UKPMS Comparability Testing
Accredited UKPMS Systems
The 3 Tranches of UKPMS Functionality
· Tranche 1
· Tranche 2
· Tranche 3
Rules and Rule Sets
Best Value Performance Indicators
UKPMS Condition Surveys
· Coarse Visual Inspection
· Detailed Visual Inspection
· SCANNER Surveys
· Machine-Measured Rutting
UKPMS Location Referencing
· Section Referencing
· Chainage and Feature Referencing
· Cross Section Position Referencing
UKPMS Condition Surveys
Coarse Visual Inspection
The Coarse Visual Inspection or CVI, is intended
to be a coarse, rapid survey, usually carried out from a slow-moving
allows a large part of a highways authority’s road network
to be assessed each year.
CVI is the standard survey used to produce
the Best Value Performance Indicators on the condition of local
authorities’ roads as
required by the government, and which allows comparisons to be
made between authorities on the basis of the overall condition
of their carriageways.
A CVI survey is normally undertaken from a
slow moving vehicle, using the “simple” cross-section
position method, where the carriageway is assessed as a whole,
and kerbs, footways and
cycletracks are separately inspected for the left and the right
of the carriageway.
Detailed Visual Inspection
The Detailed Visual Inspection or DVI, is a more comprehensive
survey than the CVI, with defects identified by a larger number
of more detailed classifications. The DVI is a walked survey, and
is typically targeted at lengths already identified as defective
and potentially in need of treatment either by the CVI, or from
some other sources of information.
The DVI records measured areas or lengths for a wider range of
more closely defined defects (than for CVI), aggregated within
short sub?sections, 20 metres in length by default. The defects
collected for DVI are generally defined to a closer level of detail
than CVI. In order to ensure broad consistency between the two
surveys a single CVI defect is normally equivalent to a number
of DVI defects.
It is intended that DVI is used where more detailed information
is required to support and validate treatment decisions and scheme
identification, supplementing CVI data; it may also be used on
a cyclical basis for parts of the network where a more detailed
routine visual assessment is required or where driven surveys are
If DVI surveys are to be used to produce Best Value
Performance Indicators, then they should be converted to CVI-equivalent
data using the UKPMS Conversion Software.
SCANNER Surveys are high-speed surface condition
surveys, based on the Highways Agency TRACS Contract and developed
to be suitable for the Principal Road Network. SCANNER collects
the following data:
- 3-Dimensional Spatial Co-ordinates
- Road Geometry
- Survey Speed
- Longitudinal Profile
- Wheelpath Rutting
- Texture Profile
Additionally, measures of edge condition and transverse
uneveness are being developed.
Further information is available in the SCANNER Specification.
It is intended that traffic speed surveys will be further developed
for used on local roads over the coming years.
SCRIM (Sideway-force Coefficient Routine Investigation Machine)
was introduced in the early 1970s to provide a method of measuring
the wet skidding resistance of the road network. The normal testing
speed for the machine is 50km/h and skidding resistance values
for the nearside wheel track only (usually the location of the
lowest skidding resistance) are generally recorded as the average
for each 10m section.
The principle of the machine is that a test
wheel, mounted mid-machine in line with the nearside wheel track
and angled at 20° to
the direction of travel, is applied to the road surface under a
known load. A controlled jet of water wets the road surface immediately
in front of the test wheel, so that when the vehicle moves forward,
the test wheel, whilst rotating freely in its own plane (thus allowing
uniform wear on its test wheel tyre), slides in the forward direction
on a wet road surface. The force generated by the resistance to
sliding is related to the wet skidding resistance of the road surface
and measurement of this sideways component allows the sideway-force
coefficient (SFC) to be calculated.
SCRIM surveys are processed differently from other
surveys types within UKPMS, in that they make use of “Functional”
defects. These defects always prompt treatment if they are below
the target threshold. The treatment that is suggested will depend
upon what other defects, from other surveys, exist at the same location.
The Deflectograph is used to assess the structural condition
of flexible and flexible composite pavements. It works on
that as a loaded wheel passes over the pavement, the pavement
deflects and the size of the deflection is related to the
strength of the
pavement layers and subgrade.
The Deflectograph is an automated deflection measuring system.
It is a fully self-contained lorry-mounted system, whereby measurements
of deflection are taken at approximately 4m intervals in both wheelpaths
while the machine is in motion.
For both survey types, but especially for CVI surveys, although
it is possible to assess Wheel Track Rutting manually, either using
a straight edge and wedge or depth measure for DVI surveys or by
visual assessment for CVI surveys, the preferred option is to measure
rutting using machine-based options, either as part of a CVI surveys,
or as a separate rut survey.. Two special survey types of Machine
Collected Rutting for DVI (DRUT) and Machine Collected Rutting
for CVI (CRUT) have been created have been defined to support the
loading and processing of such with visual surveys. Appendix 11
of the UKPMS Visual Survey Manual gives more details. This is recommended
both on grounds of accuracy, and for DVI surveys, safety, since
it removes the need to walk onto the carriageway.