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An Investigation on Micro-Trenching Technology for FTTH Deployment

  • Author / Creator
    Hasanuzzaman, Md.

  • The immense demand for Internet-based information sharing, entertainment, and communication services has dramatically augmented, and the existing copper network cannot meet this unprecedented bandwidth need. Upgrading copper-based networks to high capacity fiber optic (FO) networks involves high costs for deployment and has a negative impact on the existing infrastructures, surrounding environment, and nearby communities. Compared to other traditional methods, micro-trenching technology (MTT) in urban areas can facilitate a quick, easy, cheap, and low impact fiber-to-the-home (FTTH) deployment alternative. Communication providers (CPs) know MTT’s potential, and they have completed several MTT projects in different countries. However, since MTT does not yet have any accepted construction standard, a poor quality installation is likely to be damaged or to damage the pavement. Severe weather conditions (e.g., freeze and thaw cycles) may cause further damages. Additionally, changes in weather conditions may yield significantly different backfilling performances. Therefore, before organizing a large-scale project, MTT needs to be evaluated in those conditions in order to ensure the durability of installations while maintaining the pavement’s integrity, longevity, and aesthetic view. To evaluate the performances of MTT in northern climates, two pilot installations using vertical inlaid fiber (VIF) technology and surface micro cabling inlay (SMCI) technology were installed in Edmonton, Alberta, Canada and monitored for over two years using optical time domain reflectometer (OTDR), ground penetrating radar (GPR) technology, and visual inspections. The OTDR results showed that the span losses were in allowable limit despite of sharp bends and traffic and weather distresses in the shallow-depth installations. The GPR and visual monitoring results from both installations showed significant vertical movements of conduit/cable and premature failures of backfilling materials, and a comparison of these installations concluded large differences in movements and failures because of their discrete construction and material specifications. To improve the backfilling and overall performance of MTT, this study proposes a modified backfilling by stabilizing the conduit with a quick-setting and non-shrink grout in the base layer, while avoiding any damages that may occur during the road reconstruction and rehabilitation operations. Setting time, conduit coverage, flowability, and compressive strength tests were conducted in the laboratory to achieve conduit stabilization. All grouts had acceptable material properties, but only one was the most cost-effective. Considering the micro-trenching applications at freezing temperatures, the conducted modified compression test results showed that after full curing, the compressive strength of the grout was significantly reduced. In the proposed backfilling, it is suggested that a cold mix asphalt (CMA) to be applied on top of the grout in the asphalt layer of the pavement. The CMA-1 (CMA) used in the VIF installation had premature failures, for instance, ravelling, cracking, edge disintegration, and settlement. In addition to the CMA-1, 11 other widely used CMAs, including proprietary and conventional mixes, were collected to test in the laboratory. By following sound construction techniques for the backfilling of micro-trenches, a high quality CMA, may provide not only good workability but also sufficient durability. The results of modified Marshall Stability and flow, indirect tensile strength, cohesion, and adhesiveness tests illustrated a high variation in material properties. Among 12 mixes, some of the CMAs would be good for patching and a few of them would be good for backfilling the MTT.

  • Subjects / Keywords
  • Graduation date
    Fall 2016
  • Type of Item
    Thesis
  • Degree
    Master of Science
  • DOI
    https://doi.org/10.7939/R3FN11331
  • License
    This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.