Page 68 - SAPEM-Chapter-10-2nd-edition-2014

South African Pavement Engineering Manual
Chapter 10: Pavement Design

• Drainage provision or improvement of existing drainage
facilities
Uniform Sections
The main components of a rehabilitation investigation are:
• Initial assessment A uniform section is a section of road for
which the condition and structure are
• Detailed assessment similar. Appropriate rehabilitation options
• Environmental and practical design considerations are therefore suitable for the whole
section. The final design selected is used
The condition assessment, which is part of the initial and detailed on the full uniform section.
assessments, forms the foundation of the rehabilitation
investigation and design process. The aim is to determine uniform Uniform sections should not be so short as
pavement sections at the project level that are similar in condition to introduce construction problems.
and require similar structural or functional improvement. This is
done during the initial assessment. The cause and mechanism of distress on each uniform section is identified
during the detailed assessment.

The nature and detail of the condition assessment should take the following into consideration:
• Road category
• Available resources
• Nature, quantity and quality of data available at the onset of the investigation

The initial and detailed assessments are integral to the condition assessment, but are treated separately for ease of
discussion. They are also discussed in Chapter 6.

5.1.2.1 Initial Assessment
The objectives of the initial assessment are:
• Record and process data into a format that may be readily used Condition Assessment
during subsequent detailed investigations. These chapters discuss various
• Benchmark the pavement condition against standard conditions. elements of the condition
The condition limits given in Section 7.5 for deflections, and Chapter assessment of roads, including the
6: 7 and TRH12 for all distress types. devices used for measurement:
• Divide the road into uniform sections that require different • Chapter 6: Road Prism and
rehabilitation actions. See Chapter 6: 7.2.2.1 for more details. Pavement Investigation,
• Recommend appropriate measures for sections that obviously only Section 5 and 7
exhibit surfacing or localized distress. • Chapter 14, Post-Construction,
• Identify and recommend appropriate tests for the sections that need Section 3
detailed investigation to determine the cause and mechanism of
pavement distress.

The components of the initial assessment include the gathering of information, data processing and condition
assessment, and an initial assessment of the structural capacity of the uniform sections.

(i) Information Gathering
The information gathered during the initial assessment is mostly obtained from three sources:
• Preliminary investigation: The preliminary investigation relies mostly on available data such as construction
and pavement management system (PMS) data and a preliminary site visit. PMS data typically includes historic
traffic data, surveillance measurements, and maintenance and rehabilitation records. Often the PMS surveillance
measurements are sufficient, and only supplemental surveys are
required. The photo and video records in most PMS systems
provide valuable information, which should be viewed and can
be checked during the detailed visual inspection. The Know Your Traffic Data!
preliminary investigation is followed by a detailed visual distress When calculating design traffic from
survey and non-destructive surveillance measurements. available or measured traffic data, it is
• Detailed visual inspection of the road: Photographs are essential to know what the data is for.
invaluable to the visual inspection process and create a For example, if it’s for the entire road,
permanent record of the visual distress. Photographs should be directional and lane distributions need to
taken of the distress on the road, and the condition of road be applied.

Section 5: Pavement Investigation and Design Process
Page 57