cable of special design and manufacture. Accordingly, the network of
trenches requested was complex, (requiring approximately 19 drawings to
depict), and the shielding requirements imposed necessitated a considerable amount of engineering consideration.
The first shielding problem, that of affording adequate protection
to the coaxial cables running between Eberiru and Aomon, called for an
evaluation of various suggested schemes including the laying of steel or
rubber conduit in a trench in the floor of the channel between these
islands. After investigation at the site by representatives of the H & N
Engineering Division, it was recommended that the most direct solution to
the problem was the provision of an earth fill causeway in which a wood
frame conduit could be provided for the coaxial cable,
Such a causeway
would have the additional advantage of serving as a direct above-water
roadway between the islands, to facilitate both scientific and construc-
tion operations,
This recommendation was approved, designs for the
causeway were executed, and construction accomplished.
Additional shielding requirements involved the placement of coral
terms over the buried rigid and semi-flexible coaxial lines.
The heights
of these berms varied from more than thirteen feet to five feet, decreasing with distance from zero.
As indicative of the magnitude of the problems involved in connection
with coaxial cable, it will be seen from Table 5.18-3 that a total of more
than 360,000 feet of rigid and semi-flexible coaxial cable and more than
2,000,000 feet of flexible coaxial cable was installed.
tained as many as fifty of these cables.
Some trenches con-
TABLE 5.18-3 COAXIAL CABLE
Runit
Rigid*
Quantity in Lineal Feet
Aomon
Engebi
Engebi (E+)
Total
Estimated
Installed
13,300
13,530
106,200
115,870
58,000
60,600
18,000
41 ,903
195,500
231 ,930
Estimated
Installed
15,000
19,000
22,000
35,560
64,000
59,700
28 ,000
16,450
129 ,000
130,710
Estimated
Installed
1,104,500
1,136,500
180,300
166,300
751,200
757,600
7,800
4,391
2,043,800
2,064,791
Estimated
9,000
Semi-Flexible**
Flexible###
Other*####
Installed
Site Total
Estimated
Installed
8,755
24,400
37 ,400
9,100
16,100
71 ,600
1,141 , 800
1,177,785
345,900
342,130
882,100
887,400
69 ,900
65,721
2,439,700
2,476,036
9,500
2,977
45,632
* Rigid cable, 1-5/8 inch and 3-1/8 inch diameter
** Semi-Flexible, 7/8 inch diameter
*"* Flexible, RGL8U, RG 8U, and RG 360
eHee Other, 2/c #12, 2/c #4, Teleseal, and 7-Quad
9-255