Monitoring
Markings should be regularly monitored to ensure that they do not fall below the specified
retro-reflectivity level and therefore recommended safety levels.
All road markings will deteriorate over time, due to general weathering and the number of wheel passages.
For the UK , using BSEN 1436 and TD26/04, the recommended intervention level for
the replacement of markings is 80mcd/ m_lx, while the investigatory level is anything less than 100mcd/ m_lx.
In America the minimum standards are higher, the ASTM (American Society for Testing and Materials) a respected standards
body in the US, recommends a minimum of 250 mcd/m_lx for horizontal road marking "to ensure that adequate conspicuity
for the driver at night is provided by newly applied markings."
Objective measurement of the performance of road markings can be carried out using retro-reflectometers,
to ensure markings maintain optimum performance creating a safer network.
In the UK, the rest of Europe and North America, retro-reflectometers use a 30-metre geometry,
a change from the old 15-metre geometry. This change was made as the new standard focuses on the Drivers NEEDS, 30m geometry is deemed to be a better
replication of what the driver actually sees.
There are two main categories of retro-reflectivity testing equipment, static and mobile those most
commonly used in the UK are detailed below, however there are other monitoring systems available.
Static
LTL 2000 & ZEHTNER HAND HELD RETRO-REFLECTOMETERS
Static method testing is ideal if you have a small isolated area of markings to test.
The machine is placed over the line a light source takes a retro-reflectivity and luminance reading,
the result of which is displayed in an LCD on top of the machine.
A button can then be pressed to produce a printed report, in the form of a till receipt.
Many laboratories throughout the UK own this type of testing equipment.
However, it does have its limitations:
- If you have several kilometres to test. This method is very time consuming
- The line needs to be cleaned prior to testing
- Two people are generally required
- If testing on a busy road Traffic Management is required
- Information collated on site then needs to be reported on manually
Mobile
ECOYDN
A mobile retro-reflectometer developed and designed by the LCPC in France, equivalent to the UK’s TRL.
(Transport Research Laboratory)
The LCPC, spent many years researching and developing, Ecodyn and now have over 20 machines world wide
continually, checking markings and prioritising maintenance work.
The RSMA use this system to carry out the Annual Road Markings Survey, "Up to the Mark?"
A Mobile System can:
- Record retro-reflectivity readings while travelling at up to 70mph
- No Traffic Management requirements
- No cleaning of lines is carried out prior to the survey. The survey records what the driver sees.
This may highlight a maintenance issue of cleaning rather than the replacement of lines.
- Measurements are taken from the line every 40cm’s and averaged out over 1m
- Results recorded onto floppy disk, allowing for easy access. Excel compatible.
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