Installation
Maintenance
HDPE Duct

INSTALLATION

Consultation with the Cities/Municipalities Streets and Engineering Department describes proposed location, description and depth of the network including proposed timetable for commencement and completion of the works and the dates and times during which the Company proposes to carry out such works. Further consideration will also be given to accommodate roadway or footway improvement schedules and may assist with optimal depth determination.
Minimum depth required within NRSWA, New Roads and Streets Work Act 1991, is 20mm into unbound layer. Lite Access recommends target depth of 25cm (minimum) in hard infrastructure and 30cm (minimum) in soft infrastructure. Actual depth may be determined by the materials found within the structure and depth of third party plan.
Most deployments are engineered to be placed in a location and depth whereby the opportunity of network compromise is virtually non-existent. This may include the transition between gutter pan and road surface, middle of road, 1m from edge of roadway, etc. and will be determined in consultation with governing authorities.
The microduct is laid directly into the 17mm – 30mm micro-trench, surrounded by a layer of dry sand, back filled to underside of asphalt with either pea gravel or flowable non-shrink grout (as per Geotechnical Recommendations – June, 2012) Final reinstatement varies depending on governing authorities however Lite Access recommends the use of Infrared as the final reinstatement process. Infrared creates a seamless reinstatement whereby the opportunity of water ingress is completely non-existent.
Any cable with non-current carrying metal components must be grounded at the building entrance or as soon as feasible. The 2002 NESC, section 31, under General Requirements Applying to Underground Lines and sub-section 315, Communications Protective Requirements, state that cable must be grounded if the following conditions apply:

  • Lightning
  • Contact with supply conductors with voltages exceeding 300V
  • Transient rise in ground potential exceeding 300V
  • Steady –state Induced voltage of a level that may cause personal injury
Lite Access’ MicroDuct Technique provides for up to 288 fibres in a single deployment (depending on microduct configuration – greater than 288 strands is also available). Depending on current requirements, clients are now able to purchase what is immediately needed. No longer does a client have to spend large amounts of capital for product and services that may never be used. Our future-proof solution enables clients to control the growth of their network by allowing additional fibre to be blown at any time.
LAT’s fibre solution was designed to integrate with any type of existing infrastructure and technology. Lite Access’ fibre products are color coded in accordance with TIAIEIA-598A, “Optical Fibre Cable Color Coding”, and terminate into traditional splice enclosures most typically used within the Telecom Industry. Use of non-proprietary, common access chambers, handholes, manholes etc. enables integration of new and existing networks as well as availability and acceptability of product within cities and Municipalities. LAT’s microduct is also fully compliant with the requirements of CEI/IEC 60794-3-10, International Standard for Outdoor Cables enabling direct bury and aerial application use.
Based on the life of the infrastructure in which the cable is placed, we anticipate a lifespan of greater than 20 years. Another consideration is that the cable can be completely replaced without affecting customers (provided that redundancy is deployed), giving the network a potentially endless life.

MAINTENANCE

No damage has been experienced to Lite Access’ networks to date. Consultation with local authorities include consideration of existing route conditions including future build possibilities, road improvements etc. enabling the design and engineering of the network in the safest and least vulnerable route. Once installed, detailed documentation including as-built drawings will be in the possession of the local authorities and client.
Subscribing to ‘call before you dig’ services will prevent the majority of events. Also some education may be required for city maintenance teams who deal with footway and road repair to ensure detailed documentation and as built drawings have been obtained and properly analyzed. ‘Man-made’ or events having an identical impact on any type of deployment methodology – namely, related to utility maintenance and construction not following the correct procedures and checking registered ‘as-built’ documentation may be possible.
In addition to as-built drawings and typical placement of the network between the gutter pan and road, LAT’s microduct contains an aluminum layer or tracer wire that can be used to locate the damaged cable. An OTDR (Optical Time Domain Reflectometer) can also be used to locate damaged fibres.
In most cases, if the fibre has been damaged, the microduct network has also been compromised. Using specially designed connectors providing an air tight and water tight connection a new section of microduct is connected. The fibre can then be either spliced at the break location or the broken strands blown out and new fibre blown in.
Liteacccess’ microduct technology was designed as a one piece conduit system containing full water barrier protection and conforming to or exceeding stringent crush test and tensile load parameters. Placement of the network in existing expansion joints such as gutter pan and road, and at depths within the unbound layer provides further protection from varying external forces.

HDPE DUCT

The Standard Dimension Ratio relates the outside diameter (OD) of the duct to its wall thickness (t),
so SDR = OD / t.
Note that low SDR means very strong duct. Higher SDRs mean thinner wall, more flexible, less strong. Note that different OD ducts that have the same SDR will tend to have similar flexibility and crush performance.
All tube or duct will have a recommended bending radius limit, such that installing tighter than this can increase the risk of kinking (maybe not immediately, which should be remembered) or just less comfort for cables etc being installed later. Our generic spec MHT 582 gives recommended MBR data, as do our other specific datasheets.
Lite Access Technology ducts are made from high quality HDPE with excellent tensile behaviour. Ducts can normally be stretched to 14MPa or 15MPa stress levels and still recover closely to their original dimensions. We recommend lower stresses than this during installation, in order to reduce the amount of excess duct length required for full relaxation. Staying at say 2MPa permits fast installation, relaxation and cropping times by minimising elongation.
Example: 2MPa = 2 newtons per square mm of cross-section, eg for a 25/20 duct, the csa would be 177sqmm, and so 2MPa represents 2 x 177 = 354N load (35kg). You could safely use twice this tension, but would need to allow more relaxation length and time.
When you accidentally stand on a duct, you do not want it to become useless for the job. And standing on a duct could mean a load of 80kg on a length of just 12 or 14cm. Ducts with SDR 10 or 11 are very typical and these can easily withstand such compression loads. The compression causes typically only 10% or 15% reduction in diameter, and when the load is removed, the duct begins a rapid recovery towards its original dimensions. Lite Access Technology ducts are very resilient and forgiving.
Polyethylene is one of the plastic industry’s top performers in terms of length of service. PE is virtually inert and does not suffer from rotting, fungus or oxidation like wood or metal. And it is not prone to breakage due to impact, fatigue (repeat bending) or overload. That is one reason why cracked and broken IRON pipelines have been replaced all over the world by PE pipelines. They are expected to last for 25 or 50 years without serious deterioration. They out-perform the iron by being more suitable for the job.
PE has excellent chemical resistance properties and is able to resist most common contaminants in underground deployments. Please consult us if you have specific chemicals at your installation site.
Buried ducts generally see only low and very constant temperatures, around 10°C. The normal maximum installation temperature for our HDPE ducts is 40°C, since compression performance reduces at elevated temperatures. Low installation temperatures down to -40°C are permissible although the product may become notably stiffer and more difficult to manipulate. Note that at very low temperatures, we recommend using higher min bend radius. See the relevant data sheets.