The TRL Overseas Road Notes are a series of manuals and guidelines prepared for use byprofessionals working in the field of transport in developing countries and countries in transition. Theinformation contained within the ORNs represents the most up to date thinking on good engineering,transport safety, environmental mitigation and transport planning practice applicable in suchcountries.

The Overseas Road Note series dates from 1981. They are an ad hoc series covering a range oftopics reflecting the types of work being carried out at a particular time. They do not conform to any‘master plan’ and are therefore numbered simply according to order of publication. The exception inthe numbering system is Overseas Road Note 31. This originated in the TRL Road Note series asRN 31 and the number became firmly associated with the title. Thus, when the ORN series come intobeing and incorporated RN 31, the guide was allowed to retain its original number. Road Note 40,similarly, is an ‘honorary’ ORN that still carries its original RN number (but see below).

The Overseas Road Notes mostly remain current for many years and do not require regularupdating. However, they are revised when necessary. ORN 3 was recently revised and is nowpublished in its second edition. RN 40 is currently under revision and will shortly be reissued as ORN40.

The titles are as follows, but the titles can also be displayed by clicking on the ‘expand’ symbol nextto ‘Overseas Road Notes’ in the screen index.

ORN 1 Maintenance management for district engineersORN 2 Maintenance techniques for district engineersORN 3 A guide to surface dressing in tropical and sub-tropical countriesORN 4 Field survey techniques and analysis for urban bus operatorsORN 5 A guide to road project appraisalORN 6 A guide to geometric designORN 7 Volume 1. A guide to bridge inspection and data systems for district engineersORN 7 Volume 2. Bridge inspector’s handbookORN 8 A user’s manual for a program to analyse Dynamic Cone Penetrometer dataORN 9 A design manual for small bridgesORN 10 Costing road accidents in developing countriesORN 11 Urban road traffic surveysORN 12 Design guidelines for busway transitORN 13 Use of traffic signals in developing countriesORN 14 Hydrological design manual for slope stability in the tropicsORN 15 Guidelines for the design and operation of road management systemsORN 16 Principles of low cost road engineering in mountainous regionsORN 17 Road safety education in developing countries. Guidelines for good practice in primary

schoolsORN 18 A guide to the pavement evaluation and maintenance of bitumen-surfaced roads in tropical

and sub-tropical countriesORN 31 A guide to the structural design of bitumen-surfaced roads in tropical and sub-tropical

countriesORN 40 A guide to the measurement of axle loads in developing countries using a portable

weighbridge