Side Friction 111 Austroads Rural road design, 8 th edition (2003) Values Source Reference 5204 Values from: “Rural road design, 8 th edition”, Austroads, 2003 Compiled reb Checked Not checked Table of side friction against speed (km/hr) Row 0 20 40 60 80 100 120 Notes a 0,35 0,23 0,17 0,14 0,12 0,09 AASHTO 2011 For sealed pavements: b 0.24 0.16 0.12 0.11 Desirable max c 0.33 0.26 0.16 0.11 Absolute max For unsealed pavements: d 0.20 0.12 0.08 0.07 Desirable max e 0.29 0.22 0.12 0.07 Absolute max Notes a. gives USA values from (ref.831). b, c. Values taken from table 9.1 for side friction factors for sealed pavements, where speed is the operating speed. d, e. Values for unsealed pavements taken from table 9.1 for side friction factors for sealed pavements, reduced by 0.04 as suggested in (para 9.4). Speed is shown as the operating speed Comment on the values quoted The source document is still (01/2023) referenced in the TRIB database, though I have not yet found it in the Austroads database. The values possibly represent side friction for wet road surfaces, for rural roads, are possibly applicable to all vehicle types, and related to operating speed. They also “assume construction and maintenance techniques will ensure an adequate factor of safety against skidding” ( para 9.4). They are based on the “point mass” model and possibly are based on side friction studies for cars. Notes from the text: