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Buried Duct Network for Upgrading Utility Cables – Recent Field Trials

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Presentation on theme: "Buried Duct Network for Upgrading Utility Cables – Recent Field Trials"— Presentation transcript:

1 Buried Duct Network for Upgrading Utility Cables – Recent Field Trials
Outside Plant Consulting Services, Inc. P S C Buried Duct Network for Upgrading Utility Cables – Recent Field Trials Dr. Lawrence M. Slavin Outside Plant Consulting Services, Inc. 2009 AASHTO Right of Way & Utilities Subcommittee Conference Oklahoma City April 20, 2009

2 Sponsor Funding: US Department of Transportation Technical Oversight:
FHWA Turner-Fairbank Highway Research Center

3 Objectives & Goals Short-Term: Long-Term:
Develop improved method of buried construction for utility cables (telecommunications, CATV, power) Long-Term: Avoid damage to roads and transportation systems Minimize proliferation of utility poles

4 Background

5 Cable Construction Methods
Overhead Utility Poles Below ground Underground conduit Direct-Buried P S C

6 cables placed directly in trench

7 Direct-Buried Philosophy
Cables directly placed in trench Robust cable designs electrically insulated (power, ...) waterproof mechanical protection (armor, …) Sized for “ultimate” future needs P S C

8 Direct-Buried Philosophy
Typically, no convenient means of cable addition, replacement or upgrade* * Sometimes a duct is provided in trench by a utility, but is not a uniform practice across all utilities and regions, or necessarily done in the most cost-effective manner

9 Direct-Buried Philosophy
Does it usually work (successful) ? Often (in use for several decades) Does it always work ? No new technology exhausted capacity cable degradation or damage new service providers P S C 2

10 Direct-Buried Philosophy
THUS Cable additions require aggressive construction (open-cut trenching, directional drilling, …) Possible damage to roads, property, utilities, ... Safety hazards P S C 2

11 Buried Duct Network (BDN)

12 Benefits For buried facilities (requiring future upgrades, maintenance, …), avoids Road damage (road cuts, ...) Corresponding traffic delays Damage to buried lines (gas*, electric,…) Damage to Intelligent Transportation System (cables, …) P S C * e.g., US DOT - Office of Pipeline Safety

13 Benefits Consistent with AASHTO & FHWA Recommendations*
Belowground lines Access and Upgradability Joint Usage of Infrastructure & Facilities * A Policy for Accommodating Utilities Within Highway Right-of-Way, A Policy on the Accommodation of Utilities Within Freeway Right-of- Way, Guidance on Sharing Freeway and Highway Rights-of-Way for Telecommunications, Highway/Utility Guide.

14 BDN Concept/Design Hybrid system; combines
Advantages of underground conduit (upgradability) with Advantages of direct-buried construction (low cost) P S C 2

15 BDN Concept/Design Specify standard, optimized, cost-effective Buried Duct Network: Initially installed distribution cables are selected, sized and directly-buried in joint-use trench, following present recommended (cost-effective) practices Two large diameter (e.g., 4-in.) main distribution ducts, initially vacant, accessed at common handholes, also placed as an overlay in the same joint-use trench

16 BDN Strategy* Add minimum duct network for insurance for atypical (but not uncommon) cases when need upgrade Consistent with shared/joint-usage philosophy Space-efficient Cost-effective P S C * Does not apply to applications that warrant full-scale underground conduit systems (e.g., banks of conduits, manholes, …) 2

17 BDN Detail patent pending 2
Note: for thoroughfare application, possibly omit service lines common (joint) service trench utility terminals/equipment/hardware (power, telephony, CATV) three individual service ducts power handhole tele CATV two vacant large (e.g., 4-in.) ducts through handhole common (joint) main trench along ROW initial distribution cables (direct-buried, w/o duct) initial primary power distribution cables (direct-buried, w/o duct) patent pending BDN Detail 2

18 (Nominal 2 ft. wide x 3 ft. long x 36+ inches deep)
Not to Scale 6 knockouts (both sides) flared sides (avoid uplift -- frost, duct, …) lid mouseholes (e.g., 4-in. duct) bottomless patent pending (Nominal 2 ft. wide x 3 ft. long x 36+ inches deep)

19 Direct-Buried Initial Cables plus Vacant Main Ducts thru Handhole
initial distribution cables (direct buried, w/o duct) e.g., communications (telephone, CATV) handhole two vacant main ducts (HDPE, PVC, …) (future distribution cables) e.g., power (primary and/or secondary) express duct (alternative) cut/sealed duct same (joint) trench patent pending Direct-Buried Initial Cables plus Vacant Main Ducts thru Handhole 2

20 BDN Concept/Design Main distribution ducts are initially vacant
Future Use of main distribution ducts efficiently allocated, as necessary (telephone, CATV, power) Individual, smaller diameter, service wire ducts are routed from terminals to residence or small business, to provide protection for initial service wires, and facilitate future upgrade or replacement P S C 2

21 BDN Concept/Design Handhole NOT intended for routine maintenance (no terminals, splices, ... ) - - avoids exposure of communications workers to high voltages Accessed only if and when the need arises for future addition of cable(s) P S C 2

22 Alternatives

23 P S C 2

24 P S C 2

25 P S C 2

26 Phase I (Feasibility) 6 Months

27 Phase II (R&D) 24 Months 2

28 Phase II Effort Develop design, construction, maintenance, and management guidelines and practices ASCE Pipeline Division “ASCE Manual of Practice for Belowground Pipeline Networks for Utility Cables” Anticipated availability Summer 2009 P S C 2

29 Phase II Effort Ensure availability of prototype hardware for future applications, field trials, ... Handholes (load ratings, ...) Ducts, conduits Security system (locks, …) ….. P S C 2

30 Polymer Concrete (Quazite®)
Handholes (TIER 15) Polymer Concrete (Quazite®) 2

31 Handholes (“20K”) HDPE (Pencell Plastics) 2

32 Phase II Effort Arrange appropriate full-scale field trials
Permanent installation e.g., 1 kft Road, highway, residential, … Identify & address various issues Leverage for future introduction into utility and transportation industry practices P S C 2

33 Phase II Effort Completed or planned field trials
Arlington, Texas – November 2008 Monroe, NC – March 2009 Danvers, MA – June 2009 P S C 2

34 Monroe, NC Road Widening SR1223 (NCDOT)
Moving Verizon and Time Warner Cable Outer edge of ROW Tier 15 handholes (NC DOT) Open-cut trenching Conventional PVC (adhesive joints) 1 kft (<800 ft.) Conduits (and innerduct) for future (and initial) cables 2

35 Monroe, NC Thanks, Gus !

36 All conduits plugged at all exposed ends
Handhole Locations for Verizon BDN /Time Warner Installation (Monroe, NC) 30” x 48” x 36-in deep handholes (Quazite PG3048) 36” width trench Verizon equipment/pedestal  390 ft.  330 ft. two 4-in. conduits (e.g., Schedule 40 PVC) 2 Time Warner Cable innerducts (outside handholes) Time Warner Cable mini-vault increase trench width in vicinity of handholes initial Verizon cables through one conduit All conduits plugged at all exposed ends Not to Scale

37 two 4” (Verizon) conduits pull rope
Trench Cross-Section for Verizon BDN /Time Warner Cable Installation (Monroe, NC) surface two 4” (Verizon) conduits pull rope  36” fiber cable + pull rope fiber cable pr copper cable (+ vacant path ?) 36”+ two 2” (Time Warner Cable) innerducts, including tracer wire Not to Scale

38 Martin Luther King, Jr. Blvd (SR 1223)

39 Trenching & Conduit/Handholes

40 Installed BDN Conduit & Handholes

41 Time Warner Cable Direct-Buried Innerduct

42 Installed Innerduct

43 Backfilling & Compacting

44 Backfilling & Compacting

45 Finishing video

46 Finishing

47 Phase II Effort Implementation issues Ownership
Joint-usage agreements (compensation, …) Road and construction permits ... P S C 2


49 How You Can Help (Permits, ...)
Encourage (require ?) use of upgradable networks (BDN, other, ...) Stricter specifications Uniformity (across states, ...) P S C 2

50 How You Can Help (Permits, ...)
Suggestions Existing related efforts ? Individual states ? Nationally ? How to proceed ? P S C 2

51 Thank You ! P S C 2

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