Planning the Route
Having decided to use fiber optics and chosen equipment appropriate for the application, it’s time for us to determine exactly where the cable plant and hardware will be located. One thing to remember – every installation will be unique. The actual placement of the cable plant will be determined by the physical locations along the route, local building codes or laws and other individuals involved in the designs. Differences in premises and outside plant installations lead to separate approaches in the planning. Premises and campus installations can be simpler since the physical area involved is smaller and the options are fewer. Start with a good set of architectural drawings and, if possible, contact the architect, contractor and/or building manager. Having access to them means we have someone to ask for information and advice. Hopefully the drawings are available as CAD files so we can have a copy to do the network cabling design in our computer, which makes tweaking and documenting the design much easier.
If the building is still in the design stage, we normally have the opportunity to provide inputs on the needs of the cable plant. We may then have the opportunity to advise on the location of equipment rooms, routing of cable trays and conduits, availability of adequate conditioned power and separate data grounds, sufficient air-conditioning and other needs of the network. For pre-existing buildings, detailed architectural drawings will provide us with the ability to route cabling and network equipment around the obstacles invariably in our way.
Outside plant (OSP) cabling installations, however, may have differing scenes depending on the routes of the cable. The route may cross long lengths of open fields, run along paved rural or urban roads, cross roads, ravines, rivers or lakes, or, more likely, some combination of all of these. It could require buried cables, aerial cables or underwater cables. Cable may be in conduit, inner duct or direct buried. Aerial cables may be self-supporting or lashed to a messenger. Longer runs often include crossing water, so the cable may be underwater or be lashed across a bridge with other cables.
Visiting the site or route where the network will be installed need to be carried out at the earliest point of time. Outside plant routes need to be driven or walked every foot of the way to determine the best options for cable placement, obstacles to avoid or overcome, and to determine what local entities may have input into the routing. Often cities or other governments will know of available conduits or rules on using utility poles that can save design time and effort.
For installations inside current buildings, we should inspect every area to be absolutely certain we know what the building really looks like and then mark-up drawings to reflect reality, especially all obstacles to running cabling and hardware and walls requiring fire stopping that are not on the current drawings. Wherever permits, appropriate pictures should be taken. For buildings under construction, a site visit is still a good idea, just to get a feeling of what the final structure will be like and to get to know the construction managers you will be working with. They may be the best source of information on who the local authorities are who will be inspecting your work and what their likely expectations.
With all those options on OSP installations, where do we start? With a good map. Not just a road map or a topographical map, but satellite images overlaid on roads will be an advantage e.g. like “Google Maps” can provide. Creating a route map is the first step, noting other utilities along the route on that map, and checking with groups that document the current utilities to prevent contractors from damaging currently installed pipes and cables.
Once we have marked up maps, the real “fun” begins: finding out whose permission we need to run our cabling. OSP installations are subjected to approval by local, state and federal authorities who will influence heavily on our project design. Some cities, for example, ban aerial cables. Some have already buried conduit which we can use for specific routes. Since many municipalities have installed city-owned fiber networks, they may have fiber to be rented, rather than going through the hassle of installing our own. Unless we are doing work for a utility that has someone who already has the contacts and hopefully easements needed, we may get to know a whole new set of people who have control over our activities. And we have to plan for adequate time to get approval from everyone who is involved.
Call Before You Dig
Digging safely is vitally important. The risk is not just interrupting communications, but the life-threatening risk of digging up high voltage or gas lines. Some obstacles may be found during site visits, where signs like these are visible. There are several services that maintain databases of the location of underground services that must be contacted before any digging occurs, but mapping these should be done during the design phase and double-checked before digging to ensure having the latest data.
If all this sounds vague, it is. Every project is different and requires some careful analysis of the conditions before even beginning to choose fiber optic components and plan the actual installation. Experience and knowledge is the best teacher.
2. Open trenching (Grass Verge Trenching Works)
The typical operating crew for trenching (GV) Works consists of five people to carry out the trenching works. The five person crew consists of one individual to operate Backhoe, one to monitor under utilities during trenching, two to join and lay ducts and one to take charge safety on site. The usual operation consists of first excavating pilot holes/pits (normally to depth of 1.2m) at both end of the proposed route. The purpose of this pilot holes/pits are to locate and confirmed the location and confirmed the location and depth of underground utilities.
Once these pilot holes/pits were dug, verification of existing underground utilities and their depth will be carried out. Additional pilot hole will be dug at the gas pipe crossing area to confirm the gas pipes depth and actual alignment with the assistance by competence Gas Malaysia personnel. Subsequently, trenching works will be carried out by backhoe at depth of 0.6m for Gas Pipe Crossing. After the excavation, 2 way PN10/PVC duct will be laid and backfilled with 200mm sand before laying of warning tape and top up with soil.
3. HDD (Horizontal Directional Drilling Works)
The typical operating crew for HDD Works consists of five people to run the HDD system plus additional help to handle ducting/pipes and provide the necessary starting and exit pits for termination on some jobs. The five person crew consists of one individual to do locating, one to control and operate the advancing and steering of the HDD machine, two to assist add and remove section of drill pipe and one to take charge safety on site. After the existing utilities have been located and the boring path had been laid out, the usual operation consists of first excavating pilot holes/pits at both the entry and exit points. The purpose of this pilot holes/pits are to locate and confirmed the location and depth of underground utilities (if any prior to any HDD works).
Once these pilot holes/pits were dug, the HDD machine is brought near to the entry point. The HDD machine is set up 4m to 5m behind the entry pit. The tool and the first 3m section of drill rod are put on the HDD machine, which is angle at about 15 degree to the ground. The guided initial boring process begins by drilling into the entry pit at 15 degree angle. After the first 3m section of drill rod is advanced into the ground, the second rod is added. The process continues with the steering controlled so that the boring tool will enter the entry pit level at proper depth. The guided boring procedure will then continue toward the exit pit guided by the Sonde and Relocator.
The Relocator Operator shall continue monitor the progress and position the drilling head, transmitting steering commands back to the steering operator at the HDD machine via walkie-talkie. The steering operator controls the tool through orientation of the jets and by applying thrust force on the end of the drill string. Continuous rotation shall allow the drill rods and drill head to advance to the exit it at a specific depth and profile.
Once the drill rods and drill head had advance to the exit point, the drill head which housed the Sonde/transmitter is removed and a back reamer is attached to the drill rod. The initial bore size is 50mm the back reamers allow to bore hole to be expanded up to 700mm. Attached to the end of the reamer is a swivel joint and a gripping mechanism for pulling the utility ducting or pipes. The back reaming process is merely the reverse of the drilling process with no need for guidance. The HDD machines withdraw the drill rods at the same time as the utility ducting/pipes are being installed.
4. Micro Trenching
A micro trencher is a "small rock wheel" specially designed for work in urban area. It is fitted with a cutting wheel that cuts a micro trench with smaller dimensions than can be achieved with conventional trench digging equipment. Micro trench widths range from about 30 to 130 mm (1.2 to 5.1 in) with a depth of 500 mm (20 in) or less. These machines are sometimes radio-controlled.
With a micro trencher, the structure of the road is maintained and there is no associated damage to the road. Owing to the reduced trench size, the volume of waste material excavated is also reduced. Micro trenchers are used to minimize traffic or pedestrian disturbance during network laying. They may also be used to install FTTx connections. A micro trencher can work on side walks or in narrow streets of cities, and can cut harder ground than a chain trencher, including cutting through solid stone. They are also used to cut pavement for road maintenance and to gain access to utilities under roads.
A portable trencher machine in operation. Landscapers and lawn care specialist may use a portable trencher to install landscape edging and irrigation lines. These machines are lightweight (around 200 pounds) and are easily manoeuvrable compared to other types of trenchers. The cutting implement may be a chain or a blade similar to a rotary lawn mower blade oriented so that it rotates in a vertical plane.