labour-based roads deterioration study: procedure … · 2013-06-20 · labour-based project 1 site...

LABOUR-BASED ROADS DETERIORATION STUDY:PROCEDURE FOR SITE SELECTION, COMMISSIONING AND

MONITORING

CONTENTS

CONTENTS I

1. INTRODUCTION 1

2. SITE SELECTION 1

2.1 DESK STUDY 12.2 FIELD RECONNAISSANCE AND MATERIALS TESTING 22.3 FINAL SELECTION 2

3. SITE COMMISIONING 3

3.1 EQUIPMENT REQUIRED 33.2 INSTALLATION OF PEGS 33.3 PHOTOGRAPHIC SITE RECORD 7

4. MONITORING OF THE TEST SECTIONS 8

4.1 VISUAL CONDITION 84.2 ROUGHNESS MEASUREMENT 8

4.2.1 Merlin Calibration 94.2.2 Measurement Procedure 94.2.3 Number and frequency of measurements 104.2.4 Data Analysis and Presentation 10

4.3 GRAVEL LOSS MEASUREMENT 104.3.1 Peg survey check 114.3.2 Estimating Gravel Loss 11

5. REFERENCES 11

APPENDIX A. PEG SURVEY FORMS – PARTS 1 AND 2. 12

A.1 SURVEYING THE PEGS 13

APPENDIX B. SURFACE CONDITION ASSESSMENT FORM AND GUIDE NOTES 17

APPENDIX C. CROSS SECTION SURVEY FORM. 26

Labour-based project 1 Site set-up and monitoring

LABOUR-BASED GRAVEL ROAD DETERIORATION STUDY:PROCEDURE FOR SITE SELECTION, COMMISSIONING AND

MONITORING

1. INTRODUCTIONOne of the main objectives of the Labour Based Engineering Standards project is todetermine validated relationships for predicting the deterioration of unsealed roadsconstructed by labour-based methods. Sections of roads will be selected, and theirperformance monitored over a period of time. The selected sections will cover a wide rangeof factors including road age, drainage, alignment, terrain, climate, construction material,traffic and construction approach – meaning the level of plant used in construction, e.g. handroller vs. machine roller.

Visual condition, roughness and gravel loss data will be collected and analysed to determinerates of deterioration. If these are found to be significantly different from the relationshipsfound in models such as HDM-4, then the relationships can be modified, - possibly by usingcalibration factors, to produce relationships that are more appropriate for labour-based roads.

This document outlines the recommended procedure for the selection, commissioning andmonitoring of suitable test sections in Uganda.

2. SITE SELECTIONThe project aims to encompass a large number of variables and a wide range of values ofeach variable. The site selection is crucial to this and sites must be selected intelligently toobtain the breadth of data required for the project. The site selection will involve thefollowing activities.

1. Desk study to identify suitable roads

2. Field reconnaissance and materials testing

3. Final selection of test sections

In general, sites should be selected which are representative of Labour-Based roads inUganda. However, sites of special interest for example, sites with a hybrid of labour andplant based construction techniques or sites with unusual materials, should also beconsidered as suitable sites for monitoring.

Once the selection process has been completed the chosen test sections can becommissioned and monitored, as described in sections 3 and 4 respectively.

2.1 Desk Study

A desk study will need to be carried out as a first sift to identify suitable roads. The deskstudy should focus on 3 or four of the variables on which reliable information can be mosteasily obtained without physically going to site. For example the variables looked at may beage, material and climate.

A set of matrixes should then be drawn up and populated with the details of the roads asshown in the example in figure 1.


Wet Climate Dry Clmate

Age Age

MaterialNew 2 – 4

years4+

years

MaterialNew 2 – 4

years4+

years

1Road 1

Road 61

Road 2

2Road 11

2Road 7

Road 12

3Road 5

3Road 3

Road 4

4Road 9

Road 104

Road 8

Figure 1. Example Matrixes from the Desk Study

This will quickly show up areas where there are too many similar roads and other areaswhere there are none or very few identified roads. Not every box in the matrix has to befilled. It is intended to be used as a tool to pick roads that cover the range of variablesrequired and highlight areas where combinations of variables are being replicated and roadscan be struck from the list.

2.2 Field Reconnaissance and Materials Testing

Initial field reconnaissance visits will then be carried out to inspect the roads identified in thedesk study more closely. The field trips should be used to confirm the information in thedesk study and then identify possible 200m test sections based on the variables not alreadylooked at during the desk study, these will most likely be alignment, drainage and terrain etc.Samples of the wearing course material should be taken from these sections for laboratorytesting, the results of these tests will give quantitative data on the materials used inconstruction.

2.3 Final Selection

The final list of test sections should be drawn up based on all of the information collected inthe desk study and field trips including the data from the materials tests. The only limitationon the number of sites selected should be the resources available to carry out themonitoring.

The final list should also include any sites of special interest, for example sections that havebeen constructed using a different approach, or sections which see very high traffic levels, orany other unusual factor which may be of interest.


3. SITE COMMISIONINGOnce suitable test sections have been identified, the sites need to be commissioned. This isa straightforward process involving the establishment of steel pegs at regular intervals onboth sides of the road.

Once the pegs have been installed, a full survey of the pegs will need to be carried out.Details of the survey method can be found in Appendix A. This initial survey information willbe looked at during each subsequent monitoring visit to determine whether the pegs havemoved over time and make the necessary corrections to the cross section profile datacollected to calculate gravel loss.

3.1 Equipment required

For the instrumentation and monitoring of each 200 metre section, the following equipment isrequired:

1. 3 x benchmark pegs. These consist of round, steel rods, each > 1.25m long x 20mmdiameter.

2. 19 x smaller cross-section pegs. These consist of round, steel rods, each 0.75m long x10mm diameter.

3. Auger, 120mm diameter4. Plastic water pipe 100mm external diameter.5. Plastic end caps 100mm internal diameter.6. Cement, aggregate (optional), sand and large water container.7. 3 x plastic bag8. Distance measuring wheel.9. Tools for digging holes and clearing undergrowth; e.g. pickaxe, spades, large bush knife.10. Tools for mixing, moving, compacting and finishing wet concrete; e.g spade(s), large

bowls/buckets, trowel, possibly a wheelbarrow.11. Large hacksaw. 12. Tape (at least 20m in length).13. Large and small hammers.14. Generator, drill and drill bits (see note 1)15. Survey equipment (tripod, level, 2 marked staffs (extendable to 3m), and 3 plain metal

staffs (to use on pegs when holding tape and doing cross sections). 16. Safety equipment; including road signs, high visibility clothing, stop/go boards/flags etc.

Note 1. The generator and drill may be required if the in-situ ground conditions are difficultand the steel cross section pegs cannot be hammered into the ground.

3.2 Installation of pegs

The first task is to mark-out sub-section lengths at 20 metre intervals within the 200 metresection. At the location of each of these cross sections, a metal rod (peg) will be fixed intothe ground on each side of the road. Care should be taken, if possible, to avoid locating thepegs at positions coinciding with side roads, culverts, scour check dams in the side drain orany similar obstacle that might cause problems when measuring the cross section profile atthat location. A typical layout for the test sections is shown in Figure 2.


Figure 2. Plan View of the Peg Layout

20m

= Benchmark Peg

= Cross Section Peg

20m

11L

10L

6L

1L

2L

11R

10R

6R

2R

1R

10m10m

Carriageway


The pegs should be located beyond the side drains in the surrounding terrain. For a typical 6or 7m wide carriageway, the pegs will be located approximately 10 metres transversely fromthe centre line, i.e. 20 metres apart.

If it is not possible to place the pegs at 10m from the centreline (for example if there is asharp drop down an embankment), then the pegs should be located as far as possible fromthe centre line whilst ensuring that they are in a safe location. For ease of future surveyingcalculations, the distance between the pegs should be a whole number of metres. (Forexample, the peg on one side of the road might be placed at a distance of 9m from thecentre line, if this is the furthest point at which it can be safely located).

To place the second peg, fix the first peg and then use the tape to measure where to put thesecond peg (at a fixed number of metres from the first).

If it is not possible to put a peg on one side (e.g. due to a steep embankment or wall), thentwo pegs can be placed in line on one side of the road. When a guide rod is placed on eachof these pegs, a third guide rod can be accurately located on the other side of the road, inline with the other two. This will enable cross section measurements to be accurately madeat the same location each visit.

Two types of steel pegs are to be used; benchmark pegs and cross-section pegs. Thebenchmark pegs are the fixed points against which everything else is measured. It isimportant that they do not move, for this reason they are fixed in a special way. Each siteshould have 3 benchmark pegs to allow for some redundancy. Usually they will be placed atthe beginning and end of the section with the third peg half way along the section.

3.2.1 Installation of Cross-section Pegs

Each marker peg should be hammered into the ground until approximately 50mm is proud ofground level. Soil should then be removed from around the peg to form a hole approximately250mm in diameter and depth. This hole should then be filled with concrete to fix the pegfirmly in position. Before the concrete sets the peg needs to be hammered into the grounduntil about 10mm is proud of the concrete surface. See figure 3.

Figure 3. Finished Cross-section Peg Installation

Labour-based project 6

Some identifying characters can be drawn into the wet concrete surface if desired, to aididentification of the marker peg when the site is revisited.

3.2.2 Installation of Benchmark Pegs

Each of the three benchmark pegs needs to be installed inside a plastic pipe, this will preventsoil movements near the surface from affecting the height of the peg. Figure 4 gives aphotographic record of one such installation.

Initially a hole is dug 200mm wide and nearlybenchmark pegs. Then some concrete is mixdropped into the hole, this ensures that the conthen taken and used to burst the plastic bag ahammered into the ground until the top is appconcrete is then left to cure for a while. The plais put into the hole the bottom of the pipe will sitof the pipe will be about 10mm below the top of tthe steel running through the centre of the pipehold it in position. Finally the end cap is added

Figure 4. Photographic record ofBenchmark peg installation,showing:

• Placement of concrete

• Setting of the steel

• Setting the plastic pipe

• Backfilling around the pipe

• Finished installation with end cap

Site set-up and monitoring

as deep as the steel to be used for theed and put into a plastic bag, this is thencrete rests at the bottom. The steel peg isnd release the concrete. The peg is then

roximately 20mm above ground level. Thestic pipe is then cut to length so that when it just above the concrete surface and the tophe steel. The pipe is placed in the hole with. Soil is then backfilled around the pipe toto prevent objects entering the inside of the


pipe. If desired a thin layer of concrete can be applied around the top of the pipe to createthe illusion of a strong and permanent fixture. Hopefully this will deter people from trying toremove the installation.

3.3 Photographic Site Record

At set-up and at each subsequent survey, a photographic record should be made of the site.

Photographs should consist of:

1. Photographs every 20m. The first should be at the start of the site, then at every set ofpegs.

2. One photograph from the end of the site looking towards the start.

3. Close ups of the gravel surface. Areas should be chosen that are typical of the site.These should show material features such as whether the surface is compacted/loose,cracked/dusty, fine grained/oversize. A scaling object should also be in the pictures sothat the size of material can be estimated. A pen or pencil placed on the road surface isrecommended, better still a measuring tape or ruler. Coins are not recommended sincetheir size will vary between countries.

4. Photographs of any other interesting features.

For photographs of the road, the camera should be set to it’s widest possible field of viewand the amount of sky in the picture should be minimised.


4. MONITORING OF THE TEST SECTIONSThe test sections should be monitored at three to six monthly intervals, depending onresources. If only two surveys a year are possible then the timing of the monitoring shouldbe at the start and end of the wet season. A single monitoring will consist of the followingactivities.

1. Visual condition survey including photographic record

2. Roughness measurement using the Merlin

3. Gravel loss measurement from cross section profiles

4.1 Visual Condition

The visual condition of the unsealed test sections should be recorded for each 20 metrelength over the section, using the pro forma and guide given in Appendix B.

A photographic record of the site should also be made following the guidance in section 3.3.

4.2 Roughness Measurement

The roughness of the sections should be measured with a Merlin roughness measuringinstrument (see Cundill, 1991).

The Merlin can be operated in one of two different modes, the mode of operation depends onthe location of the measuring foot See figure 2. By changing the position of the foot themagnification factor can be set to either 5:1 or 10:1, this dictates how far the chart pointermoves compared to the measurement probe. E.g. when the Merlin is set to 5:1 magnificationthe pointer moves approximately 5mm on the chart for every 1mm the probe moves.

d d

Counterweight

Pivot

5:1 MagnificationProbe Position

10:1 MagnificationProbe Position

Figure 2. Diagram of Merlin Probe Assembly Showing the 2 Probe Positions


Therefor for very rough surfaces the Merlin needs to be set to 5:1 magnification and forsmooth surfaces the Merlin should be set to 10:1 magnification.

4.2.1 Merlin Calibration

Prior to use the Merlin must be calibrated to produce a scaling factor (Sf), this will correct anydiscrepancy in the magnification between the probe and the chart pointer. Determination ofthe Sf is given in detail in TRL Report 229 and is briefly described below.

Calibration is a simple procedure. Place the Merlin on a flat surface, make a mark on theedge of the Merlin chart next to the pointer. A calibration block (usually made from machinedmetal) of known thickness (T), usually about 6 mm, is then placed under the probe and asecond mark is made on the Merlin chart next to the new position of the pointer. Thedistance between these two marks, measured in mm, is the displacement (S).

The Scaling factor, S

TSf

×=

10(equation 1)

e.g. if a block of metal of thickness 6.5 mm, produces a Merlin pointer displacement of 32.5mm, then T=6.5, S=32.5, hence Sf = (10x6.5)/32.5 = 2.

4.2.2 Measurement Procedure

On each site roughness measurements should be taken in accordance with the informationin table 1. Where applicable the number of wheelpaths will usually be two or three, but forvery wide roads four may be visible and should be measured. The number of wheelpathswill vary between sites and may vary on the same site over time. For example, in year 1 asection may have three wheelpaths, but in year 3 there may be only two wheelpaths. Incases where the roughness needs to be measured at fixed offsets, the offsets should bechosen to be where one would expect the wheelpaths to be if they were discernible.

Condition of road Where to measure roughness

Good to moderate All wheelpaths

Poor to moderate condition with distinct wheel tracks All wheelpaths

Poor to moderate condition with no distinct wheel tracks Fixed offsets from the road edge.

Table 1. Where to take roughness measurements.

It is important that the location of each wheelpath or offset measured is clearly identifiable.One way of doing this is to draw a simple diagram of the section on the Merlin data sheet.This should show the name of the nearest large town in each direction, where thewheelpaths are on the carriageway, and also indicate to which wheelpath the data on thesheet relates.

Note that for enhanced safety, advanced warning signs of roadworks should be visible todrivers in both directions to alert drivers. The Merlin operator should wear a high-visibilitysafety vest. It is also often safer to measure the wheelpath against the traffic flow, so thatthe operator is facing oncoming traffic and can see any approaching hazard. This will notaffect the roughness results.


4.2.3 Number and frequency of measurements

The number of Merlin measurements along the section (in each wheelpath) should beapproximately 200 to ensure that the data is representative of the section.

The measurement interval is usually determined by the circumference of the Merlin wheel,i.e. the distance along the ground travelled by one rotation of the wheel, which is usually 2.1metres. Readings are usually made at every full or half revolution of the wheel. Hence for a200m section, if a reading is made every half revolution of the Merlin wheel, thenapproximately 190 readings will be made over the 200m.

calculated from: section length (m) = 200 = approximately 190

measurement spacing 1.05

4.2.4 Data Analysis and Presentation

The procedure of how to calculate IRI from a Merlin chart is given in detail in TRL Report229. This is summarised below for information, but if there is any query the operator mustrefer to this document.

Having completed a Merlin run with approximately 200 readings:

a) Calculate 5% of the total number of Merlin measurements; e.g for 190 readings, 5% =(5/100)x190 = 9.5

b) Count in 5% of readings from each end of the distribution on the Merlin chart and makeone mark at each of these points. Note that fractions should also be included, e.g. if youwanted to measure say 0.5 further in from one end and there were 2 marks in thecolumn, you would measure ¼ of the box (which is usually 5 mm on the Merlin sheet)further in.

c) Measure the distance between these two marks (in mm).

d) Calculate the Merlin D value. This is determined by multiplying the distance measured inc) by the scaling factor (Sf), which should already have been calculated in equation 1.

e) Calculate the IRI for each wheelpath using equation 2:

IRI = 0.593 + (0.0471xD) (equation 2)

f) Calculate the average IRI for the section by taking the mean of the results for eachwheelpath.

The final result should be a single IRI value (in mm/km) for the section.

4.3 Gravel Loss Measurement

Gravel loss is estimated from cross section profiles of the road measured at each pair ofpegs, i.e. every 20 metres along the test section. At each cross section, the spot height ismeasured at 20 cm intervals (called offsets) across the carriageway using a rod and level.The 20 cm intervals are identified using a measuring tape held tightly across the carriagewaybetween a pair of pegs. The spot heights can then be referenced to the benchmarkreadings.


A form for recording the cross section profile measurements at 20 cm intervals is given inAppendix C.

4.3.1 Peg survey check

Before measuring any of the cross section profiles, it is important to check that the pegs havenot moved. The height of each peg should be checked against past records from the originalsurvey to make sure that no pegs have moved from their original position. This is crucial asany movement of the peg will significantly affect the profile and hence estimated gravelthickness and loss.

In the peg survey check, peg heights only need to be measured in one direction i.e from startto end and compared with the site set-up reduced levels. The process of surveying the pegsin one direction should take less than 30 minutes.

If the calculated peg levels differ from the original calibrated levels, then either an error inobservation has been made or a peg has moved. The error needs to be investigated.

4.3.2 Estimating Gravel Loss

The width of the carriageway needs to be determined for each chainage on a test section.Once this width has been defined, the average of the reduced levels across the defined widthwill be used to estimate the height of the gravel wearing-course at each chainage. It isimportant that the same defined width at a chainage is used throughout the monitoringperiod.

The change in the average height of the carriageway between surveys is used as theindicator of the change in gravel loss.

5. REFERENCESCundill, MA. (1991). The Merlin Low-cost Road Roughness Measuring Machine. TRLResearch Report 301. Transport Research Laboratory, Crowthorne, UK.

Cundill, MA. The Merlin Road Roughness Machine: User Guide. TRL Report 229. TransportResearch Laboratory, Crowthorne, UK.


Appendix A. Peg survey forms – Parts 1 and 2.


A.1 Surveying the PegsThe surveying of pegs should be done twice: once from start to end (Peg 1L, 1R, 2L, 2R etc)and then again from end to start (Peg 11R, 11L, 10R, 10L, etc). Forms for recording the pegsurvey measurements (one form for each direction) are given in Appendix 1.

The first benchmark is placed at Peg 1L and the last benchmark is placed at Peg 11R.Normally two benchmarks will be sufficient for a 200-metre section. If more than twobenchmarks are required, then the location of the intermediate benchmarks should be placedat peg locations and their positions noted on the field sheet.

Terminology

Once the level has been set-up (ie by centralising the bubble), a set of readings consists of:

i) backsight – this is the first reading for the set-up

ii) intermediate – these are all subsequent readings, except for the last reading at thecurrent level set-up

iii) foresight – this is the last reading for the set-up

Note 1. Each set-up has only one backsight and one foresight reading. There may be manyor no intermediate readings.

Note 2. If several set-ups of the level are carried out on a test section, (i.e. when the tripodmoves due to insufficient sight distances or height differences, then two readings are takenof the staff on the same peg. One of these readings is from the old tripod position (theforesight) and one from the new tripod position (the backsight). These readings are recordedin the same row because both readings are taken at the same peg location. This procedureenables the two readings to be ‘normalised’.

Procedure and observations

A form for recording the peg levels and calculating the reduced levels is given in Appendix 1.

i) Set the level up within the test section at a point where the staff on the firstbenchmark (Peg 1L) and as many of the other pegs can be observed.

(Note 1 – On a flat section, all the pegs on a 200 metre section should be normallyvisible; on a gradient the level will need to be set up several times. Note 2 – the maximum distance between the level and staff should be 100 metres).

ii) Observe the staff reading on the benchmark (Peg 1L) and record the reading in the‘backsight’ column in line with the first benchmark (Peg 1L) row.

iii) Observe the other staff readings that can be ‘seen’ through the level from its currentposition and record the readings in the ‘intermediate’ column, in line with theappropriate row for the peg. The last point observed from this tripod position shouldbe recorded in the ‘foresight’ column in line with the appropriate peg row.

iv) Move the level to a point where the staff on the last observed peg can still be seen(together with subsequent pegs). Record the staff reading at this peg in the backsightcolumn in the same line as the foresight reading made in the previous set-up.

v) Record the subsequent staff readings which can be observed from this set-up point inthe intermediate column; as before, the last staff reading should be recorded in theforesight column – as described in iii).

vi) This procedure is repeated until the staff reading at the final benchmark (Peg 11R) isrecorded (in the foresight column).


vii) The procedure is then repeated, starting from benchmark 2 ie 11R, and working backin the reverse order. A form for recording the measurements in this direction is alsogiven in Appendix 1.

Calculation of Rise and Falls between pegs

i) For each level set-up (i.e. from a backsight to a foresight reading), calculate thedifference in readings between all consecutive pegs, in the order specified earlier i.e.from Pegs 1L, 1R, 2L, ……11L, 11R), by subtracting a reading from the one above it(e.g. Peg 1L–Peg 1R, Peg 1R–Peg 2L…….). Record the difference in the ‘Rise’column if the difference is +ive and in the ‘Fall’ column if the difference is –ive. NB Ifthe difference is –ive (i.e. in the Fall column), the absolute value can be recorded (i.e.without the –ive sign).

ii) A large error can immediately be seen by calculating the sum of the rises (positivenumbers) and falls (negative numbers) for each direction of the survey andcomparing them. The two totals should be similar, but one will be positive, the othernegative.

iii) The values of the rise/falls between consecutive pegs for each survey directionshould then be compared (e.g. 1L to 1R and 1R to 1L, or 1R to 2L and 2L to 1R). Ifthe difference between the readings is less than 6mm then this is acceptable. If thedifference is greater than 6mm, another survey should be carried out for only thesepegs.

iv) Assuming the difference between each peg and the next is within the limits given in iiiabove, the average of the two values for rise or fall should be taken. This averagechange in height from one peg to the next (in the standard order 1L to 1R to 2L to 2Retc), is then used as the accepted peg height difference and is used to calculate thereduced levels of all the pegs.

Reduced peg levels

Once the average change in height between pegs (rise or fall) has been calculated, all of thepegs are now given their reduced level in relation to the first benchmark. This is done bygiving the benchmark peg 1L a value of 1000.000 and adding the average rise or subtractingthe average fall between it and the next peg. This is continued for all subsequent pegs andwill give one value for each peg that can be used in future surveys to check whether a peghas moved. Eg. 1L = 1000.000, 1R = 998.034, 2L=996.125, etc

Labour-based project Site set-up and monitoring15

Labour-based gravel road survey. Site Set-up: Peg Survey Form Part 1- from start to end

Site DateStart chainageEnd Chainage Surveyor

Chainage Chainage Remark Backsight Intermediate Foresight Rise Fall ReducedNo. (m) Peg No. (B/S) (I/S) (F/S) Level1 Peg 1L (BM1)

Peg 1R2 Peg 2L

Peg 2R3 Peg 3L

Peg 3R4 Peg 4L

Peg 4R5 Peg 5L

Peg 5R6 Peg 6L

Peg 6R7 Peg 7L

Peg 7R8 Peg 8L

Peg 8R9 Peg 9L

Peg 9R10 Peg 10L

Peg 10R11 Peg 11L

Peg 11R (BM2)


Labour-based gravel road survey. Site Set-up: Peg Survey Form Part 2- from end to start

Site DateStart chainageEnd Chainage Surveyor

Chainage Chainage Remark Backsight Intermediate Foresight Rise Fall ReducedNo. (m) Peg No. (B/S) (I/S) (F/S) Level11 Peg 11R (BM2)

Peg 11L10 Peg 10R

Peg 10L9 Peg 9R

Peg 9L8 Peg 8R

Peg 8L7 Peg 7R

Peg 7L6 Peg 6R

Peg 6R5 Peg 5R

Peg 5L4 Peg 4R

Peg 4L3 Peg 3R

Peg 3L2 Peg 2R

Peg 2L1 Peg 1R

Peg 1L (BM1)


Appendix B. Surface Condition Assessment Form and Guide Notes

Condition Survey Form for Unpaved Roads Labour-based road condition survey


ROAD ROAD TYPE DATESECTION ROAD WIDTHKILOMETRE TERRAIN OBSERVER

1 2 3 4 5 6 7 8 9 10

CHAINAGE From 0 20 40 60 80 100 120 140 160 180

SECTION To 20 40 60 80 100 120 140 160 180 200

GRADIENT

CURVATURE

Vegetation

DRAINAGE

Existence

Scouring

LEFT Blockage

SPECIAL DRAINAGE

SLOPES

SHOULDER

Level

SHAPE

SURFACE

CARRIAGEWAY

Vegetation

DRAINAGE

Existence

Scouring

RIGHT Blockage

SPECIAL DRAINAGE

SLOPES

SHOULDER

Level

URGENT

SPOT IMPROVEMENT

GRAVEL THICKNESS

CULVERTS Repair

New

BRIDGES Repair

New

RIVER

Damaged area

Effective width

Damaged area

Crown height

Corrugations

Ruts

Potholes

Loose material

Oversize


Surface condition survey sheet – Guide Notes

The condition survey procedure can be applied in collecting data representing consecutiveunsealed road sections, say up to 1 km long, or sub-sections of a shorter length. The surveycan also be performed at two levels of detail, one of which is more appropriate at a networklevel and the other is more suited for project use.

For the labour-based project, surface condition surveys are conducted at the project level.Generally lengths of 200 metres have been selected as test sections. These sections havebeen split into ten 20-metre sub-sections.

A surface condition form has been adapted for these 200-metre test sections and instructionsfor completing it are given below. The data recording form requires the following informationto be entered:

• General information

• Condition data

The list of items under each category is given in Table 1. The items which must be recordedfor both network and project level surveys are indicated in UPPER CASE. The additionalitems to be recorded for project level surveys are indicated in lower case.

Table 1List of items recorded in the unsealed road condition survey

General Condition data

Road category

Road Number

Road from

Road to

Section Number

Start kilometre (datum)

Description

Date of survey

Road type

Road width

Terrain type

Geometry

VegetationDRAINAGE

ExistenceScouringBlocked

SPECIAL DRAINAGE

SLOPE (CONDITION)Damaged area

SHOULDER (CONDITION)Level

SHAPEEffective width

Crown heightSURFACE (CONDITION)

RutsCorrugations

PotholesLoose material

OversizeURGENT

SPOT IMPROVEMENT

GRAVEL THICKNESS

CULVERTSRequiring repair

New (i.e. required)BRIDGES

Requiring inspectionNew (i.e. required)


1) General Information

Road typeGR - GravelEE - Engineered EarthNE - Natural Earth

TerrainF - FlatR - RollingH - HillyM - Mountainous

Geometry

Horizontal Geometry 0 - Straight1 - Moderate curve2 - Sharp curve

Vertical Geometry 0 - Flat1 - Moderate incline2 - Steep incline

2) Condition Assessment

For items where a code, 0, 1, 2, etc., is employed the most dominant condition should benoted. In all other cases the appropriate quantity or score should be noted.

Vegetation

0 - No loss in sightlines, typically less than 1 m in height.1 - Moderately high, typically between 1 m and 2 m, or significant loss of sightline.2 - High, two metres or more in height, or complete loss of sightline.


DrainageThe overall condition and effectiveness of the drainage system based on the following:

DRAINAGE0 - VERY GOOD Shape and level of drains are in the 'as built' condition.

1 - GOOD Shape and level of drains adequate. Drains functioningeffectively, although minor silting may be evident.

2 - AVERAGE Defects or silting evident but drainage capacity adequate.

3 - POOR Significant defects or silting exist and drainage capacityimpaired.

4 - VERY POOR Serious scouring affecting entire length of section or no drainsprovided.

ExistenceThe presence of a drain and whether it is required was noted as follows:

0 - Exists1 - Not required2 - Required

ScouringThe presence and severity of scouring was noted as follows:

0 - None1 - Slight2 - Severe

BlockageThe presence and severity of any blockage was noted as follows:

0 - None1 - Slight2 - Severe

SPECIAL DRAINAGEThe length of road (in metres) which requires special drainage works was noted. This

item includes the provision or repair of cut off drains, mitre drains, scour checks andprotective bunds.


Side slope

SLOPESThe condition of the side slopes and the area damaged were noted as follows:

Side slope condition0 - No damage1 - Moderate damage2 - Badly damaged

Area damagedThe total surface area in square metres which is damaged.

Shoulder

SHOULDERThe condition of the shoulder was noted as follows:

0 - Good, no damage1 - Moderate damage2 - Severe damage

LevelThe height of the shoulder (including compacted or loose material) relative to the roadsurface was noted as follows:

0 - Level or low1 - High

ShapeThis relates primarily to the cross section shape of the road.

SHAPE0 - VERY GOOD Shape of surface in the 'as built' condition

1 - GOOD Positive camber or crossfall with no ponding of water. Thecamber or crossfall will usually be greater than 4%.

2 - AVERAGE Camber or crossfall at minimum required to shed water.Insignificant ponding of water.

3 - POOR Camber or crossfall insufficient to shed water and waterponding in ruts or areas of concave shape up to 150 mm deep.

4 - VERY POOR Substantial loss of camber or crossfall and water ponding inruts or areas of concave shape up to 300 mm deep.

5 - FAILED Complete loss of shape with water ponding in ruts or areas ofconcave shape greater than 300 mm deep.


Effective widthLength of section or sub-section (in metres) where the road width has been reducedby greater than 1 m.

Crown height0 - As built, or greater than 300 mm above invert of side drain1 - Between 150 mm and 300 mm above invert of side drain2 - Less than 150 mm height difference between invert and crown

Surface conditionThe overall condition of the surface based on the following:

SURFACE0 - VERY GOOD No visible defects, i.e. the running surface is in the 'as built'

condition.

1 - GOOD Low frequency of defects with low severity.

2 - AVERAGE Low frequency of defects with medium severity, or Medium frequency of defects with low severity.(Light grading capable of restoring surface condition unlessextensive potholing and concave shape exists).

3 - POOR Medium frequency of defects with high severity, orHigh frequency of defects with medium severity.(Heavy grading unlikely to restore surface condition if shape is3 or greater).

4 - VERY POOR High frequency of defects with high severity.(Reprocessing capable of restoring condition if shape is 3 orless, otherwise light or heavy reshaping required).

RutsMultiple or single ruts resulting from traffic or water measured under a two metrestraight-edge (or estimated by eye).

0 - None1 - < 15 mm2 - 15 - 50 mm3 - > 50 mm

CorrugationsMeasured under a two metre straight-edge (or estimated by eye).

0 - None1 - < 15 mm2 - 15 - 50 mm3 - > 50 mm

Potholes0 - None1 - 1 - 5 per 50 m2 - 5 - 10 per 50 m3 - > 10 per 50 m


Loose materialThe average depth of loose material on the road surface.

0 - None1 - < 15 mm2 - 15 - 50 mm3 - > 50 mm

OversizeThe presence of oversize particles (typically greater than 5% more than 50 mm)either on or embedded in the road surface.

0 - None1 - Present

Urgent

URGENTWhere urgent action was required to prevent a road becoming impassable, or wherea major safety hazard existed, was noted as follows:

Y - Urgent action requiredN - No urgent action required

NB. Where urgent action is required the Maintenance Superintendent responsiblefor the road section should be notified immediately of the nature of the problem.

Spot Improvement

SPOT IMPROVEMENTThe length (in metres) of section or sub section requiring reconstruction or which isseriously damaged, in which case a spot improvement is required, was noted.

Gravel thickness

GRAVEL THICKNESSThe adequacy of the thickness of the gravel layer was noted as follows:

Y - Existing thickness adequate and no punching through to subgradeobserved

N - Thickness inadequate

Culverts

CULVERTS

Existing culvertsThe number of silted, defective or damaged culverts was noted.

New culvertsThe number of new culverts required was noted.


Bridges

BRIDGES

Existing bridgesThe number of bridges (including drifts) which were damaged and which required adetailed inspection were noted.

New bridgesThe number of new bridges required was noted.

River protection

RIVERThe length of river bank in metres (both sides) which required the repair or provisionof protective measures was noted.


Appendix C. Cross Section Survey Form.

Cross Section Measurement Form Labour-based road condition survey


(for determining gravel loss)

Site Date Site DateChainage No. Centre-line Chainage No. Centre-lineChainage off-set Chainage off-set

Note: The position of the edge of the road surface must be clearly identified below.

Off-set Reading Off-set Reading Off-set Reading Off-set Reading0.000 10.000 0.000 10.0000.200 10.200 0.200 10.2000.400 10.400 0.400 10.4000.600 10.600 0.600 10.6000.800 10.800 0.800 10.8001.000 11.000 1.000 11.0001.200 11.200 1.200 11.2001.400 11.400 1.400 11.4001.600 11.600 1.600 11.6001.800 11.800 1.800 11.8002.000 12.000 2.000 12.0002.200 12.200 2.200 12.2002.400 12.400 2.400 12.4002.600 12.600 2.600 12.6002.800 12.800 2.800 12.8003.000 13.000 3.000 13.0003.200 13.200 3.200 13.2003.400 13.400 3.400 13.4003.600 13.600 3.600 13.6003.800 13.800 3.800 13.8004.000 14.000 4.000 14.0004.200 14.200 4.200 14.2004.400 14.400 4.400 14.4004.600 14.600 4.600 14.6004.800 14.800 4.800 14.8005.000 15.000 5.000 15.0005.200 15.200 5.200 15.2005.400 15.400 5.400 15.4005.600 15.600 5.600 15.6005.800 15.800 5.800 15.8006.000 16.000 6.000 16.0006.200 16.200 6.200 16.2006.400 16.400 6.400 16.4006.600 16.600 6.600 16.6006.800 16.800 6.800 16.8007.000 17.000 7.000 17.0007.200 17.200 7.200 17.2007.400 17.400 7.400 17.4007.600 17.600 7.600 17.6007.800 17.800 7.800 17.8008.000 18.000 8.000 18.0008.200 18.200 8.200 18.2008.400 18.400 8.400 18.4008.600 18.600 8.600 18.6008.800 18.800 8.800 18.8009.000 19.000 9.000 19.0009.200 19.200 9.200 19.2009.400 19.400 9.400 19.4009.600 19.600 9.600 19.6009.800 19.800 9.800 19.800

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Distance peg to peg = Distance peg to peg = Tape height on Left peg = Tape height on Left peg =Tape height on Right peg = Tape height on Right peg =

labour-based roads deterioration study: procedure … · 2013-06-20 · labour-based project 1 site...

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