22TCN 210-92 PDF

defined under “22TCN Standard” released in by MOT (Ministry of. Transport) or the transportation works grade higher as defined. requirements” 22TCN issued by MoT (Ministry of Transport) in or road of higher quality as defined under “High-way design. Basic norms of road according to standard 22 TCN and decision. / /QD-BGTVT. Basic norms. Road from District to. Commune.

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Documents Flashcards Grammar checker. These trial sections of the Buon Ho road were designed with four different pavement options based on existing Commune Class 210-2 standards and the research guidelines developed for the RRSR programme.

It was reported by local sources that uncontrolled heavy vehicle traffic had started to use the Buon Ho trial road almost immediately after completion and that rapid deterioration of the pavement had then taken place and continued until, by latethe condition had deteriorated to such an extent in some places that most of this traffic opted not to use the 210-992.

The investigation showed that Buon Ho road has suffered significant and rapid deterioration leading in places to complete pavement failure, but that the pavement condition is not uniform and there are significant lengths with only slight or moderate deterioration and other areas where no deterioration is evident. There is significant evidence to indicate that the trial road was, at least in part, constructed with materials that did not meet the specifications and, possibly, to variable compaction standards.

The markedly different performance of sections of the same design but built by different contractors, further indicates that the 210-29 of materials and the quality of construction probably significant factors.

Analysis of traffic patterns and the results from a specially commissioned axle load survey showed that in the first six to seven months since construction the Buon Ho road had most likely carried a traffic load ofesa. This is in contrast to the design value ofesa over a ten year design life.

In addition, a significant numbers of vehicles were above the Commune A axle load limit of 6T. The principal conclusions of this 22hcn are: The pavement design was suitable for Commune road A traffic. Some sections of the road were constructed with materials that were out-of-specification but even so the as-built condition was generally suitable for Commune road A traffic although some sections would have required periodic maintenance during a year design life.

The original design and hence the as-built road were totally inadequate for the traffic it actually carried.


The primary cause of road failure was the excessive amount of traffic load that the road had carried within months of its completion, but that the rate of this deterioration was aided 22tfn some extent by marginal or poor construction in some sections. It is recommended to reconstruct the road to meet Province Road standards of pavement strength and geometry, taking full account of the likely heavy traffic.

However if the intention is to retain the Buon Ho as a Commune Road then any rehabilitation must be accompanied by stringent measures to restrict large and overloaded trucks. Additional recommendations are made as to: The importance of appropriate asset management of rural infrastructure. The need to re-assess of rural road design standards based on the actual and anticipated tasks they will be asked to perform. The need to improve levels of effective site control on construction procedures and material usage.

The RRST-II programme was undertaken in a wider set of physical 22tcnn than RRST-I and was seen as an important step in the roll out and mainstreaming of sustainable and appropriate rural surfacing solutions. Supervision was undertaken by local consultants with Intech-TRL taking an overall Quality Assurance and strategic guidance role. The 22tc roads in Dak Lak were completed by July and shortly after that in December two roads Buon Ho and Ea Soup were reported to have suffered rapid deterioration on some of their trial sections.

The Dak Lak trial roads are located within the Central Highlands region of Vietnam, Figure 1 Figure 1 Trials Location The Buon Ho deterioration was confirmed during a condition monitoring survey in March and recommendations were made as a research programme to investigate the causes1.

This has been interpreted to mean, in practical terms, that the project will research the background and current pavement conditions to determine the contributing cause, or causes, of early failure and to make recommendations on the prevention of similar situations occurring elsewhere.


Proposals were submitted in September and, following a period of negotiation, a contract was signed between TRL Ltd and Crown Agents in November Recommendations as to the prevention of similar failures occurring in the future programmes are also presented. A 22tnc report deals with the partial deterioration of the Ea Soup Road. Intech-TRL, under a separate contract, was responsible only for advising ITST on supervision 20-92 and for the final quality assurance assessment of the completed roads.

Visits were made by Intech-TRL to Buon Ho as part of the consultation process and relevant information gathered by a walk-over survey in June This included in situ DCP testing evaluation of the existing road surface, see Figure 2 and Figure 3. The existing surface was seen to be in 22fcn condition and composed of sub-standard quality gravely silty clay.

Buon Ho Layer Thickness mm 50 0 8. Key aspects of these specifications are summarised in Appendix A. However, under special arrangements agreed by the MoT for the RRST trials, the following additional supervision procedures were also in place: This included undertaking quality control tests during construction and agreeing the satisfactory completion of the pavement layers.

During the construction period, Intech-TRL staff made periodic visits to Dak Lak to comment on progress and quality control.

During one of 22ctn visits the poor quality of the gravel sub-base for Sections BH5 and BH 6 was noted and a change of materials was recommended. It should be noted that test results for as-delivered construction 22tccn were not submitted to Intech-TRL until after completion of construction.

An Intech-TRL Quality Assurance team visited the completed roads in June to conduct an assessment of as-built quality based on available evidence. This survey was then combined with an assessment of available test data to give an overall Quality Assessment as summarised in Table 2. Some unsatisfactory issues or missing data C: Unsatisfactory In addition, the following specific points were made; 1. Crossfalls were not as specified in all sections except section 6 2.

There was a lack of some quality control DCP test results Some CBR laboratory test results from as-delivered material were low Some particle size distributions for DBM and WBM aggregate were poor There was insufficient site and laboratory data from section 4 During the construction period, the PDoT indicated that they proposed to upgrade this road to provincial level and observations by Intech-TRL of traffic using completed sections indicated that there was already a significant risk of heavy traffic using the road.

Recommendations on this were made to the PDoT in regard to the unsuitability of using a Commune A pavement design for provincial level traffic and the consequent desirability of restricting heavy vehicles using the Buon Ho road. Heavy traffic and overloading is a problem on rural roads in the area and the roads should be wider 5m and road designed for 10t.

Upgrading standards were not an issue for RRST. The following sections were reported as suffering from severe rutting of the pavement, cracking of the surface seals and erosion of some base aggregate: The following were the principal points raised in the subsequent report. Thus not only do they avoid going 222tcn Buon Ma Thuot city, thereby saving 70km, they also avoid the toll station near Buon Ho town.

Some short sections of trial road are damaged because of the overloaded vehicles. Provinces in the Central Highland are unwilling or unable to use barriers to control the heavy vehicles. There are load limit signs along the road but drivers do not comply with these restrictions.

Numerous heavy vehicles were noted and photographed using the road. According to local residents, the heavy vehicle traffic continues during the night up to around hrs. It is understood that uncontrolled heavy vehicle traffic continued to use the Buon Ho trial road and that rapid deterioration of the pavement continued until, by latethe condition had deteriorated to such an extent in some places that most of this traffic opted not to use the road.

The 22ttcn locations for inspection pits were identified on site. In order to gain maximum research information it was agreed that these pits would be on a variety of pavement conditions.

The main data collection phase comprised the following: A separate report on this survey is incorporated as Appendix B to this document and discussion of its results included in Chapter 4 below. Locations of these pits are listed in Table 4.

Inspection pit records are included as Appendix C. In situ DCP testing was undertaken on pavement layers within the inspection pits where appropriate. Key test results are summarised in Tables 5 and 6. The coded visual survey sheets are included in Appendix F along with tabulated summary descriptions.


Figures 4 to 8 present the wheel-track rut depths measured as part of the visual survey procedure. Descriptions are grouped into 5 general levels of condition as defined below and presented in Figure 9, which also includes test pit locations, pavement design references and contractor boundaries. Pavement in fair condition, with some slight stripping of seals leading to occasional shallow potholes; occasional rutting up to 20mm, occasional interconnected or crocodile cracking 3.

Pavement in moderately poor condition, with significant crocodile cracking and scattered potholes, rutting may be up to mm 4. Pavement in bad condition, extensive crocodile cracking and potholes with rutting up to mm 5.

Pavement in very bad condition — essentially pavement has lost seal and lost integrity with severe ruts and loosening of base material. Rut depths for Section BH3 Rutting: Buon Ho road has suffered significant and rapid deterioration leading in places to complete pavement failure. The poor pavement condition is not uniform and there are significant lengths with only slight or moderate deterioration and other areas where no deterioration is evident.

Two sections BH5 and BH6 with the same design, but built by different contractors, are exhibiting markedly different performance characteristics, Figure Sections with the same contractor but different designs are exhibiting significantly different performance characteristics, for example compare Figure 5 and Figure 6.

The test results for construction materials submitted prior to construction indicated a general compliance with specification. No adverse comments were received from the local supervision team on the subsequently as-delivered materials.

Following a site visit during construction, Intech-TRL requested replacement of existing gravel sources with an improved material. Assessment of materials recovered from the inspection pits indicates that this request was not acted upon. In situ and laboratory testing indicates low strength and out-of specification gravel sub-base within sections BH5 and BH6.

During the current investigations, visual and laboratory evidence indicates that the as-built Penetration Macadam, WBM and DBM pavement layers contain significant oversize material. There is also evidence in some places of segregation of the fines. Visual evidence indicates some variability in the quality of the bitumen surfacing.

Laboratory testing indicate a low bitumen content for the Penetration Macadam sections, although this may well be at least partially a result of sampling problems with this form of pavement. Assessment of the layer thickness indicated no significant thinning of the base or sub-base layers beneath carriageway ruts. In summary, there is significant evidence to indicate that the trial road was, at least in part, constructed with materials that did not meet the specifications and, possibly, to variable compaction standards.

The markedly different performance of sections BH5 and BH6, which are nominally the same design but built by different contractors, indicates that the quality of materials and the quality of construction are significant factors.

However, these figures indicate an ESA total of between 75, andfor a 10 year design life.

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2210-92 noted previously, after the trial road was constructed, traffic increased rapidly but decreased again when the road began to deteriorate. For this investigation it is important to obtain an estimate of the traffic loading that the trial road carried during this period of heavy trafficking.

Vehicles travelling from the East on RN 26 to the North on RN 14 and vice versa were able to reduce their journey distance by about 70 km by using the trial road as a short cut and this also enabled them to avoid the toll station on NR Five traffic count stations are shown from which traffic count data are available for the yearsand The traffic counting period was between 6.

According to local information, a considerable volume of truck traffic travelled at night on the trial road. Analysis of the data from these counting stations can be used to estimate the traffic that used the trial road when it was opened to traffic. The other traffic counts are useful because they provide 22tcm concerning the general growth rate of traffic in the area. The traffic counts are tabulated in Appendix F.