====+====+=======+========+=======+=======+=============+========|
| | | |
| | | |
| | | |
| | | |
| | | |
| | | AVE. UNAVOIDABLE |
| | | DELAY PER |
| | AVERAGE TIME PER RING. | WORKING FACE. |
Cu. |Time|------------------------+-------+-------------+--------|
yd. |per |Shoving| | | | | Time |
per |cu. | and | | Lost | | Items |--------|
ring|yd. |mucking|Erecting| time | Total |not included |Ave unit|
----+----+-------+--------+-------+-------| in previous |--------|
Unit|Unit|Hrs Min|Hrs Min |Hrs Min|Hrs Min| figures |Hrs Min |
| | K | L | M | | | |
----+----+-------+--------+-------+-------+-------------+--------|
51 |0-27| 25 15| 3 41 | 0 02| 28 58|1st Bulkhead |136 00 |
45 |0-26| 19 31| 2 55 | 0 11| 22 37| 2d " |147 54 |
| | | | | | | |
39 |0-12| 7 31| 2 24 | 0 20| 10 15|Grouting |246 00 |
| | | | | | | |
43 |0-09| 6 46| 2 24 | 0 09| 9 19|Blow-outs | 91 11 |
| | | | | | | |
42 |0-06| 4 09| 2 51 | 0 10| 7 10|Miscellaneous|230 33 |
| | | | | | | |
43 |0-21| 14 47| 3 41 | 1 34| 20 02|Total |851 38 |
| | | | | | | |
----+----+-------+--------+-------+-------+-------------+--------|
| | | | | | | |
43 |0-18| 11 02| 2 54 | 0 16| 14 12| | |
----+----+-------+--------+-------+-------+-------------+--------|
12 |0-07| 1 20| 2 35 | 0 14| 4 12| | |
----+----+-------+--------+-------+-------+-------------+--------|
12 |0-05| 0 58| 1 44 | 0 10| 2 52| | |
----+----+-------+--------+-------+-------+-------------+--------|
| | | | | | | |
12 |0-06| 1 09| 2 05 | 0 12| 3 26| | |
----+----+-------+--------+-------+-------+-------------+--------|
20 |0-11| 3 33| 2 15 | 0 13| 6 01| | |
----+----+-------+--------+-------+-------+-------------+--------|
Average delay per ring--0 hrs. 44 min.
Average rings built by one shield = 1,146¼.
Average time per ring. 6 hr 01 min
Delays. 44 min
-----------
Total time per ring. 6 hr 45 min
NOTE.--The "unavoidable delays" included in this table do not embrace
the periods during which the work was at complete or partial standstill
due to experiments and observations, shortage of iron due to change of
design, and holidays.
K-Including time for jacks.
L-Including time spent by the whole gang on bolting; in
addition to this there was a small gang which spent its
whole time bolting.
M-Chiefly due to breakdowns of hydraulic lines and
erector.
_Air Pressure._--The air pressure varied from 17 to 37 lb. Behind the
river line it averaged 17 lb. and under the river 26 lb. Behind the
river lines the pressure was generally kept about equal to the water
head at the crown, except where at Weehawken, as previously described,
this was impossible.
In the silt the pressure was much lower than the hydrostatic head at the
crown, but if it became necessary to make an excavation ahead of the
shield, for example at the junction of the shields, the air pressure
required was about equal to the weight of the overlying material,
namely, the water and the silt, as the silt, which weighed from 97 to
106 lb. per cu. ft. and averaged 100 lb. per cu. ft., acted like a
fluid.