Page 39 - SAPEM-Chapter-10-2nd-edition-2014

South African Pavement Engineering Manual
Chapter 10: Pavement Design

• A Guide to Airfield Pavement Design and Evaluation. Third Edition. 2011. Construction Support Team,
Defence Estates, Ministry of Defence, United Kingdom. http://zemubarek.files.wordpress.com

The national guideline documents for design traffic estimation
are: References for Traffic
• TRH16: Traffic Loading for Pavement and Measurement and Estimation
Rehabilitation Design Good references for Traffic Measurement
• TMH3: Traffic Loading Load Surveys for Pavement and Estimation for Pavement Design are:
Design specifies the methods for axle load surveys.
• TRH16, Traffic Loading for Pavement
This section provides an overview of the design traffic estimation and Rehabilitation Design
process, loosely following TRH16. The components of the • TMH3, Traffic Loading Load Surveys
process are presented in the following sequence: for Pavement Design
• Concepts and terminology TRH4 and TRH12 also include detailed
• Traffic investigation for pavement design sections on handling traffic.
− General considerations
− Loading surveys All of these guidelines can be downloaded
• Design traffic calculations from www.nra.co.za.

4.1 Concepts and Terminology

The concepts and terminology associated with design traffic terminology, include:
• Legal axle loads
• Axle load histograms
• Standard axles and equivalent standard axles
TRH16 Based on 1989 Road Traffic Act
• E80s per heavy vehicle (E80/HV) The latest version of TRH16, published in 1991, is
• Traffic classes based on the 1989 Road Traffic Act. The
permissible axle load limits were increased in the
4.1.1 Legal Axle Loads 1996 Road Traffic Act. See Table 9 for the changes.

The permissible axle load limits, in terms of the average
static axle mass for different axle groups, are set by Regulations 234 to 240 of the Road Traffic Act of 1996, and
summarized in Table 9. Note that the latest version of TRH16 was published in 1991, and is based on the 1989 Act.

Table 9. Permissible Axle Loads
Wheel Permissible Static Mass (kg)
Vehicle Axle Group Configuration Pre-1996 Post-1996
1
2
Steering Single 7 700 7 700
Dual-wheel 8 200 9 000
Single
Single 7 700 8 000
Dual-wheel 16 400 18 000
Truck Tandem
Single 15 400 16 000

Dual-wheel 21 000 24 000

Tridem
Single 21 000 24 000

Steering Single 7 700 7 700
Bus
Single Dual-wheel 10 200 10 200

Note
1. Based on 1989 Act, and used in TRH16.
2. After the increase in legal axle loads in 1996.

Section 4: Design Traffic Estimation
Page 28