Download Roughness Manual - Roads and Highways Department

Government of the People’s Republic of Bangladesh
Ministry of Communications
Roads and Highways Department
ROAD ROUGHNESS SURVEY MANUAL
OCTOBER 2001
Ministry of Communication
Roads and Highways Department
Road Roughness
Survey Manual
TABLE OF CONTENTS
1. INTRODUCTION ................................................................................................... 3
2. TIMING OF ROUGHNESS MEASUREMENT....................................................... 3
3. EQUIPMENT NEEDED ......................................................................................... 3
3.1 DESCRIPTION OF EQUIPMENT ................................................................... 3
3.1.1 Vehicles .................................................................................................... 3
3.1.2 Bump Integrator ........................................................................................ 4
3.1.3 Distance Measurement Equipment .......................................................... 5
3.1.4 Merlin ........................................................................................................ 5
4. ACTIVITIES INVOLVED........................................................................................ 6
4.1 CALIBRATION OF CNS FARNELL DISTANCE ODOMETER ..................................... 6
4.2 DOING THE MERLIN EXERCISE ........................................................................... 6
4.2.1 Selection of site ........................................................................................ 7
4.2.2 Doing the MERLIN Survey ....................................................................... 7
4.2.3 Running Vehicles on Merlin Sites............................................................. 7
4.2.4 Doing the Regression Analysis................................................................. 8
5. DOING THE ACTUAL ROUGHNESS SURVEY................................................... 9
5.1.1
5.1.2
Survey team.............................................................................................. 9
Survey Methodology ............................................................................... 10
6. DATA ENTRY...................................................................................................... 11
Picture 1
Picture 2
Picture 3
Picture 4
Picture 5
Picture 6
Bump Integrator ........................................................................................... 4
Counter Unit Bump Integrator...................................................................... 4
Distance Meter............................................................................................. 5
Merlin in use................................................................................................. 5
Merlin Worksheet ......................................................................................... 8
Regression analysis chart............................................................................ 9
Appendix 1
CNS Farnell Distance Odometer
Appendix 2
Merlin Manual
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Ministry of Communication
Roads and Highways Department
Road Roughness
Survey Manual
1. INTRODUCTION
Maintenance of road is dependent on several factors, one of which is the condition of
the pavement surface. To determine what treatment is necessary the condition of the
surface is to be known. Roughness is the measurement of riding quality, which in
turn is the effect of total surface deterioration.
In Roads and Highways Department (RHD) the HDM Circle has the responsibility to
produce the priority list of the Annual Road Maintenance Programme using HDM-4
software. Roughness of roads in terms of IRI has the greatest influence in the HDM
analysis. So correct measurement of Roughness is a prerequisite for doing the
correct HDM analysis.
In addition the HDM Circle of RHD is responsible to do the roughness measurement
of all paved roads within the RHD Road Network. This instruction manual has been
prepared solely for use within RHD and describes the measurement methods that
are being adopted for the road roughness measurement.
This guide is accessible on the RHD Intranet:
2. TIMING OF ROUGHNESS MEASUREMENT
Roughness measurement is done annually preferably from October to December. To
measure the roughness of all paved roads takes about three months if 3 nos. of
vehicles are used for the survey.
3. EQUIPMENT NEEDED
Following equipment are needed for the roughness measurement:
•
•
•
•
Vehicles (Pickup or Jeep)
Bump Integrator
Distance Measurement Equipment (CSN Farnell)
TRL MERLIN
Other materials and stationers required are:
•
•
•
•
3.1
Paint and brush
Graph papers (cm scale)
Wooden pencils
Jute ropes
DESCRIPTION OF EQUIPMENT
3.1.1 Vehicles
Generally pickup and Jeep are well suited for the survey. Bump integrator is fitted on
the vehicle just above the rear axle. A steel hook is welded to the differential so that a
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E:\Documents\Roughness Manual\Road Roughness Survey Manual.doc
Ministry of Communication
Roads and Highways Department
Road Roughness
Survey Manual
1. INTRODUCTION
Maintenance of road is dependent on several factors, one of which is the condition of
the pavement surface. To determine what treatment is necessary the condition of the
surface is to be known. Roughness is the measurement of riding quality, which in
turn is the effect of total surface deterioration.
In Roads and Highways Department (RHD) the HDM Circle has the responsibility to
produce the priority list of the Annual Road Maintenance Programme using HDM-4
software. Roughness of roads in terms of IRI has the greatest influence in the HDM
analysis. So correct measurement of Roughness is a prerequisite for doing the
correct HDM analysis.
In addition the HDM Circle of RHD is responsible to do the roughness measurement
of all paved roads within the RHD Road Network. This instruction manual has been
prepared solely for use within RHD and describes the measurement methods that
are being adopted for the road roughness measurement.
This guide is accessible on the RHD Intranet:
2. TIMING OF ROUGHNESS MEASUREMENT
Roughness measurement is done annually preferably from October to December. To
measure the roughness of all paved roads takes about three months if 3 nos. of
vehicles are used for the survey.
3. EQUIPMENT NEEDED
Following equipment are needed for the roughness measurement:
•
•
•
•
Vehicles (Pickup or Jeep)
Bump Integrator
Distance Measurement Equipment (CSN Farnell)
TRL MERLIN
Other materials and stationers required are:
•
•
•
•
3.1
Paint and brush
Graph papers (cm scale)
Wooden pencils
Jute ropes
DESCRIPTION OF EQUIPMENT
3.1.1 Vehicles
Generally pickup and Jeep are well suited for the survey. Bump integrator is fitted on
the vehicle just above the rear axle. A steel hook is welded to the differential so that a
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Ministry of Communication
Roads and Highways Department
Road Roughness
Survey Manual
steel wire can be connected tightly between the hook and the spring-loaded pulley of
the bump integrator by passing the wire through a hole made in the body of the
vehicle. There are many factors concerning the vehicle that will affect the readings
from the bump integrator:
•
•
•
•
•
•
•
Stiffness of the vehicle suspension
Condition of the shock absorbers
Vehicle tyre pressure
Gross vehicle weight
General condition of the vehicle and engine
Speed of the vehicle
Driver behavior
RHD 3 nos. of pickups are being used since last few years for the roughness
measurement.
3.1.2 Bump Integrator
The unit works by sensing the movement between the body of the vehicle, to which
the bump integrator (BI) is mounted, and the rear axle. A cable to a counter unit
connects the BI unit. This has two digital displays which can be switched on and off
alternatively by a two-way switch. Each display has a clear button.
Picture 1
Bump Integrator
Picture 2
Counter Unit Bump Integrator
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Ministry of Communication
Roads and Highways Department
Road Roughness
Survey Manual
3.1.3 Distance Measurement Equipment
For measuring the distance in kilometer, a CNS Farnell Distance Odometer is being
used. The manual is enclosed with this instruction guide for reference (Appendix -1).
Picture 3
Distance Odometer
3.1.4 Merlin
The MERLIN is a Machine for Evaluating Roughness using Low-cost
INstrumentation. The Transport Research Laboratory (TRL) of United Kingdom
devised this equipment. The Merlin manual of TRL is enclosed herewith for reference
(Appendix -2).
Merlin is simple low-cost roughness measurement instrument that can be
manufactured locally. The instrument can be used for direct roughness measurement
or for calibrating other equipment like Bump Integrator. In RHD Merlin is used for
calibrating purpose. It consists of a metal frame 1.8 meters long with a wheel at the
front, a foot at the rear and a probe midway between them which rests on the road
surface. The probe is attached to a moving arm, at the other end of, which is a
pointer that moves over a chart. The Merlin is wheeled on the road and at every turn
of the wheel the position of the pointer is recorded on the chart to build up a
histogram. The width of the histogram can be used to give a good estimate of
roughness in terms of International Roughness Index (IRI).
The critical measurements are the ratio of the long and short sections of the moving
arm that must be 10. If there is any deviation from this ratio, a correction factor must
be used to obtain the correct roughness from the Merlin measurement. As an
example, if the ratio of the sections of the moving arm is 9.75 then the movement of
the pointer will be less by a factor of 0.975 (9.75/10). Therefore, the width of the
histogram (D) will have to be increased by a multiplying factor of 1.03 (10/9.75) to
get the correct roughness
Picture 4
Merlin in use
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Ministry of Communication
Roads and Highways Department
Road Roughness
Survey Manual
4. ACTIVITIES INVOLVED
The roughness survey requires several activities of which each one has the effect on
the other. The activities are as follows.
4.1
Calibration of CNS Farnell Distance Odometer
During the actual survey bump readings are noted after travelling every 0.5-km of
road. Therefore a correct calibration of the distance odometer is required.
See the enclosed CNS Farnell Distance Odometer Manual for instructions.
4.2
Doing the Merlin Exercise
This is done to get the correct roughness of a particular portion of a road so that if a
vehicle fitted with a Bump Integrator is run over that portion, the relative bump counts
for the known roughness could be known. In this way if the relative roughness and
bump counts of say 10 sites of different roughness are known, then a relationship
between the roughness and bumps can be established by doing a regression
analysis.
In RHD generally 10 to 11 sites are surveyed with Merlin to obtain the actual
roughness of individual site. The sites are initially selected in such a way to give
varying roughness low and high. Each survey vehicle is then run on those sites to
obtain the bump counts against the corresponding roughness of sites and lastly the
regression analysis is done to get the relationship of roughness and bump counts of
individual vehicle.
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Ministry of Communication
Roads and Highways Department
Road Roughness
Survey Manual
4.2.1 Selection of site
Selection of site is very important because sites should be of varying roughness low
and high. It may be difficult to get the road with low roughness and similar the case
with high roughness. However, from the experience it was seen that roads of low
roughness like 2.00 IRI were available and on the high range 8.00 to 8.50 or 9.00
were also available. Use the bump integrator and the distance odometer during site
selection. When driving upon a test site have the bump integrator on and keep the
distance odometer open. Note down the bump counts for every 0.5-km. The more the
bump counts the more will be the possible roughness.
4.2.2 Doing the MERLIN Survey
Generally two Merlins are used for the survey. Put a mark on the rod with paint at the
starting. Place the Merlins side by side so that each Merlin is on the wheel track, the
outer and the inner. Always follow the left side of the road. One vehicle should be at
the back of the survey team and the other at the front with flags for the safety reason.
Fix graph sheets on the steel plates of the Merlins over which the pointer moves.
Now move the Merlin forward one complete rotation of the wheel, see the position of
the pointer and put a cross mark on the graph sheet. In this way after every rotation
of the Merlin put a mark on the graph sheet at the position of the pointer. Continue
doing this for 200 rotations of the Merlin wheel and again put a mark on the road by
drawing a line by paint. To keep a correct counting of the no of rotations, a tally box
of 200 small squares of the graph sheet can be utilized. After every rotation one
square can be marked so that after 200 rotations the 200 squares of the tally box will
be completely marked. When 200 rotations will be completed, a histogram like the
one shown below will be built in the graph paper. The positions mid-way between the
tenth and the eleventh crosses, counting in from each end of the distribution, are
marked on the chart below the columns. It may be necessary to interpolate between
column boundaries as shown in the figure below. The spacing between the two
marks, D, is then measured in millimeters and this is the roughness on the Merlin
scale. It is to be noted that the final D-value will be the average of D-values obtained
from two Merlins. Once the final D-value is obtained substitute it the standard formula
given the Merlin guide to get the roughness in IRI. The formula is as follows.
IRI=0.593+0.0471D
Where,
IRI is the roughness in terms of International Roughness Index in meters per
kilometer.
D is the roughness in terms of Merlin scale in millimeters (the base of the histogram)
Do the Merlin survey in 10 or 11 sites of varying roughness.
4.2.3 Running Vehicles on Merlin Sites
When the Merlin survey is completed, the vehicles fitted with Bump Integrators are to
be run on the sites to get the bump readings corresponding to the roughness of every
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Ministry of Communication
Roads and Highways Department
Road Roughness
Survey Manual
site. Bump readings are to be taken for the distance between the paint marks put
during the survey. Be sure that the vehicle is run at a speed of 20-mph (32 km/h). To
attain the speed, start running the vehicle from at least 100m back of the starting
mark. When the vehicle reaches the start mark, make the Bump Integrator on and
stop the Bump Integrator at the end mark. Note down the bump count thus obtained.
Do this exercise several times to get at least four consistent readings and average
them. This average bump reading represents the bump count against the roughness
obtained by Merlin. In this way run other survey vehicles in each site and get the
corresponding bump counts against the roughness.
4.2.4 Doing the Regression Analysis
On next page is a worksheet showing the data of nine Merlin sites. The D-value of
each Merlin has been corrected using the correction factors of Merlins.
Picture 5
Merlin Worksheet
Left Merlin
Right Merlin
Merlin
D
Corrected Merlin
D
Corrected Average IRI
Bump
Bump
No
value D-value
No value D-value D-value m/km Reading reading /
Car-1
Km
Site
No
Date of
survey
4
15/11/2000
2
25
29
1
25
28
29
1.9
44
98
5
15/11/2000
2
28
33
1
27
30
31
2.1
44
98
1
15/11/2000
2
69
80
1
68
76
78
4.3
119
267
9
16/11/2000
2
84
98
1
74
83
90
4.9
133
296
2
15/11/2000
2
86
100
1
73
82
91
4.9
128
287
3
15/11/2000
2
88
103
1
75
84
93
5.0
126
282
8
16/11/2000
2
88
103
1
89
100
101
5.4
155
347
6
16/11/2000
2
99
115
1
90
101
108
5.7
152
339
7
16/11/2000
2
113
132
1
110
123
128
6.6
187
418
Length of every Merlin site = 446.97-m
The regression analysis chart with the line fit plot and the formula obtained for the
Roughness and Bump-count relationship is shown below.
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Picture 6
Road Roughness
Survey Manual
Regression analysis chart
C a lib r a t i o n o f B u m p I n t e g r a t o r - 2 0 0 0
Vehicle Code=4, Reg no 02-0010
7.00
y = 0.0144x + 0.6242
6.00
2
R = 0.987
5.00
4.00
3.00
Y
Linear (Y)
2.00
1.00
0.00
0
50
100
150
200
250
300
350
400
450
Bump Reading
5. DOING THE ACTUAL ROUGHNESS SURVEY
The vehicles calibrated by the above method are then used for actual survey. The
intention is to collect the bump counts at every 0.5-km of roads. These bump counts
are utilized to get the roughness of road by using the formula obtained from the
above regression analysis.
5.1.1 Survey team
The survey team for vehicle consists of:
•
•
•
Driver
Assistant Engineer
Assistant
The driver plays the important role during the survey. He keeps the vehicle well
maintained. During survey he drives carefully to maintain the speed, avoids abrupt
jumping of vehicle. He should be able to connect the equipment correctly and should
be well aware about the activities involved during the survey. Each driver should be
given training before going out for actual survey.
The other two members of the team will collect the data. One of them will call out the
reading at every 0.5-km and the other person will note down those in the standard
form prepared for the survey. Survey is done for the individual links of the RHD Road
Network. Survey must start from the starting point of the link. In case if the survey is
started from other than start point of the link then the actual chainage of the start
point must be entered in the distance odometer during the start of the survey. If in
any journey more than one links are surveyed then the bump counter must be zeroed
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Survey Manual
at the start of each link and similarly the distance odometer should also be zeroed to
avoid mistakes in writing the chainage.
5.1.2 Survey Methodology
Prepare the equipment:
•
•
•
•
•
Ensure that the wire of bump integrator is properly suspended with the hook
below.
Connect the cables of the bump counters and the distance odometer properly.
Check that Bump counter and distance odometer displays are OK.
Switch on the distance odometer.
Turn the two-way switch of bump counter to counter1. Do not switch on.
The team is now ready to start the survey. Proceed as follows:
1. Position the vehicle about 50 to 100 meters back of the starting point of the
survey.
2. Start driving the vehicle so that it gains the proper speed (32 km/h) at the start
point.
3. As soon as the vehicle reaches the start point operate the distance odometer and
the bump integrator simultaneously. Make sure that the distance odometer as
well as the bump integrator is switch on.
4. As the vehicle moves along the road, the bump counter will display the bump
readings and will continue to increase as the vehicle gets bump during running.
The distance odometer will continue to display the actual distance being
travelling.
5. When the vehicle reaches 0.5 km (as will be seen in the distance odometer) turn
the two-way switch of bump integrator to counter-2. This will cause the counter-2
to continue displaying the bump reading and counter-1 will stop recording. Read
the reading of counter-1 and call out so that the assistant can note down the
reading in the form.
6. When the vehicle reaches 1.0 km turn the two-way switch towards counter-1.
Now counter-1 will again continue to display cumulative readings and counter-2
will stop recording bumps. Read the reading on counter-2 and call out. Also
record the time.
7. In this way continue driving vehicle and at each 0.5-km read the corresponding
bump counts and time and record those on the sheet.
8. Stop the vehicle when the survey for a link is completed.
9. Please record the closing distance exactly from the distance odometer. The final
section, which is less than 0.5 km is, called the closing fraction.
At this point please note that if the link you surveyed is a narrow road (single lane say
4m) then you do not need to survey back to the start of the link. Otherwise you will
have to collect bump readings of the other side of the road by doing a back survey
from the end of the link to the start point. During the back journey, record the bump
counts against the corresponding chainage already recorded in the sheet which
means that you have to start writing bump counts on the sheet from bottom to top.
During back journey repeat step 1 and 2 above. Drive to the distance amounting to
the closing fraction and clear the distance odometer. Read the bump reading and
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Survey Manual
record it on the form. After that read the bump counts at every 0.5-km and record
accordingly.
6. DATA ENTRY
The RMMS software of RHD includes standard data entry screen in which the
surveyed bump counts are entered so that data is automatically stored in the RHD
server. Please see the RMMS user manual for detail information about roughness
data entry, data editing and reports.
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Ministry of Communication
Roads and Highways Department
Road Roughness
Survey Manual
record it on the form. After that read the bump counts at every 0.5-km and record
accordingly.
6. DATA ENTRY
The RMMS software of RHD includes standard data entry screen in which the
surveyed bump counts are entered so that data is automatically stored in the RHD
server. Please see the RMMS user manual for detail information about roughness
data entry, data editing and reports.
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Appendix 1
CNS Farnell Distance Odometer
APPENDIX 2
MERLIN MANUAL