Which TMH manual do I need? A map of South African road manuals by job

Which TMH manual you need depends on the job: TMH 9 for visual condition ratings, TMH 13 for automated measurement, TMH 18 for data exchange files and TMH 22 for road asset management. TMH (Technical Methods for Highways) is the South African road manual series now compiled under COTO, the Committee of Transport Officials. TMH 9 and TMH 13 are Committee Draft Final documents (May 2016), TMH 18 is Draft Version 4 (October 2014) or Committee Draft 5.0 (February 2016), and TMH 22 is a Draft (March 2013). This guide maps each manual to its job and to the manual that takes over; it gives no procedures or thresholds.

Key facts

• TMH 9, TMH 13, TMH 18 and TMH 22 are South African road manuals compiled under COTO (Committee of Transport Officials) for visual assessment, measurement, data exchange and asset management.
• The South African road manuals TMH 9 and TMH 13 are Committee Draft Final documents dated May 2016, and TMH 9 states that Committee Drafts have no legal standing.
• SAPEM, the South African Pavement Engineering Manual (2nd edition, October 2014), is a 14-chapter guideline from SANRAL, the South African National Roads Agency, and states it is not a specification.
• TMH 22, the road asset management manual, states it does not cover project-level activities, including design, so candidate projects pass to TRH 12 and to SAPEM for investigation and design.
• TMH 18, the road data exchange manual, exists as Draft Version 4 (October 2014) and Committee Draft 5.0 (February 2016), which differ, for example, in the geometry file format.
• In the South African road manuals, TMH 12 and TRH 12, TMH 22 and TRH 22, and TMH 24 and TRH 24 are different documents that share a number.

The concept map

The connections in text

1. Road class (TRH 26) → Road register (TMH 22): class recorded
2. Road register (TMH 22) → Visual ratings (TMH 9): segments and km
3. Road register (TMH 22) → Automated measurements (TMH 13): km referencing
4. Visual ratings (TMH 9) → Exchange files (TMH 18): ratings to files
5. Automated measurements (TMH 13) → Exchange files (TMH 18): measurements to files
6. Exchange files (TMH 18) → Indices and needs (TMH 22): files to database
7. Indices and needs (TMH 22) → Investigation: TRH 12, SAPEM Ch 6 (TRH 12): candidate project
8. Investigation: TRH 12, SAPEM Ch 6 (TRH 12) → Design: SAPEM Ch 10, TRH 4 (SAPEM): investigation to design
9. Road class (TRH 26) → Design: SAPEM Ch 10, TRH 4 (SAPEM): class to category
10. Design: SAPEM Ch 10, TRH 4 (SAPEM) → Build: SAPEM Ch 11-13, COTO specs (SAPEM): design to tender
11. Build: SAPEM Ch 11-13, COTO specs (SAPEM) → Automated measurements (TMH 13): acceptance tests
12. Build: SAPEM Ch 11-13, COTO specs (SAPEM) → Road register (TMH 22): year built
13. Build: SAPEM Ch 11-13, COTO specs (SAPEM) → Monitoring: SAPEM Ch 14 (SAPEM): completed works
14. Monitoring: SAPEM Ch 14 (SAPEM) → Visual ratings (TMH 9): visual monitoring
15. Monitoring: SAPEM Ch 14 (SAPEM) → Automated measurements (TMH 13): surveillance measurements
16. Indices and needs (TMH 22) → Valuation: TMH 22 Part C, GRAP 17 (TMH 22): condition to value

What are TMH, TRH and SAPEM?

TMH (Technical Methods for Highways) is the South African road manual series that prescribes methods or gives guidelines for highway engineering work, such as visual assessment of pavements, automated measurement and asset management (COTO, 2016b)(COTO, 2014)(COTO, 2013). TRH (Technical Recommendations for Highways) is the companion South African road manual series that describes recommended practice, for example TRH 12 for flexible pavement rehabilitation, TRH 4 for structural design and TRH 26 for road classification (COTO, 2012). SAPEM (the South African Pavement Engineering Manual) is a 14-chapter guideline from SANRAL, the South African National Roads Agency, and it does not replace the manuals it cites (SANRAL, 2014a).

The Department of Transport's roads catalogue lists TMH and TRH documents but carries no SAPEM chapters (Department of Transport, n.d.); SANRAL publishes those separately (SANRAL, 2014a). The front matter of TMH 9, the visual assessment manual, states that Committee Drafts have no legal standing and that Draft Standards carry full legal standing during a two-year implementation period (COTO, 2016b). SAPEM calls itself a best practice guideline, not a specification (SANRAL, 2014a). Every manual below therefore carries its cover edition and status; the client's terms of reference name the edition that applies.

Which TMH, TRH or SAPEM manual fits each of the nine jobs?

Road asset work repeats nine jobs: register, collect, standardise, decide, investigate, design, build, monitor and value. The table names the manual to open first, its edition and status, and where the work passes next.

Narrated film · 1:37

Which TMH manual do I need?

Two maps trace the work from the road register to a candidate project and on to monitoring; the film then shows where each manual stops, which TMH and TRH numbers repeat, and the edition and status on each cover.

Read the film transcript

Ask which TMH manual you need, and the answer starts with the job, not the number. TMH, Technical Methods for Highways, is the South African road manual series now compiled under COTO, the Committee of Transport Officials. TRH, Technical Recommendations for Highways, is the companion series, and SAPEM, the South African Pavement Engineering Manual, is a SANRAL guideline. Road asset work repeats nine jobs: register, collect, standardise, decide, investigate, design, build, monitor and value. Register the road and its TRH 26 class under TMH 22, collect with TMH 9 or TMH 13, then standardise under TMH 18. TMH 22 turns the files into indices and needs, and its Part C covers value. Candidate projects pass to TRH 12 and SAPEM Chapter 6 for investigation. SAPEM Chapter 10 and TRH 4 cover design, Chapters 11 to 13 cover building, and Chapter 14 covers monitoring. Each manual stops where its scope ends: TMH 9 at ratings, TMH 18 at the file, TMH 22 at the network. Numbers repeat: TRH 12 is pavement rehabilitation, but TMH 12 was an earlier visual manual that TMH 9 Part E withdrew. Each cover names an edition and status, and TMH 9 says a Committee Draft has no legal standing. Choose the manual by the deliverable, read its edition on the cover, and note which manual takes over. Next, open TMH 22 for the register and indices, then SAPEM for investigation and design.

Job	Typical deliverable	Open first (edition and status)	Work passes to
Register	Road register with class and location referencing	TMH 22 Part B (Draft, March 2013) (COTO, 2013); TRH 26 (Version 1.0, August 2012) (COTO, 2012)	TMH 9 and TMH 13
Collect	Visual assessment programme or automated condition survey	TMH 9 Parts A to E (COTO, 2016b); TMH 13 Parts A to G (COTO, 2016d) (both Committee Draft Final, May 2016)	TMH 18
Standardise	Data submission to the road authority	TMH 18 (Draft Version 4, October 2014, or Committee Draft 5.0, February 2016) (COTO, 2014)(COTO, 2016i)	TMH 22 Part D
Decide	Condition indices, needs and candidate projects	TMH 22 Parts E to G (Draft, March 2013) (COTO, 2013)	TRH 12
Investigate	Project investigation plan and report	TRH 12 (Draft, 1997) (Department of Transport, 1997); SAPEM Chapter 6 (2nd edition, October 2014) (SANRAL, 2014k)	SAPEM Chapter 10 and TRH 4
Design	Pavement design report	SAPEM Chapter 10 (2nd edition, October 2014) (SANRAL, 2014b); TRH 4 (Draft, 1996) (CSRA, 1996); TRH 16 (Draft, December 1991) (CSRA, 1991) for traffic loading	SAPEM Chapter 11
Build	Tender documents, construction records, acceptance	SAPEM Chapters 11 to 13 (2nd edition) (SANRAL, 2014a); COTO Standard Specifications (Draft Standard, October 2020) (COTO, 2020a)	TMH 22 Part B and TMH 13
Monitor	Condition monitoring in service	SAPEM Chapter 14 (2nd edition) (SANRAL, 2014f)	TMH 9 and TMH 13
Value	Current and depreciated replacement cost	TMH 22 Part C (COTO, 2013); GRAP 17 (Standard of GRAP, issued February 2010) (ASB, 2010)	The entity's accounting policy

Last reviewed on 21 October 2026 against the editions named in this table.

TMH 22 appears in several rows because its Parts A to J run from inventory to asset management plans, and it says the detail of condition assessment lives in TMH 9, TMH 13 and TMH 19 (COTO, 2013); TMH 9 and TMH 13 call themselves its companions (COTO, 2016b)(COTO, 2016d).

Which part of TMH 9, TMH 13, TMH 18, TMH 22 or SAPEM do I open first?

Open Part A of TMH 9 or TMH 13 first, then the part for your pavement type or measurement.

• TMH 9: Part A first, for distress attributes, segment lengths, assessor accreditation and the quality management plan, then Part B (flexible), C (concrete), D (block) or E (unpaved) for the pavement type (COTO, 2016b).
• TMH 13: Part A first, for measurement concepts and survey planning, then Part B (positioning), C (roughness), D (rutting), E (skid resistance and texture), F (surface deflection) or G (imaging) (COTO, 2016d).
• TMH 18: Section 1 for the global file format, Sections 2 to 4 for the network, classification, lane and traffic files, then Section 5 for the condition data files (COTO, 2014)(COTO, 2016i).
• TMH 22: Part B for the register and road classes, Part D for condition data, Parts E to G for indices and needs, Part C for valuation (COTO, 2013).
• SAPEM: Chapter 1 for the chapter map, then Chapter 6 for investigation, Chapter 10 for design and Chapter 14 for post-construction (SANRAL, 2014a).

Where does each road manual stop, and which manual takes over?

• TMH 9 stops at ratings. It records distress type, degree, extent and, where applicable, spacing or activity on a segment, and gives no index formula (COTO, 2016b). TMH 22 Part E describes the indices computed from those ratings, including the visual condition index (VCI) for flexible paved roads in Appendix J-6 (COTO, 2013).
• TMH 13 frames the survey but is not its specification. It helps a road authority plan, execute and control automated surveys of roughness, rutting, skid resistance, texture, deflection and imaging, and states that it is not a complete specification (COTO, 2016d). The COTO Standard Specifications refer to TMH 13 for pavement tests in clause A20.1.5.5 (COTO, 2020a).
• TMH 18 fixes the file, not the method. It specifies how network, classification, lane, traffic, visual condition, instrument and deflection data are submitted, points to TMH 9 for the visual condition detail and does not say how to measure or rate (COTO, 2014)(COTO, 2016i). The two versions differ, for example in the geometry format, so name Draft Version 4 or Committee Draft 5.0 on every file.
• TMH 22 stops at the network. It states that project-level activities, including design, are not covered by it (COTO, 2013). Candidate projects pass to TRH 12; the insight on network screening and project investigation explains why the two levels answer different questions.
• TRH 12 leaves the detailed methods elsewhere. It sets out a systematic approach from investigation to economic appraisal and says it does not cover in detail the design methods for pavement evaluation and rehabilitation (Department of Transport, 1997). SAPEM Chapter 14 points to TRH 12 and to SAPEM Chapters 7 and 10 for the rehabilitation design process (SANRAL, 2014f).
• TRH 4 and SAPEM Chapter 10 share the design job. TRH 4 sets out structural design of flexible pavements for interurban and rural roads, using four road categories and a design catalogue (CSRA, 1996). SAPEM Chapter 10 covers design traffic, the investigation and design process and structural capacity estimation (SANRAL, 2014a)(SANRAL, 2014b). The client's terms of reference decide which governs a project.
• TMH 22 Part C stops at depreciated replacement cost. GRAP 17 (the Standard of Generally Recognised Accounting Practice on property, plant and equipment) lists road networks among infrastructure assets (ASB, 2010); accounting policy belongs to the entity and its auditor.

How does one flagged road segment move through the manuals?

A flagged segment passes from the network manuals to the investigation manuals and then to the design manuals. The synthetic example below traces one; every value is invented. A 12.0 km length of Road S1 runs from chainage (distance along the road from its start) 14.0 km to 26.0 km and is rated in six equal assessment segments of 2.0 km (a real survey takes its segment length from TMH 9 Part A Section A.3, not from this example). Numbered from chainage 14.0 km, segment 3 spans 18.0 km to 20.0 km, and network screening flags it.

The flag rests on TMH 9 ratings, delivered as TMH 18 files (Committee Draft 5.0 in this example) and held in a register that groups roads by TRH 26 class (COTO, 2013). TMH 22 Parts E to G turn the ratings into an index and a candidate project. The candidate then moves to TRH 12 and to SAPEM Chapter 6, which describes how the investigation determines uniform sections, the lengths into which a road is divided for evaluation (SANRAL, 2014k). TMH 9 Part A states that its segments are not meant to identify uniform sections, so the two need not match (COTO, 2016b). For design, SAPEM Chapter 1 Table 1 maps the TRH 26 class to a TRH 4 road category (SANRAL, 2014a), and TRH 16 gives the method for traffic loading (CSRA, 1991). Check value: 6 segments × 2.0 km = 12.0 km, and segment 3 starts at 14.0 km + 2 × 2.0 km = 18.0 km.

Which TMH and TRH manual numbers are confused with each other?

Several TMH and TRH numbers repeat, and each pair is a different document.

• TMH 12 and TRH 12. TRH 12 (Draft, 1997) is the flexible pavement rehabilitation manual (Department of Transport, 1997). TMH 9 Part E (Committee Draft Final, May 2016) withdraws the previous Draft TMH 12, an earlier visual manual (COTO, 2016k).
• TMH 22 and TRH 22. Draft TRH 22 (1994) describes pavement management systems (CSRA, 1994). Draft TMH 22 (March 2013) is the road asset management manual, and it does not state that it replaces TRH 22 (COTO, 2013).
• TMH 24 and TRH 24. TMH 24 (Draft Standard, version 1.0, July 2025) covers road restraint systems (RTMC and COTO, 2025). TRH 24 (Draft Standard, October 2024) covers upgrading unpaved roads (COTO, 2024).
• Neighbours outside pavement condition. TMH 19 (Draft Standard, August 2020) covers visual assessment of road structures such as bridges and culverts (COTO, 2020b). TMH 11 (Standard Survey Methods, Version 3.0, April 2017) covers land surveying, so it is not a condition survey manual (COTO, 2017).
• Unpaved roads. Rate unpaved roads with TMH 9 Part E (COTO, 2016k). TRH 20 (Draft Version 1.5, April 2009) covers design, construction and maintenance of unsealed roads (Department of Transport, 2009).

What records should I keep when work moves between manuals?

Keep these records with every deliverable passing from one manual to the next:

• the manual number, part, edition and status, copied from the cover, for example "TMH 9 Part B, Committee Draft Final, May 2016";
• the TMH 18 version used for each file, Draft Version 4 or Committee Draft 5.0;
• the road identifier, start and end chainage and direction of travel for each record, so that segments, instrument records and register entries describe the same piece of road;
• the TRH 26 class recorded in the register, because it feeds the TRH 4 category;
• the client instruction naming the edition and the specification basis.

The insight on survey acceptance evidence explains how such records show why data are usable.

Frequently asked

Which TMH manual do I need to rate road condition?

Open TMH 9 (Committee Draft Final, May 2016), the South African visual assessment manual for road pavements, starting at Part A, to rate pavement distress visually. Open TMH 13 Parts A to G for automated measurement of roughness, rutting, skid resistance, texture, deflection or imaging. TMH (Technical Methods for Highways) manuals are now compiled under COTO, the Committee of Transport Officials, and TMH 22 (Draft, March 2013) Part E describes the condition indices computed from visual ratings.

What is the difference between TMH, TRH and SAPEM?

TMH (Technical Methods for Highways) manuals prescribe methods or give guidelines, for example for visual assessment and data exchange. TRH (Technical Recommendations for Highways) manuals describe recommended practice. SAPEM, the South African Pavement Engineering Manual, is a 14-chapter guideline from SANRAL, the South African National Roads Agency. Recent documents in both series are compiled under COTO, the Committee of Transport Officials; older TRH covers name the Committee of State Road Authorities or the Committee of Land Transport Officials.

Where is SAPEM in the list of South African road manuals?

SAPEM, the South African Pavement Engineering Manual, sits outside the TMH and TRH numbering. SANRAL, the South African National Roads Agency, publishes its 14 chapters (2nd edition, October 2014) as separate files, and the Department of Transport's roads catalogue page lists TMH and TRH documents but no SAPEM chapters. SAPEM calls itself a best practice guideline, not a specification, and says it does not replace the manuals it cites.

Which manual receives the work after a TMH 22 network assessment?

TMH 22 (Draft, March 2013), the South African road asset management manual, states that project-level activities, including design, are not covered by it. A project flagged at network level passes to TRH 12 (Draft, 1997) for rehabilitation investigation and design, and to SAPEM (the South African Pavement Engineering Manual) Chapter 6 for pavement investigation, then to SAPEM Chapter 10 and TRH 4 (Draft, 1996) for pavement design.

Is TMH 12 the same as TRH 12?

TMH 12 and TRH 12 are different South African road manuals. TRH 12 (Draft, 1997) is the flexible pavement rehabilitation investigation and design manual. TMH 12 was an earlier visual assessment manual for unsealed roads, and TMH 9 Part E (Committee Draft Final, May 2016) withdraws the previous Draft TMH 12. The same caution applies to TMH 22 and TRH 22, and to TMH 24 and TRH 24.

Do TMH, TRH and SAPEM documents carry legal standing?

The legal standing of a South African road manual depends on the status printed on its cover. The front matter of TMH 9 states that Committee Drafts have no legal standing and that Draft Standards carry full legal standing during a two-year implementation period. SAPEM (the South African Pavement Engineering Manual) describes itself as a guideline, not a specification. Check the status on each cover and the edition named in the client's terms of reference.

Where this connects

TMH 22 explained walks through its Parts A to J, SAPEM explained covers its 14 chapters, and pavement management steps follows one piece of work around the whole loop.

References

1. COTO (2016b). TMH9: Manual for Visual Assessment of Road Pavements. Part A: General. Committee Draft Final, May 2016. Original source.Section A.2: degree and extent
2. Department of Transport (1997). TRH12: Flexible Pavement Rehabilitation Investigation and Design. Draft TRH12, Pretoria: Department of Transport for COLTO. Original source.Chapter 1: rehabilitation design process; investigation, evaluation, analysis and economic appraisal
3. CSRA (1996). TRH4: Structural Design of Flexible Pavements for Interurban and Rural Roads. 1996 edition. Original source.Design framework; confirm project applicability
4. CSRA (1994). Draft TRH22: Pavement Management Systems. Pretoria: Department of Transport, 1994. Original source.Technical Addendum A.3, equations A.3.1–A.3.3 and Table A.3.1, printed pp. 125–126; Section 6.2.2, printed pp. 55–56, for alternative-weight normalisation
5. Department of Transport (n.d.). Roads: Engineering Standard Guidelines and Manuals. Official catalogue; accessed 5 September 2026. Original source.TMH22 V8b Draft; TRH12; TRH15; TRH24 catalogue entries
6. COTO (2016k). TMH 9: Manual for Visual Assessment of Road Pavements. Part E: Unpaved Roads. Committee Draft Final, May 2016. Original source.Sections, tables and clauses are cited inline in each guide
7. COTO (2016d). TMH 13: Automated Road Condition Assessments. Part A: General. Committee Draft Final, May 2016. Original source.Sections, tables and clauses are cited inline in each guide
8. COTO (2014). TMH 18: Road Asset Data Electronic Exchange Formats. Draft Version 4, October 2014. Original source.Sections, tables and clauses are cited inline in each guide
9. COTO (2016i). TMH 18: Road Asset Data Electronic Exchange Formats. Committee Draft 5.0, February 2016. Original source.Sections, tables and clauses are cited inline in each guide
10. COTO (2020b). TMH19: Manual for the Visual Assessment of Road Structures. Part A: Road Structure Management Information. Draft Standard, August 2020. Original source.Sections, tables and clauses are cited inline in each guide
11. COTO (2013). Draft TMH 22: Road Asset Management Manual. Draft, March 2013. Original source.Sections, tables and clauses are cited inline in each guide
12. COTO (2017). TMH11: Standard Survey Methods. Version 3.0, April 2017 (the Department of Transport site hosts the Version 2.0 cover page and chapters). Original source.Synopsis: methods written for the practising surveyor
13. RTMC and COTO (2025). TMH24: South African Road Restraint Systems Manual (SARRSM). Draft Standard, version 1.0, July 2025. Original source.Title page and foreword: road restraint systems
14. COTO (2012). TRH 26: South African Road Classification and Access Management Manual (RCAM). Version 1.0, August 2012. Original source.Sections, tables and clauses are cited inline in each guide
15. CSRA (1991). Draft TRH16: Traffic Loading for Pavement and Rehabilitation Design. Draft, December 1991 (printed 1994). Original source.Sections, tables and clauses are cited inline in each guide
16. Department of Transport (2009). Draft TRH 20: Unsealed Roads: Design, Construction and Maintenance. Draft Version 1.5, April 2009. Original source.Sections, tables and clauses are cited inline in each guide
17. COTO (2024). TRH24: Upgrading of Unpaved Roads. Draft Standard, October 2024. Original source.Synopsis: upgrading of unpaved roads
18. SANRAL (2014a). South African Pavement Engineering Manual, Chapter 1: Introduction. Second Edition, October 2014. Original source.Sections, tables and clauses are cited inline in each guide
19. SANRAL (2014k). South African Pavement Engineering Manual, Chapter 6: Road Prism and Pavement Investigations. Second Edition, October 2014. Original source.Sections, tables and clauses are cited inline in each guide
20. SANRAL (2014b). South African Pavement Engineering Manual, Chapter 10: Pavement Design. Second Edition, October 2014. Original source.Sections, tables and clauses are cited inline in each guide
21. SANRAL (2014f). South African Pavement Engineering Manual, Chapter 14: Post-Construction. Second Edition, October 2014. Original source.Sections, tables and clauses are cited inline in each guide
22. COTO (2020a). Standard Specifications for Road and Bridge Works for South African Road Authorities. Draft Standard, October 2020. Original source.Sections, tables and clauses are cited inline in each guide
23. ASB (2010). GRAP 17: Property, Plant and Equipment (Standard of Generally Recognised Accounting Practice). Accounting Standards Board; cover dated February 2010; text version of 1 April 2026. Original source.Sections, tables and clauses are cited inline in each guide

Use the manual edition and project requirements that apply to your work. Worked examples use synthetic values and are not site-specific design advice.