BRC Road Condition Assessment Manual

1. Overview

The purpose of this manual is give assistance to staff and contractors assessing the condition of roads & related assets throughout the Bundaberg Regional Council, and to document how the road condition scores currently in Council's Asset Management System have been ascertained.

2. Sealed Roads

The overall condition of sealed roads is to be described by two parameters; Pavement Condition Index (PCI) and Surface Condition Index (SCI).
The PCI of a road section is a function of its roughness, and the extent and severity of crocodile cracking, rutting & patching.
The SCI of a section is determined by its roughness, and the extent and severity of environmental cracking, stripping & potholes.

2.1 Roughness

Roughness is a condition parameter used to characterise deviations from the intended longitudinal profile of a road surface. Roughness data is typically measured with a laser profiler installed into a purpose built survey vehicle. An IRI score is recorded for each 10m section of road, and this data is averaged out over the length of each road segment.

The roughness score is used in calculating both the PCI and SCI for sealed roads.

2.2. Crocodile Cracking

Crocodile Cracking is interconnecting or interlaced cracking in a road seal resembling the hide of a crocodile. Cell sizes can vary in size up to 300mm across, but are typically less than 150mm across.

Crocodile-Cracking-Baragra-Qld-Jun-18-2009a.jpg

Both the extent & severity of crocodile cracking needs to be ascertained.

2.2.1 Crocodile Cracking Severity

The severity of crocodile cracking is determined by the width of cracks. Each 10m section of road is given a crack severity score in the range 0-3.

SEVERITY
Score Crack Width
0 no cracking
1 less than 2mm
2 2mm to 5mm
3 >5mm

The overall score for the road segment is the average of the individual scores.

2.2.2 Crocodile Cracking Extent

The extent of crocodile cracking is determined by the pecentage of road surface that is subject to cracking. Each 10m section of road is given a crack extent score in the range 0-3.

EXTENT
Score Area subject to cracking
0 no cracking
1 less than 5%
2 5% to 15%
3 more than 15%

The overall score for the road segment is the average of the individual scores.

2.3 Environmental Cracking (Block / Diagonal / Longitudinal / Transverse)

longitudinal-cracking.JPG parallel-longitudinal-cracks.JPG Montrose-Reflective-Block.JPG High-Rd-Shrinkage-FB1.JPG

Both the extent & severity of environmental cracking needs to be ascertained.

2.3.1 Environmental Cracking Severity

The severity of environmental cracking is determined by the width of cracks. Each 10m section of road is given a crack severity score in the range 0-3.

SEVERITY
Score Crack Width
0 no cracking
1 less than 2mm
2 2mm to 5mm
3 >5mm

The overall score for the road segment is the average of the individual scores.

2.3.2 Environmental Cracking Extent

The extent of environmental cracking is determined by the pecentage of road surface that is subject to cracking. Each 10m section of road is given a crack extent score in the range 0-3.

EXTENT
Score Area subject to cracking
0 no cracking
1 less than 5%
2 5% to 15%
3 more than 15%

The overall score for the road segment is the average of the individual scores.

2.4 Stripping

Stripping is the loss of aggregate from the surface, resulting in exposed binder and/or pavement.

Stripping3.jpg Paradise-Lane1.jpg Austroads-Stripping-1.jpg

The stripping score is determined by the pecentage of road surface subject to stripping. Each 10m section of road is given a score in the range 0-4.

EXTENT
Score Area subject to stripping
0 no stripping
1 less than 5%
2 5% to 10%
3 10% to 20%
4 more than 20%

The overall score for the road segment is the average of the individual scores.

2.5. Potholes

A pothole is a hole in a road pavement, frequently rounded in shape, resulting from the loss of pavement material under traffic.

Pothole1.jpg

The pothole score is determined by the pecentage of road surface with potholes. Each 10m section of road is given a score in the range 0-4.

Score Area containing potholes
0 no potholes
1 1% to 5%
2 5% to 10%
3 10% to 20%
4 greater than 20%

The overall score for the road segment is the average of the individual scores.

2.6. Pavement Patches

A pavement patch is pothole or other pavement or surface defect that has been repaired with premix.

Patches-01.JPG

The pavement patching score is determined by the pecentage of road surface that has been patched. Each 10m section of road is given a score in the range 0-4.

Score Area subject to cracking
0 no patches
1 1% to 5%
2 5% to 10%
3 10% to 20%
4 greater than 20%

The overall score for the road segment is the average of the individual scores.

2.7. Rutting

Rutting is the longitudinal vertical deformation of a pavement surface in a wheelpath, measured relative to a straight edge placed at right angles to the traffic flow and across the wheelpath, with a length/width ratio greater than 4:1.

Austroads-Rutting-3.jpg Kewdale-Rd-Shear-1.JPG

The standard measure for rutting is the maximum depth under a transverse 1.2m straight edge. The rutting score for a road segment is calculated by avergaging the maximum depth measurements for each 10m section of the segment, rounding down any depths over 25mm to 25mm.

For example, if the recorded maximum rut depths for a 100m road segment were; 10mm, 15mm, 35mm, 20mm, 5mm, 4mm, 50mm, 10mm, 9mm & 15mm.

The rutting score for the segment would be (10+15+25+20+5+4+25+10+9+15)/10 = 13.8

2.8. Asphalt Ravelling

Ravelling is the progressive disintegration of a pavement surface through loss of both binder and aggregate.

Ravelling is not currently used in calculating a road's SCI, but there is a ravelling field in MyData that can be used to store a road sections ravelling score.

Austroads-Ravelling-1.jpg Austroads-Ravelling-2.jpg Austroads-Ravelling-3.jpg
EXTENT
Level Degree Area Affected
0 Nil No Defects
1 Brand New Asphalt surface is brand new
2 New Surface < 3 years old Asphalt surface is reasonably brand new and there is very little evidence of fretting or fatigue to the surface
3 Aging Surface <10 years old Asphalt surface is showing signs of wear and tear, some associated fretting and wear/tear on the surface. Little evidence of any fatigue and or fine cracking
4 Aging Surface <20 years old Asphalt surface showing signs of age, fatigue, wear and tear on the surface. There is also evidence of localised or spread out pockets of saturation of fatigue with the loss of material. More evidence of fine cracking
5 Aging Surface >20 years old Asphalt surface is worn out, lots of wear and tear, typically the entire segment has pockets of fatigue saturation and loss of material. There is lots of wider cracking.

2.9. Pavement Defects

Pavement defects include, corrugations, shoving, depressions and unsucessful patches. The extent and severity of pavement defects is not currently used to calculate a road's SCI or PCI, but there are fields within MyData to record a score if it is known.

Dowd-St-Shear-Asphalt-3.JPG Cracking-and-Shoving1.JPG
SEVERITY
Level Description
Slight A Mean Displacement <25mm
Medium A Mean Displacement of 25 mm to Less than 50mm
Extreme A Mean Displacement of >50mm
EXTENT
Level Degree Area Affected
0 Nil No Defect Present
1 Negligible Evident <2% of Total Area
2 Minor Evident Between 2% To <5% of Total Area
3 Moderate Evident Between 5% To <15% of Total Area
4 Extensive Evident Between 15% To <50% of Total Area
5 Extreme Evident >50% of Total Area

Example
pavement-defects-example.png

Total the area of potholes, shoving, depressions and/or corrugation defects for the road segment
In this example defects = 3 x 2 + 3 x 1 + 2 x 2 + 3 x 4 + 1 x 2 = 30 m²

Road segment area = 100 x 6 = 600 m²

Extent of segment area affected = (21.39 / 600) x 100 = 5%

Looking at the Deformation Extent Table, 5% falls into rating 3 for this segment.

Now apply the most predominant severity level identified in the rated segment.

2.10. Condition Index Calculations

In MyData/MyPredictor it is possible to calculate overall condition scores for a road segments by applying a formula to the values in the various condition fields in the roads table.
This is part of what Assetic refer to as the "Asset Management Science".

2.10.1. Pavement Condition Index

When AARB collected condition information for the BRC sealed road network they suggested the following default weightings for calculating a road segment's Pavement Condition Index (PCI).

Measure Max Condition Score Weighting Multiplier
Urban Rural Short Urban Rural Short
Roughness 6 35 50 17.5 5.8 8.3 2.9
Rutting 25 10 10 10 0.4 0.4 0.4
Crocodile Cracking Severity 1 10 5 22.5 10.0 5.0 22.5
Crocodile Cracking Extent 0.5 20 10 10 40.0 20.0 20.0
Patches 0.5 25 25 40 50.0 50.0 80.0

This means:

Short Urban (< 150m): PCI = 2.9*Roughness + 0.4*Rutting + 22.5*Crocodile Cracking Severity + 20*Crocodile Cracking Extent + 80.0*Patches
Urban: PCI = 5.8*Roughness + 0.4*Rutting + 10*Crocodile Cracking Severity + 40*Crocodile Cracking Extent+ 50*Patches
Rural: PCI = 8.3*Roughness + 0.4*Rutting + 5*Crocodile Cracking Severity + 20*Crocodile Cracking Extent+ 50*Patches

It is proposed to use these default values for the time being, and to update them if and when we being to gain a better understanding of the peculiarities of BRC's road network.

2.10.2. Surface Condition Index

When AARB collected condition information for the BRC sealed road network they suggested the following default weightings for calculating a road segment's Surface Condition Index (SCI).

Measure Max Condition Score Weighting Multiplier
Urban Rural Short Urban Rural Short
Roughness 6 30 60 15 5.0 10.0 2.5
Other cracking Severity 3 10 5 10 3.3 1.7 3.3
Other cracking Extent 0.5 25 15 25 50.0 30.0 50.0
Stripping 1 5 5 10 5.0 5.0 10.0
Potholes 1 30 15 40 30.0 15.0 40.0

This means:

Short Urban (< 150m): SCI = 2.5*Roughness + 3.3*Other Cracking Severity + 50*Other Cracking Extent + 10*Stripping + 40*Potholes
Urban: SCI = 5*Roughness + 3.3*Other Cracking Severity + 50*Other Cracking Extent + 5*Stripping + 30*Potholes
Rural: SCI = 10*Roughness + 1.7*Other Cracking Severity + 30*Other Cracking Extent + 5*Stripping + 15*Potholes

It is proposed to use these default values for the time being, and to update them if and when we being to gain a better understanding of the peculiarities of BRC's road network.

3. Unsealed Roads

There are three main condition parameters that can be recorded against unsealed roads
Gravel depth, shape loss & cross section.

3.1. Gravel Depth

Gravel depth is the average depth of imported gravel pavement.

Score Gravel Depth
1 > 150mm
2 100mm to 150mm
3 50mm to 100mm
4 1mm to 50mm
5 No imported gravel

Gravel depth is the main indicator of when a road should be resheeted.

3.2. Shape Loss

Shape loss is a generic term for a number of defects including; rutting, scouring, corrugations, depressions, pothole, etc.

Earthco-Unsealed-Rutting-1a.jpg Earthco-Unsealed-Corrugations-Channels.jpg unsealed-potholes1.jpg
Score Area Affected
0 No defects
1 Less than 2% of total area
2 Evident Between 2% to <5% of total area
3 Evident Between 5% to <15% of total area
4 Evident Between 15% to <50% of total area
5 Evident >50% of total area

3.3. Cross Section

Score Description
1 Greater than 6% camber
2 0% to 6% camber
3 Less than 0% camber (no shape at all)

3.4. Resheeting Program Development

Unsealed Roads that have been identified as concern by the District Engineers during the year are assessed by a team of two inspectors. They are assessed visually and their pavement depth in determined.
Pavements with gravel depths of 50mm - 75mm or less are considered for resheeting, and prioritised on the basis of the number of properties they serve.

The visual inspection helps determine if maintenance grading is required and an assessment is also made about whether a low cost seal may be an option.

4. Footpaths

A footpath is a strip of concrete, asphalt, pavers, bitumen seal or crushed rock laid between the back of kerb and the property boundary (or elsewhere) for use as a path by pedestrians.

footpath-bar.jpg

Defects associated with footpaths include, vertical joint displacements, cracking, panel displacement due to tree roots and spalling.

BRC's Asset Management System has the ability to calculate an Overall Condition Index (OCI) for footpaths based on values for stepping, cracking, displacement, gravel loss, utility and pram ramp, but we are curently just giving footpaths an overall condition score in the range 0 to 6 and entering that value into the stepping field.

The table below shows the relationship between condition and remaining useful life that is used by our Asset Management System, and a description of the footpath's condition.

Condition RUL% WDV% Description
0 100 100 Brand new footpath in perfect condition
1 93 93 Very good condition - no visible defects
2 80 80 Good condition - only very minor defects visible
3 53 53 Average condition - a number of defects are visible, but is still quite serviceable
4 23 23 Below average condition - quite a few obvious defects are visible - substandard for CBD an other critical highly trafficked areas
5 12 12 Poor Condition - should be refered to capital works program for reconstruction
6 0 0 Very very poor condition - should be removed or replaced ASAP

In practice, the great majority of footpath defects are fixed one or two panels at a time under maintenance, and the overall condition scores for footpath segments rarely if ever drop below conditiion 4.

BRC-Footpath-Condition-0.jpg BRC-Footpath-Condition-1.jpg BRC-Footpath-Condition-2.jpg BRC-Footpath-Condition-3.jpg BRC-Footpath-Condition-4.jpg BRC-Footpath-Condition-5.jpg BRC-Footpath-Condition-6.jpg

5. Kerb & Channel

Kerb & Channel is a concrete or stone structure typically located at the edge of a road designed to provide road drainage, and as a barrier to prevent vehicles from leaving the road carriageway.

kerb-bar.jpg

Defects associated with kerb & channel include; rotation, vertical displacements, cracking, breaks, spalling, depressions & ponding.

SEVERITY
Level Description
Slight A Mean Displacement <25mm
Medium A Mean Displacement of 25 mm to less than 50mm
Extreme A Mean Displacement of >50mm
EXTENT
Level Degree Area Affected
0 Nil No Defect Present
1 Negligible Evident <2% of Total Length
2 Minor Evident Between 2% to <5% of total length
3 Moderate Evident Between 5% to <15% of total length
4 Extensive Evident Between 15% to <50% of total length
5 Extreme Evident >50% of total length

Example
kerb-and-channel-example.png

Total the length of concrete kerb and channel bays displaying distresses such as vertical displacement, depression, cracking, tilting and/or heaving for the kerb and channel segment; Noting that the extent measurement should extend to the areas where the cuts will be.
Depression = 6m; Vertical Displacement (lifting of kerb) = 3m; Cracking and Tilting = 6m (NB. As this section has already been identified as tilted, there is no need to identify the cracking defects in this area)

The total of kerb length defected = 15 m

Kerb and channel segment length = 100 m

Extent of segment length affected = (15 / 100) x 100 = 15%
Looking at the extent table above, 15% falls in condition rating 4 for this segment.

Now apply the most predominant severity of these defects.

Severity
Slight – defect ranges between 10 to 20mm Moderate – defects > 20mm

6. Concrete Pavements

6.1. Deformation

Measurement: Area
Units: square metres (m2)

deformation-bar2.jpg
SEVERITY
Level Description
Slight A Mean Displacement <25mm
Medium A Mean Displacement of 25 mm to less than 50mm
Extreme A Mean Displacement of >50mm
EXTENT
Level Degree Area Affected
0 Nil No Distress Visible
1 Negligible Evident <2% of total area
2 Minor Evident Between 2% to <5% of total area
3 Moderate Evident Between 5% to <15% of total area
4 Extensive Evident Between 15% to <50% of total area
5 Extreme Evident >50% of total area

6.2. Cracking

Measurement: Length
Units: metres (m)

linear-cracking.jpg
SEVERITY
Level Description
Slight Average Crack Width < 2mm
Medium Average Crack Width Between 2mm and 5mm
Extreme Average Crack Width > 5mm
EXTENT
Level Degree Area Affected
0 Nil No Defect Present
1 Negligible Evident <2% of total length
2 Minor Evident Between 2% To <5% of total length
3 Moderate Evident Between 5% To <15% of total length
4 Extensive Evident Between 15% To <50% of total length
5 Extreme Evident >50% of total length

6.3. Joint Sealant

Measurement: Length
Units: metres (m)

EXTENT
Level Degree Area Affected
0 Nil No Defect Present
1 Negligible Evident <2% of total joint seal length defective
2 Minor Evident Between 2% To <5% of total joint seal length defective
3 Moderate Evident Between 5% To <15% of total joint seal length defective
4 Extensive Evident Between 15% To <50% of total joint seal length defective
5 Extreme Evident >50% of total joint seal length defective

7. Acknowledgments

The photos used in this document have been sourced from a number of places, including the "A Guide to the Visual Assessment of Pavement Condition". published by Austroads in 1987. Clicking on a photo, will open a page explaining more about the photo and from where it was sourced.

8. Attachments

Unless otherwise stated, the content of this page is licensed under Creative Commons Attribution-ShareAlike 3.0 License