Develop an accurate, map-based fiber network inventory and engage ITS team in the construction approval process.
Experience from iFlorida Model Deployment
Before 2007, the FDOT ITS Group had played a reactive role in the process of protecting and repairing their fiber. When a fiber cut did occur, the consequences were sometimes magnified because the ITS Group was not immediately notified so repairs could begin. Most contractors had few interactions with the ITS group, and were uncertain who to contact if a problem occurred. If a fiber cut occurred during off hours, the contractor, uncertain who to contact, might not report the cut immediately. Meanwhile, network monitors would note the loss of connectivity and began contacting FDOT employees by email, pager, and cell phone. FDOT employees would run tests to locate the problem and identify the source of the problem as being damaged fiber in a construction zone. In some cases, ongoing construction activities would have buried the damaged fiber by the time FDOT responded, and FDOT would have to run additional tests to determine the exact location of the cut and re-excavate the damaged fiber before repairs could be made.
In 2007, FDOT began taking a more pro-active stance in addressing the problem of fiber cuts. The goal was to reduce the number of fiber cuts and reduce the impact when a cut was made. Lessons learned on fiber network maintenance are presented below.
- Engage the agency's ITS team in the construction approval process to help ensure the fiber network is included in construction plans. ITS fiber was often not included on construction plans. Until recently, the ITS Group was not integrated into the FDOT construction planning process. In some cases, ITS fiber was not included on construction plans and issues were often not identified until plans were nearly complete. When it was included, it was often first included in the 30 percent plans. At that point, the cost of modifying the plans was higher than if it had been done earlier in the planning process, and some approaches for avoiding damage to ITS fiber were no longer feasible. The ITS Group stated that their goal was to be fully integrated as part of the normal DOT process of identifying, designing, and building projects. FDOT identified several steps it could take to better protect its fiber:
- Large projects pass through FDOT's consultant project management process. FDOT modified procedures for this process so that the ITS Group would be notified early in the planning process and could participate in early planning meetings between FDOT and the contractor. This helped ensure that the construction plans took into account the ITS infrastructure. It also gave FDOT the chance to take steps to reduce the amount of damage to the ITS infrastructure if damage did occur.
- Smaller projects (local area projects and special projects) did not go through the FDOT consultant project management process. To ensure that protection of ITS resources was considered in these projects, FDOT began developing relationships with the various city and county government bodies that managed these projects. An ITS Group staff member began attending weekly project review meetings at these organizations at least once per month. This helped develop relationships between the ITS Group and those managing the local area projects and the local area project contractors.
- Develop an accurate, map-base inventory of fiber network assets. The exact location of the ITS fiber was often not known. Sometimes, the actual deployment and as-built drawings differed too much to be useful guides for whether construction activities would damage the fiber. FDOT also found that using the toning wire to locate the fiber often was not accurate enough to avoid fiber cuts. The FDOT ITS Group began to develop a more accurate inventory of the location of their fiber. This GIS-based inventory would allow FDOT to provide more accurate information about the location of fiber to construction contractors before construction begins.
- Ensure the construction contractor knows who to communicate with in the event of damage to fiber installations. Contractors often were not certain how to contact FDOT to get further information if something in the field caused them to be concerned that they might damage some fiber. Not certain who to contact, contractors would often proceed with construction activities. If a fiber cut did occur, the contractor still might have been uncertain who to contact, and the damage would not be reported until FDOT detected it.
- Consider making fiber visible. In general, FDOT located fiber underground as a means of protecting it from damage. Making fiber difficult to see, however, has made it more prone to damage during construction activities. FDOT noted that contractors typically avoided damaging overhead fiber because it is visible to them. FDOT began repositioning the fiber along some limited access roads from underground to above ground along the fence line during long-term construction projects on limited access roads. FDOT believed that making the fiber part of a visible obstruction (i.e., the fence) helped protect it from inadvertent damage.
- Consider locating fiber near features that construction contractors are likely to avoid. FDOT noted that, with overhead fiber, the presence of nearby power lines made contractors more cautious. FDOT began considering the advantages of laying new fiber near other features that contractors were already prone to avoid, such as underground pipelines.
- Consider relocating the fiber before construction begins. In many cases, FDOT felt it was unrealistic to expect a contractor to avoid cutting fiber during prolonged construction activities. Multiple fiber cuts that might occur would result in costs for repairing the fiber, disruption of ITS services, and lower quality fiber connections (since the splices required to repair fiber reduce the overall quality of the fiber). Because most contractors included in their bid a reserve to pay for damages that may occur, the potential for fiber cuts actually results in increased construction costs for FDOT. FDOT began to consider moving the fiber away from the construction site in order to lower overall costs and better ITS service.
- In one recent intersection reconstruction project (at SR 436 and SR 50), both ITS equipment and fiber were located at the site. FDOT decided that it would be more cost effective to re-route the fiber and move the ITS equipment than to maintain it during the construction. The ITS Group coordinated with the City of Orlando, Seminole County, and Orlando-Orange County Expressway Authority (OOCEA) to make use of nearby dark fiber that these organizations had available, enabling FDOT to reroute fiber around the SR 436/SR 50 intersection. The strong relationship between the FDOT’s ITS Group and these other agencies was key towards achieving this level of cooperation and sharing of resources. This approach was cost-effective because it required deploying only a small amount of new fiber.
- Consider increasing the amount of slack included in fiber deployments. FDOT has begun the practice of including large amounts of excess slack in areas where they expect to later deploy additional field equipment. This allowance can reduce the amount of rework required when the new equipment is deployed. FDOT recently had to rework several miles of infrastructure due to inadequate slack deployed in previous projects.
- Prevent damage to fiber network from mowing activities. Another cause of fiber cuts noted by FDOT was mowing activities. It was common for contractors working on fiber to not bolt down the covers on fiber hubs. If a mower passed over a hub cover that was not bolted down, it could either lift the cover and break it or, if the hub cover was not recessed, hit the cover directly and break it. Once the cover was broken, the suction from the mower could pull the fiber bundle up into the mower blades, cutting the fiber.
Author: Robert Haas (SAC); Mark Carter (SAIC); Eric Perry (SAIC); Jeff Trombly (SAIC); Elisabeth Bedsole (SAIC): Rich Margiotta (Cambridge Systematics)
Published By: United States Department of Transportation Federal Highway Administration 1200 New Jersey Avenue, SE Washington, DC 20590
Source Date: 01/30/2009
EDL Number: 14480URL: http://ntl.bts.gov/lib/31000/31000/31051/14480.htm
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Lesson of the Month for October, 2009 !