Micro-Trench Reinstatement Techniques
www.stirlinglloyd.com
safetrack®
�You�re not putting that in my road�
Micro-trench reinstatement
Presented By: Mike Harper – Development Director, Stirling Lloyd.
NextGen 12 - London
Micro-Trench Reinstatement Techniques
www.stirlinglloyd.com
safetrack®
Micro-trenching Reinstatement
• What is the problem?
• Why Micro-trench?
• Limitations of traditional
reinstatement
• Incorrect approaches
• What�s required?
• The Safetrack approach
• Step by step examples
Micro-Trench Reinstatement Techniques
www.stirlinglloyd.com
safetrack®
• Micro trenching not covered by the new �yellow book�
• Little existing knowledge on how to reinstate micro trenches
• Councils object on grounds of • You�re cutting my road in half
• No specification
• Water ingress into the road
• No HAPAS approval
• Can�t compact asphalt in a slot
What is the problem?
Micro-Trench Reinstatement Techniques
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Why Microtrench? 1 - It�s Much Faster
! 4 to 5x faster than open trench
! 600 ln m per day on a trunk route (achieved in Shetland)
! Less disruption to the public
! Less traffic congestion
Getting FTTP to 90% of UK addresses could mean 247,500 km of fibre installation!
Micro-Trench Reinstatement Techniques
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Why Microtrench?
2 - Lower Environmental Impact
! Significantly less waste created to be disposed of
! Less new materials imported
! Fewer truck movements because of the above
! Less traffic congestion because of fast turnaround
! All this means lower CO2
Micro-Trench Reinstatement Techniques
www.stirlinglloyd.com
safetrack®
Why Microtrench? 3 - Lower Cost
! Lower costs because of speed / waste & new material
! Lower long term maintenance costs if you get the reinstatement right (no secondary compaction / sunken trenches)
! Less damage to the highway asset (shallower – less impact on sub-base / surface course and services)
Micro-Trench Reinstatement Techniques
www.stirlinglloyd.com
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• Traditional reinstatement materials (macadam & asphalt) were not designed for this.
• Can�t place / compact hot asphalt / macadam in a 20mm wide slot
• Pouring neat bitumen is not the solution (no strength or skid resistance)
• Trying to tamp cold lay asphalt? Early failure due to lack of compaction
• Most methods will let water into the pavement!!
What is the problem?
Micro-Trench Reinstatement Techniques
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1. Cement grout to the surface Not flexible No bond to asphalt Cracking / water ingress Slow strength gain
2. Epoxy Mortar
Not flexible Long cure time = greater disruption Cracking / water ingress
2. Cold lay macadam
Needs adequate compaction to achieve cohesion Little bond to cut asphalt edges Ineffective seal – water ingress Lack of cohesion
Incorrect approaches and why?
Micro-Trench Reinstatement Techniques
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• Most recent advice note from DCMS – the Department for Culture, Media & Sport - outlines current best practice
• This can be complied with and is a good start
• Key drawback is reinstatement in the asphalt layer only at depths that exceed the asphalt depth in evolved roads
What current advice is there?
Micro-Trench Reinstatement Techniques
www.stirlinglloyd.com
safetrack®
• A fluid material that will penetrate - needs no compaction
• High bond strength to the cut asphalt
• Supports the cut edges of the asphalt
• Compatible flexibility with asphalt
• No shrinkage & waterproof seal
• Skid resistance
• Dimensional stability under traffic
• Fast return to service
• BBA / HAPAS approval
So what do we need to reinstate a micro-trench effectively?
Micro-Trench Reinstatement Techniques
www.stirlinglloyd.com
safetrack®
• Materials designed for highway use
• Safetrack is fluid & self compacting
• Cold applied – safe to use
• No �site mix� – Factory batched (QA)
• Dimensional stability – can�t be �trafficked out�, rut or sink (no secondary compaction)
• Bond strength > cohesive strength of asphalt (bonds the road back together)
• Waterproof and seals the road
• Skid resistant
• No glare
• BBA / HAPAS approved
The �Safetrack� approach
Micro-Trench Reinstatement Techniques
www.stirlinglloyd.com
safetrack®
Additional benefits
• No specialist equipment = quality installation from every team, all the time.
• No heating = no risks to public and operatives + less CO2.
• Safetrack MTI indicator layer = reduces risk of accidental damage in future by using yellow below the surface
• Doesn�t damage the fibre installation
• Permits removal / reinstatement of duct if required.
The Safetrack approach
Micro-Trench Reinstatement Techniques
www.stirlinglloyd.com
safetrack®
Successful Safetrack Microtrench Installations
South Wales – Safetrack approved for use by the Welsh Assembly for microtrenching on trunk roads in 2009
Shetland – Safetrack products successfully used over last 3 years – now on Phase 4.
Galway – Safetrack products used over last 2 years – now in Phase 2.
Bournemouth – multiple products tried without success. Safetrack products were the only ones regarded successful by Bournemouth CC.
Micro-Trench Reinstatement Techniques
www.stirlinglloyd.com
safetrack®
Microtrenching
Step by step through the process
Micro-Trench Reinstatement Techniques
www.stirlinglloyd.com
safetrack®
Cutting
• Cutting machine type is very important
• Match the duct to the cut size
• Avoid oversize cutting
• 20mm cut / 16mm duct is ideal where possible
Micro-Trench Reinstatement Techniques
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• Dry cutting is a clean process - no slurry waste from wet cutting
• Vacuum extraction �hoovers� dust from the slot
• Cutting depth is constant (150mm here)
• Overbreak along the cut is minimal
Cutting
Micro-Trench Reinstatement Techniques
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safetrack®
• Vacuum extraction avoids dust
Cutting
Micro-Trench Reinstatement Techniques
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safetrack®
Cutting
• Resultant cut is even width
• Minimal damage to surrounding asphalt
• Minimal work area
• Fast, clean and accurate
Micro-Trench Reinstatement Techniques
www.stirlinglloyd.com
safetrack®
Drying
• Safetrack drying lance removes any residual dust
• Dries the cut asphalt faces using air and / or heat if required
• A clean dry asphalt face = high bond strength and a good seal
Micro-Trench Reinstatement Techniques
www.stirlinglloyd.com
safetrack®
• Protective foam strip into the bottom of the micro-trench
• Microduct – with or without fibres – is installed
• A protective foam strip is applied over the duct
• The micro-trench is now ready to be permanently reinstated
Installation
Micro-Trench Reinstatement Techniques
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• Installing Safetrack Crack Infill into the micro-trench
• Cold process – simple and accurate placement
• Can use yellow indicator below the surface to avoid future damage
• BBA / HAPAS approved product
Reinstatement
Micro-Trench Reinstatement Techniques
www.stirlinglloyd.com
safetrack®
• Yellow first pass up to 10mm from the surface
• Black capping layer with embedded aggregate for skid resistance
Reinstatement
Micro-Trench Reinstatement Techniques
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safetrack®
• Safetrack Overbanding black surface layer
• Aggregate overscatter
Reinstatement
Micro-Trench Reinstatement Techniques
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safetrack®
• Process train approach moves continuously along the road
• All the processes are in this image
• Rapid cure of the reinstatement means minimal traffic management behind the works
• 600 ln m per day complete installation
Reinstatement
Micro-Trench Reinstatement Techniques
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safetrack®
• Completed micro-trench
• Fibre duct installed at 150mm deep
• Safetrack Overbanding permanent reinstatement
• Up to 600 ln m per day completed and returned to service same day (Shetland rural roads)
Reinstatement
Micro-Trench Reinstatement Techniques
www.stirlinglloyd.com
safetrack®
• Traditional trench dig would be 5x slower
• Would create much more disruption for residents and road users
• Uses far more material and creates much more waste
• Far higher carbon footprint
• Much greater damage to the road or pavement asset and likely requirements for more long term maintenance (secondary compaction etc)
• We need micro-trenching but we need to do it right.
But we�ve always done it this way ……
Micro-Trench Reinstatement Techniques
www.stirlinglloyd.com
safetrack®
For more information contact us:
t: 01565 633111
m: 07976 517200
w: www.highwaymaintenanceproducts.co.uk
Questions?