is likely to dominate on access roads?
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What is the likely traffic flow level on collector roads?
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Why are geometric standards less important on collector roads?
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Where are the geometric design recommendations for rural access roads published?
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Study Notes
Geometric Design in Developing Countries
- Geometric design is the process of designing the layout of a road in the terrain to meet the needs of road users.
- In developing countries, the needs of road users differ from those in industrialized countries.
- Pedestrians, animal-drawn carts, and other non-motorized traffic are often important components of the traffic mix.
- Lorries and buses represent a large proportion of motorized traffic in developing countries.
Appropriate Geometric Standards
- Traffic volumes on rural roads in developing countries are relatively low.
- Providing a road with high geometric standards may not be economic due to low traffic volumes.
- The requirements for wide carriageways, flat gradients, and full overtaking sight distance may be inappropriate.
- Design levels of comfort used in industrialized countries may be a luxury that cannot be afforded in developing countries.
Objectives of Road Projects
- The objective of a road project should be identified in terms of three distinct stages of development:
- Stage 1: Provision of access
- Stage 2: Provision of additional capacity
- Stage 3: Increase of operational efficiency
- Developing countries are usually at stage 1 or 2, whereas design standards are often developed for stage 3.
Study on Geometric Design Standards
- A study by the Overseas Unit of Transport Research Laboratory (TRL) developed appropriate geometric design standards for use in developing countries.
- The study found that current standards are higher than justified from an economic or safety point of view.
- Geometric design recommendations were published in Overseas Road Note 6.
Classification of Rural Access Roads
- Rural access roads are classified into three groups:
- Access roads: lowest level in the network hierarchy, with low geometric standards and high non-motorized traffic.
- Collector roads: intermediate level, with intermediate traffic flows and trip lengths.
- Arterial roads: main routes connecting national and international centers, with high traffic flows and speeds.
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Description
This quiz covers the process of designing road layouts to meet the needs of road users, considering factors such as pedestrians, animal-drawn carts, and motorized traffic in developing countries.
