Placing G.fast vs. FTTH in Brownfield Construction

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Many Telcos are now comparing the cost of placing fiber-to-the-home (FTTH) vs. G.fast in brownfield construction. FTTH is common in greenfield construction. Placing fiber in subdivisions that are already served with paired copper networks, both aerial and buried, is an arduous task and it is extremely expensive. G.fast is, for most, a viable, less expensive alternative.

G.fast is a digital subscriber line (DSL) protocol standard for local copper loops shorter than 1,600 feet (500 meters) offering speeds over 100 megabits. G.fast uses fiber to existing buried pedestals or aerial terminals, and then uses existing copper to the residence, and uses existing inside copper wire to and in the residence.

Buried
Buried fiber-to-the-home is a given in greenfield construction but cooperation between utilities is necessary to prevent damaging each other’s utilities when placing. Greenfield construction has its own political problem when it comes to the general contractor or municipality who determines which Telco or cable company gets the rights to placing the fiber.

Placing buried fiber in brownfield construction depends on the subdivision. If original utilities were placed at the correct depth in the proper area of the easement, then fiber can be easily installed without damage to existing utilities. If the buried easement is already cluttered with the existing Telco copper, distribution power, CATV, and sometimes gas utilities, then these must be located before digging.

Locating is very difficult in congested areas requiring low frequency signal (less than 1Khz) which requires an independent ground at the far end of the locate. This takes time, and, because of that, many locate technicians shift to high frequency which spills on to other utilities ending up with a miss-locate.

In every instance, what’s not marked has to be dealt with. The utility locating service typically marks only the public utilities including the electric, gas, phone, and cable.

Other items that typically won’t be located include:
• landscape irrigation
• water and sewer service lines to house
• low-voltage landscape wiring
• septic systems
• any other gas or wiring that has been added (i.e., yard light wiring, gas lines to grills/fire pits, etc.)

Attempting to trench in the fiber cable is extremely difficult because of existing facilities. Distribution power and telephone were placed at 30 inches in a joint-use trench. To avoid damaging distribution power and telephone, CATV placed their COAX cables in the top 18 inches of the easement. Existing copper service drops were also placed at 18 inches. That leaves very little space for new trenching.

In extremely congested areas, municipality permitting, micro-trenching may be in order. Micro-trenching is a method in which fiber and conduit are inserted into a slot-cut trench less than ¾ inches wide and between 9 and 12 inches deep, without damaging or disrupting existing infrastructure.

To avoid other utilities in the easement where possible fiber is placed, use horizontal boring techniques to a depth of 3 or more feet. That takes care of the fiber cable, but the expense of horizontal boring service drops is too expensive. In many instances fiber drops or PVC pipes to the residence are placed at a depth of 6 inches to avoid damaging other utilities but this opens the door to landscaping damage and service disruption.

As an example, in one area that I am aware of, a Telco placed FTTH brownfield construction to over 180,000 other homes in 10 cities. It took the Telco 2 years to install the fiber and place an Optical Network Unit (ONU) in every garage. There was a plethora of damage to existing facilities. When the project was completed the Telco offered The Triple Play over FTTH. Their take rate was less than 5%. The local cable company outperformed them both in cost and content.

Aerial FTTH
Replacing the copper infrastructure with fiber is a slam dunk if the telephone poles are not damaged and the strand is in order. The new fiber can be lashed over the existing copper cables. If the strand is loaded with several copper cables, then the existing cables can be de-lashed and then the fiber can be re-lashed in a continuing process. In many instances, it is economical to place a new strand, place the fiber, and remove the copper cables after the customers are transferred to the new fiber cable.

One problem that needs to be addressed is: Who owns the telephone poles? Access to utility poles has to be granted by the utility pole owner. This may deter investment. In some instances G.fast over existing aerial cables may be the answer.

G.fast is a viable alternative to FTTH in brownfield construction and in multi-dwelling units such as apartment buildings, especially those where it’s difficult to acquire permission to place the fiber into the living space.

Signing off
We love to explore specific, technical issues, so if you have a strange case of trouble — whether funny, interesting, or tough-to-solve — let Vernon May and me know, and we will dive into it. If you don’t want your name and/or company name shared, no problem; we will keep any posts anonymous. Contact me at 831.818.3930 or dmccarty@mccartyinc.com or Vernon May at 254.979.4749 or Vernon@vmaysolutions.com. If you’d like to receive our newsletter, please send an email to scain@mccartyinc.com.

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About Author

Don McCarty is the OSP EXPERT columnist for ISE magazine, discussing the issues around provisioning, testing, and maintaining copper for all services from POTs to IPTV. Don is also president of and the lead trainer for McCarty Products, a technical training and products company training field technicians, cable maintenance, installation repair, and Central Office technicians and managers. For more information, email dmccarty@mccartyinc.com or visit www.mccartyinc.com.

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