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230 Chapter 9

increases in associated costs have made it an even greater invest-
ment. First, the average price for deploying new cable is estimated to
be $70,000 to $100,000 per mile, and this can be even higher in
densely populated areas. This does not include expenses for support
systems and electronics.Think of the cost of trying to excavate down-
town Manhattan to lay new fibers in the streets. One must look at
the reasonableness of such a maneuver before just considering the
overall costs. The rights of way are getting congested, so every time
a new dig begins, every other cable in the ground is placed at risk of
backhoe fade (cable cuts). Many times the same vendor who laid the
cables cuts the cables when digging anew for another carrier. The
impact of downtime and disruptions is significantly higher than the
cost of splicing (fixing) the cables.
DWDM therefore has been accepted as a cost-effective alternative
when insufficient fiber is in place to meet requirements. Many carri-
ers pulled sufficient fiber for their primary head-end interconnect
routes. As additional hubs were added to the primary ring, certain
segments may contain insufficient fiber, thus placing the carrier at
odds of what to do.
As a simple cost comparison, Scientific-Atlanta created a model to
estimate the cost of DWDM versus the cost of fiber. The model uses
a regional fiber network with a single head end and up to five off-
shoots. Each of the hubs was spaced 30 miles apart. In this model, six
fibers were used in the head-end-to-hub interconnect. Using DWDM,
16 video channels would be delivered over each OC-48, making the
ring capable of transporting either 96 uncompressed analog video
channels or 16 QAM IF digital channels and 80 uncompressed ana-
log video channels—all over a single fiber.
Figure 9-11 compares the cost of using DWDM in this application
with the direct cost of fiber cable. The DWDM estimated cost
includes 1,550-nm OC-48 lasers, a DWDM multiplexer, and a
DWDM demultiplexer. For fiber cable, only the estimated cost of the
cable and splicing is considered. Construction costs are not included.
As expected, the model shows that the estimated cost of DWDM is
favorable to the cost of the alternative option of constructing new
fiber routes. What was not anticipated is the favorable degree of the
DWDM interconnection. The DWDM approach for the model is
expected to reach cost parity with the cost of dedicated fiber for a sin-