===+========+========+=======+======+====+=====+===============+========|
W | | | | UNAVOIDABLE DELAYS |
e | | | AVERAGE TIME |(NOT INCLUDED IN AVERAGE|
i o| | | PER RING. | TIME PER RING). |
g f| | |-------+------+----+-----+---------------+--------|
h |Average | Time | | | | | | |
t i| No. of |mucking,|Shoving| | | | | |
r| cubic | per | and | Erec-| | | | |
o| yards | cubic |mucking| tion |Lost| | | Time |
n|per ring| yard | [Z] | [A] |time|Total| Items |hrs min|
---+--------+--------+-------+------+----+-----+---------------+--------|
{| 48.7 | 0-25 | 20-33 | 4-21|0-12|25-06|First bulkhead | 80-00|
O {| 44.2 | 0-46 | 33-44 | 4-44|1-15|39-43|Second bulkhead| 156-00|
r {| 39.0 | 0-12 | 8-06 | 2-23|0-30|10-59|Grouting rock | 280-00|
d {| 41.6 | 0-10 | 7-10 | 1-59|0-0 | 9-09| sections| |
i {| | | | | | |Blow-outs | 222-00|
n {| 42.6 | 0-10 | 7-23 | 2-35|0-05|10-03|Shield repairs | 326-40|
a {| 13.8 | 0-11 | 2-29 | 2-32|0-20| 5-21|Horz. timbers | 69-30|
r {| 3.6 | 0-06 | 0-40 | 2-39|0-14| 3-33| Total |1,134-10|
y {|--------+--------+-------+------+----+-----+---------------+--------|
{| 17.8 | 0-14 | 4-14 | 2-41|0-16| 7-11|Per ring | 0-53|
---+--------+--------+-------+------+----+-----+---------------+--------|
Hvy| 10.6 | 0-4 | 0-56 | 1-57|0-16| 3-09| | |
---+--------+--------+-------+------+----+-----+---------------+--------|
All| 14.1 | 0-10 | 2-28 | 2-18|0-15| 5-01| | |
===+========+========+=======+======+====+=====+===============+========|
[Z] Including time for jacks.
[A] Including bolting time.
[B] Excavating ahead of shield.
[C] Shoving shield into silt with ... doors open.
The average time taken for each operation at all the working faces is
given in Table 28. The work has been subdivided into the different kinds
of ground encountered.
The progress, as shown by the amount of work done each month by each
shield, is given in Table 29.
TABLE 28.--SHIELD-DRIVEN TUNNEL WORK.--TOTAL NUMBER OF RINGS ERECTED AND
SHIFTS WORKED BY ALL FOUR SHIELDS IN CONTRACTS GY-WEST AND GJ, AND THE
AVERAGE SIZE OF GANG, AMOUNT OF EXCAVATION AND TIME TAKEN PER RING FOR
THE VARIOUS OPERATIONS INVOLVED IN BUILDING TUNNEL IN EACH OF THE
SEVERAL KINDS OF GROUND ENCOUNTERED; ALSO THE EXTENT AND NATURE OF ALL
THE UNAVOIDABLE DELAYS.