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PERFORMANCE MONITORING OF RURAL ROADS
IN NORTH WEST LAO
SEACAP 17.02
Dr J R Cook Bounta Meksavanh
BACKGROUNDSEACAP 17 designed and constructed a series of trial sections along rural access roads being upgraded as part of the ADB funded section of the Northern Economic Corridor (NEC) within the Huay Xai district in Bokeo Province. The construction 12 trials sections and associated 7 gravel control sections was completed in August 2007
Standard NEC Gravel.Bamboo Reinf. ConcreteGeocellMortared StoneHand Packed StoneConcrete Blocks.Sand SealOtta SealEng. Natural Surface
ConstructionTrial Options
Why Monitor ?
The development of new pavement requires that their performance be investigated within the road environments within which they are designed to operate. Their deterioration characteristics need to be identified in order to establish their suitability and their Whole Life Costs and define the limits of their appropriate usage
Road Research Delivery
Trial Construction
Practical dissemination
Monitoring & Analysis
Road Standards &Specifications
Gravel Assessment
In addition to the monitoring of the trials roads this project was also undertook a Lao Gravel Assessment Programme (LGAP) with the objective of analysing information on the performance of a number of unsealed roads within the NEC corridor.
New Ref Old Ref From ToPavement Type Start (km) End (km) Length (m)
1011 1-1 B.Phi Mon Sine B.Chom Keo Gravel 0+600 0+700 1001013 1-3 B.Chan Sa Vang B.Si Pho Sai Gravel 1+270 1+370 100
Gravel 0+450 0+550 100Packed Stone 0+700 0+800 100Packed Stone 0+940 1+040 100Single Otta Seal 0+150 0+250 100Double Otta Seal 0+415 0+515 100Engineered Nat. Surface 0+800 0+900 100Mortared Stone 1+200 1+300 100Mortared Stone 1+300 1+400 100Gravel 1+520 1+720 200
1033 3-3 B.Nam Tin B.Phou Vane Kao Gravel 1+650 1+750 100Paving Blocks 0+950 1+050 100Paving Blocks 1+250 1+350 100Bamboo Concrete (125mm) 2+000 2+100 100Bamboo Concrete (150mm) 2+350 2+450 100Geocells (75mm) 2+800 2+900 100Geocells (100mm) 2+950 3+050 100Geocells 3+050 3+125 75Gravel 3+175 3+275 100Gravel 4+550 4+650 100Sand Seal 1+800 1+900 100Sand Seal 2+000 2+100 100Gravel 2+225 2+325 100
Total 2,475
5
8
Monitored Lengths
1032 B.Bolek B.Nam Tong Neua
Roads
2
3-2
108 B.Chom Chouk B.Nam Kham Neua
105 Gam Mining B.Houay Sala
102 B.Nam Phou Kang B.Nam Sa Mok Neua
Data Sets
The following data sets were collected.
Visual survey- using standard sheetsCross sections –levelling techniquesIn Situ pavement layer strength –DCP, IRI Roughness - MERLIN, Mini FWD Rut depth –dipped measurements
The LGAP
This survey of in situ unsealed road conditions was similar in nature to a previous larger SEACAP 4 project carried out in Vietnam as the Rural Road Gravel Assessment Programme (RRGAP). The data collection procedures and forms and associated codes were derived from this project
Ref From To
1011 0+000 2+183 2,183 81013 0+600 3+487 2,887 8102 0+000 5+350 5,350 10
1032 0+000 6+880 6,880 131033 0+000 2+000 2,000 4105 0+000 6+093 6,093 11108 0+000 2+770 2,770 7
Sub-Total 61
1013A 0+000 0+600 600 3102A 0+000 0+800 800 3105A 0+000 3+000 3,000 8108A 0+000 0+500 500 2
Sub-Total 16
201 0+000 12+600 12,600 25202 0+000 4+126 4,126 10
Sub-Total 35Overall Total 112
Package II
Roads Number of GSA Sites Length (km)
Package I SC17 Trial Roads
Bokeo Non-Trial
Trials Data Analysis Key Factors
For each pavement group a number of key factors have been identified that may be reasonably be able to represent road performance,
Trial Group Indicative Factors Trial Group Indicative Factors
Concrete
Joint conditionCrack extentSurface conditionPotholes
Blocks
Block conditionJoint ConditionRutsPotholes
GeocellsStructural crack extentCell conditionJoint condition
Hand Packed Stone
Block conditionJoint ConditionDepressionsPotholes
Sealed Flexible
Crack extentRutsPotholes
Unsealed ErosionRutsPotholes
Left Hand Right HandCarriageway Shoulder Carriageway Shoulder
Cha
in
Block
Sur
face
con
ditio
n
Sto
ne b
lock
s
Mat
rix
Dep
ress
ions
Rut
s
Pot
holes
Sha
pe
Edg
e
Cra
cks
Ero
sion
Run
-off
Dra
in
Sur
face
con
ditio
n
Sto
ne b
lock
s
Mat
rix
Dep
ress
ions
Rut
s
Pot
holes
Sha
pe
edge
Cra
cks
Ero
sion
Run
-off
0 1 1 1 1 0 2 0 1 1 0 1 0 3 1 1 1 0 2 3 1 1 0 1 0
5 2 1 1 1 0 2 0 1 1 0 1 0 3 1 1 1 1 1 0 1 1 0 1 0
10 3 1 1 1 0 2 0 1 1 0 1 0 2 1 1 1 0 2 2 1 1 0 1 0
15 4 1 2 1 0 2 1 1 1 0 1 0 0 1 1 2 0 2 2 1 1 0 2 0
20 5 1 2 1 0 2 0 1 1 0 1 0 0 1 1 1 0 1 0 1 1 0 2 0
25 6 1 1 1 0 2 1 1 1 0 1 0 0 1 1 1 0 1 0 1 1 0 2 0
30 7 2 1 1 0 2 1 1 1 0 1 0 0 2 2 1 1 2 0 1 1 0 1 0
35 8 3 2 2 0 2 1 1 1 0 1 0 0 3 2 2 0 1 0 1 1 0 1 0
40 9 3 2 1 0 2 0 1 1 0 1 0 0 3 2 1 0 2 0 1 1 0 1 0
45 10 2 2 1 1 2 0 1 1 0 1 0 0 1 1 1 0 2 0 1 1 0 2 0
50 11 1 2 1 0 2 0 1 1 0 2 0 0 2 2 1 0 2 0 1 1 0 1 0
55 12 2 1 1 0 2 0 1 1 0 1 2 0 2 1 1 0 2 0 1 1 0 1 0
60 13 2 1 1 0 2 0 1 1 0 1 2 0 2 1 1 0 2 0 1 1 0 1 0
65 14 2 2 1 0 2 1 1 1 0 1 2 0 2 1 1 0 2 0 1 1 0 1 0
70 15 3 3 2 0 2 0 1 1 0 1 0 0 2 2 2 0 2 0 1 1 0 1 0
75 16 3 3 2 0 2 0 1 1 0 1 0 0 3 2 2 0 2 0 1 1 0 1 0
80 17 4 2 3 0 2 0 1 1 0 1 0 0 2 2 1 0 2 0 1 1 0 1 0
85 18 4 2 2 0 2 0 1 1 0 2 0 0 2 2 1 0 2 0 1 1 0 1 0
90 19 3 2 2 0 2 0 1 1 0 3 0 0 2 1 1 0 2 0 1 1 0 1 0
95 20 3 2 2 0 2 0 1 1 0 1 2 0 2 1 1 0 1 0 1 1 0 1 2## 21
The Road Condition Deterioration Index (RCDI)
A total deterioration index: calculated by combining the deterioration of the key factors as percentage of total deterioration (ie all numeric codes at their maximum defect values). Made up of individual factor indices (CDIs)
CDIs3 1 1 1 0
19 3 2 2 0
20 3 2 2 021
43 35 28 143 35 28 1
5 5 5 3100 100 100 60
Bloc
k
Surfa
ce c
ondi
tion
Ston
e bl
ocks
Mat
rix
Dep
ress
ions
1 1 1 1 0
2 1 1 1 0
Deterioration ExtentDefect Extent Index (DEI): simply a
measurement of the % of the road affected by any deterioration. The combination of RCDI and DEI allows a rapid condition assessment.
A high RCDI + high DEI = widespread serious defect
Low RCDI + high DEI = minor widespread defect
Road 24 hr esa Age (Months) esa to date
1011 0.72 20 432
1013 0.24 20 144
102 26.28 20 15768
1032 7.2 20 4320
1033 1.44 20 864
105 7.68 20 4608
108 1.68 20 1008
Traffic
UnsealedRoad Ref. DEI% RCDI IRI
(17.01)IRI
(17.02)Material
1011.01 100 41 8.28 9.07 C
1013.01 100 30 7.46 10.93 F
102.01 100 31 9.51 10.57 C
1032.06 100 15 9.01 7.82 F
1033.01 100 19 7.46 6.08 F
105.08 100 22 7.92 6.08 C
105.09 100 23 7.92 6.97 A
108.03 100 29 7.79 6.08 C
1032.03 100 16 6.02 6.32
Material Suitability
Sealed Flexible Options
Seal DEI% RCDI IRI IRI
Single Otta 63 6 7.19 5.44
Double Otta 83 9 7.31 5.28
Sand 95 23 6.80 5.03Sand 80 30 6.80 5.48
Hand-Packed Stone
Description DEI%
RCDI IRI -1 IRI -2
Non-mortared 100 20 6.59 9.96
Non-mortared 100 30 6.59 10.56
Mortared 100 15 14.2 15.65
Mortared 98 22 11.8 13.36
Geocells
Concrete BlocksRoad Ref. DEI% RCDI IRI
(17.01)IRI
(17.02)105.01 100 15 9.05 6.97105.02 98 13 9.05 5.03
BRCRoad Ref. DEI% RCDI Seals
CDIIRI
(17.01)IRI
(17.02)105.03 10 2 40 11.67 9.07105.04 5 4 41 11.67 7.62
The Lao Gravel Assessment Programme- LGAP
Some Key Issues: Standards
Compared to the SC3 standards the carriageway widths were largely adequate. The overall road widths were however below standard at about 40% of the sites - narrow shoulders
Road Width (Including shoulders)
0
10
20
30
40
50
60
70
80
90
100
3 3.5 4 4.5 5 5.5 6
Width (m)
Cum
ulat
ive
%
Gravel Loss - Gradient
0
10
20
30
40
50
60
70
80
90
100
1 10 100
Loss(mm/yr)
Cum
ulat
ive
%
>6%2-6%0-2%Poly. (>6%)Poly. (2-6%)Poly. (0-2%)
<6%>6%
Gravel Loss mm/yr
Road Shape
Trials Monitoring – General Comment
The SC17.02 survey has emphasised the need for ongoing regular monitoring of the Bokeo trial sites if any meaningful outcomes are to be achieved from the initial outlay on this programme.
LGAP- OutcomesUnsealed gravel roads can be a sustainable option in Lao - but only with maintenancethat must include a shaping capacity.
The combination of unsealed roads at gradients less than 6% and Spot Improvements on sections >6% can provide a Lao with major tool to address their poverty alleviation aims through improved access.