Part 4
+---------+--------+--------+-----+-----+------+------+-------+ | Drilling and Firing Data for | | Each Sub-division of Section | |---------+--------+--------+-----+-----+------+------+-------| | Sub | Volume | No. of | No. | No. |Total |Linear| Total | |divisions|of each |sets of | of | of | lbs. | feet |length | | | sub- | holes |holes|times| of | of |drilled| | |division| | in |fired|powder|tunnel| | | |paid for| | set | | per |broken| | | | | | | | hole | | | | | | | | |fired | | | |---------+--------+--------+-----+-----+------+------+-------| | _a_ | _b_ | _c_ | _d_ | _e_ | _f_ | _g_ | _h_ | |---------+--------+--------+-----+-----+------+------+-------| | _A_ | 17.775 | {[G] 1 | 6 | 3 | 4.50 | | | | | | {[H] 1 | 9 | 1 | 1.50 | | | | | | {[I] 1 | 6 | 1 | 1.00 | | | | | | {[J] 1 | 6 | 1 | 0.75 | 6.0 | 195 | | | | | | | | | | |---------+--------+--------+-----+-----+------+------+-------| | _A'_ | 1.00 | 2 | 3-4 | 1 | 0.25 | 5.0 | 21 | |---------+--------+--------+-----+-----+------+------+-------| | _B_ | 5.925 | {[G] 2 | 3-4 | 1 | 1.00 | 4.0 | 35 | |---------+--------+--------+-----+-----+------+------+-------| | _C_ | | {[K] 1 | 3 | 2 | 1.125| | | | | 33.33 | 4 | 7 | 1 | 1.125| 5.0 | 186 | |---------+--------+--------+-----+-----+------+------+-------| | _D_ | 6.665 | 2 | 5-6 | 1 | 0.75 | 3.0 | 33 | |---------+--------+--------+-----+-----+------+------+-------| | | | | | | | | |=========+========+========+=====+=====+======+======+=======| | _E_ | 50.00 | | 5 | 1 | 1.50 | 5.0 | 405 | |---------+--------+--------+-----+-----+------+------+-------| | _F_ | 88.88 |{ 10.5| 4 | 2 | 1.50 | | | | | |{[L] 5.0| 4 | 1 | 1.50 | 4.0 | 682 | |---------+--------+--------+-----+-----+------+------+-------| | _G_ | 22.22 | 5.5| 4 | 2 | 1.00 | 5.0 | 132 | |---------+--------+--------+-----+-----+------+------+-------| | | | | | | | | |=========+========+========+=====+=====+======+======+=======| | _H_ | 9.77 |{ 5 | 3 | 1 | 0.50 | | | | | |{ 4 | 6 | 1 | 0.50 | 6.0 | 156 | |---------+--------+--------+-----+-----+------+------+-------| | _I_ | 26.66 | 8 | 5 | 1 | 1.00 | 6.0 | 252 | |---------+--------+--------+-----+-----+------+------+-------| | | | | | | | | | | |========+=====+=====+======+======+=======| | | | | | | | | | | | | | | |========+=====+=====+======+======+=======| | | | | +---------+--------+--------+-----+-----+------+------+-------+
+---------+------+-------+------+------+---------+-------+------+ | Drilling and Firing Data for | | Total Sections | |---------+------+-------+------+------+---------+-------+------| | Sub |Total |Length | Cu. | Cu. | Total | Total | Total| |divisions|length|drilled| yds. | yds. | lbs. of |lbs. of| lbs. | | | of | per | per | per | powder | powder| of | | |simi- |linear |linear|linear| per | per |powder| | |lar |foot of| foot | foot | linear | foot | per | | |head- |tunnel | of | of | foot of |drilled|cubic | | |ings | |tunnel|tunnel| tunnel | | yard | |---------+------+-------+------+------+---------+-------+------| | _a_ | _i_ | _j_ | _k_ | _l_ | _m_ | _n_ | _o_ | |---------+------+-------+------+------+---------+-------+------| | _A_ | |Sigma | | | | | | | | | c + d |b + i | j |c + d + f| m | m | | | | ----- |------| --- | ----- | --- | --- | | | | g | g | k | g | j | k | | | 2 | 65.00 | 5.925|10.97 | 17.00 | 0.261 |2.848 | |---------+------+-------+------+------+---------+-------+------| | _A'_ | 2 | 8.40 | 0.400|21.00 | 0.70 | 0.166 |1.750 | |---------+------+-------+------+------+---------+-------+------| | _B_ | 2 | 17.50 | 2.962| 5.90 | 3.50 | 0.200 |1.181 | |---------+------+-------+------+------+---------+-------+------| | _C_ | | | | | | | | | | 1 | 37.20 | 6.666| 5.58 | 6.975 | 0.187 |1.046 | |---------+------+-------+------+------+---------+-------+------| | _D_ | 2 | 22.00 | 4.444| 4.95 | 5.500 | 0.250 |1.237 | |---------+------+-------+------+------+---------+-------+------| |Total for| |150.10 |20.397| 7.81 | 33.675 | 0.227 |1.778 | | Heading | | | | | | | | |=========+======+=======+======+======+=========+=======+======| | _E_ | 1 | 81.00 |10.000| 8.10 | 13.500 | 0.167 |1.350 | |---------+------+-------+------+------+---------+-------+------| | _F_ | | | | | | | | | | 1 |170.50 |22.222| 7.67 | 23.230 | 0.136 |1.046 | |---------+------+-------+------+------+---------+-------+------| | _G_ | 1 | 26.40 | 4.444| 5.94 | 4.400 | 0.166 |0.990 | |---------+------+-------+------+------+---------+-------+------| |Total for| |277.90 |36.666| 7.56 | 41.150 | 0.150 |1.133 | | Bench | | | | | | | | |=========+======+=======+======+======+=========+=======+======| | _H_ | | | | | | | | | | 1 | 26.00 | 1.628|15.96 | 3.250 | 0.125 |1.995 | |---------+------+-------+------+------+---------+-------+------| | _I_ | 2 | 84.00 | 4.444|18.90 | 13.333 | 0.158 |3.000 | |---------+------+-------+------+------+---------+-------+------| |Total of | |110.00 | 6.072|18.10 | 16.583 | 0.151 |2.731 | | Trench | | | | | | | | |=========+======+=======+======+======+=========+=======+======| |Total for| |548.00 |63.135| 8.95 | 91.408 | 0.172 |1.446 | | Whole | | | | | | | | |Section | | | | | | | | |=========+======+=======+======+======+=========+=======+======| |Powder taken at 0.5 lb. per stick | +---------+------+-------+------+------+---------+-------+------+
[G] 6 Cut Holes-8 feet (Black circle)
[H] 9 First Side Rd. and Bottom-7 feet (Circle with dot in it)
[I] 6 Back Round-7 feet (Circle with line in it)
[J] 6 Top Back Round-7 feet (Circle with x in it)
[K] A' 7 Holes-3 feet (Open circle)
[L] line holes (Plus sign)
TABLE 7.--Analysis of Drilling Time on Section Gy-East.
+========+======+========+=====+=====+=======+========+========+=======+ | | | | AVERAGE TIME TAKEN: | |Position|Nature| No. of |-----+-----+-------+--------+--------+-------| | in | of | Drill | | | | | | | |Section.|Rock. | Shifts |Set- |Dril-|Neces- |Unneces-| Taking |Loading| | | |observed|ting |ling.| sary | sary | down | and | | | | for | up. | |delays.|delays. |machine.|firing.| | | |average.| | | | | | | |--------+------+--------+-----+-----+-------+--------+--------+-------| | | | |h. m.|h. m.| h. m. | h. m. | h. m. | h. m. | | | | |-----+-----+-------+--------+--------+-------| |Heading |Quartz| 8 |0:38 |4:52 | 1:40 | | 0:05 | 0:04 | | | | | | | | | | | |Heading | Hard | 1 |0:15 |8:00 | 1:45 | | | | | | mica | | | | | | | | | |schist| | | | | | | | | | | | | | | | | | | Bench |Quartz| 23 |1:23 |5:57 | 2:23 | 0:05 | 0:05 | 0:07 | | | | | | | | | | | | Bench |Medium| 16 |1:10 |6:08 | 1:50 | 0:12 | 0:07 | 0:07 | | | mica | | | | | | | | | |schist| | | | | | | | | | | | | | | | | | | Center |Medium| 10 |0:58 |5:53 | 1:33 | 0:06 | 0:12 | 0:30 | | trench | mica | | | | | | | | | |schist| | | | | | | | | | | | | | | | | | | Center | Soft | 9 |1:10 |6:40 | 1:17 | 0:10 | 0:20 | 0:23 | | trench | mica | | | | | | | | | |schist| | | | | | | | |--------+------+--------+-----+-----+-------+--------+--------+-------| |General | | 67 |1:08 |5:58 | 1:53 | 0:07 | 0:09 | 0:12 | |average | | | | | | | | | |--------+------+--------+-----+-----+-------+--------+--------+-------| | Per- | | |11.3%|59.7%| 18.9% | 1.1% | 1.5% | 2% | |centage | | | | | | | | | +========+======+========+=====+=====+=======+========+========+=======+
+========+======+=========+========+======+======+========+ | | | AVERAGE TIME TAKEN: | FEET DRILLED. | |Position|Nature|---------+--------+------+------+--------| | in | of | | | | | | |Section.|Rock. | Total |Mucking.|Total.| Per | Per | | | |drilling.| | |shift.|working | | | | | | | | hour. | | | | | | | | | |--------+------+---------+--------+------+------+--------| | | | h. m. | h. m. |h. m. | | | | | |---------+--------+------+------+--------| |Heading |Quartz| 7:19 | 2:41 |10:00 | 22.0 | 2.86 | | | | | | | | | |Heading | Hard | 10:00 | |10:00 | 42.0 | 4.20 | | | mica | | | | | | | |schist| | | | | | | | | | | | | | | Bench |Quartz| 10:00 | |10:00 | 25.9 | 2.59 | | | | | | | | | | Bench |Medium| 9:34 | 0:26 |10:00 | 22.22| 2.32 | | | mica | | | | | | | |schist| | | | | | | | | | | | | | | Center |Medium| 9:12 | 0:48 |10:00 | 22.0 | 2.39 | | trench | mica | | | | | | | |schist| | | | | | | | | | | | | | | Center | Soft | 10:00 | |10:00 | 26.44| 2.64 | | trench | mica | | | | | | | |schist| | | | | | |--------+------+---------+--------+------+------+--------| |General | | 9:27 | 0:33 |10:00 | 24.1 | 2.54 | |average | | | | | | | |--------+------+---------+--------+------+------+--------| | Per- | | 94.5% | 5.5% | 100% | | | |centage | | | | | | | +========+======+=========+========+======+======+========+
TABLE 8.--ANALYZED COST OF DRILLING.
+=============+===========================+===========================+ | | COST PER FOOT OF HOLE | COST PER DRILL SHIFT | |Item of Cost.| DRILLED. | | | +-------+-----+-----+-------+-----+------+------+-------+ | | 15 ft | 9 ft|24 ft|Average|15 ft|19 ft |24 ft |Average| | | 4 in | 6 in| 6 in| | 4 in| 6 in | 6 in | | |-------------+-------+-----+-----+-------+-----+------+------+-------+ |Drilling | $0.25 |$0.28|$0.31| $0.28 |$6.95| $7.75| $7.60| $7.45 | |labor | | | | | | | | | | | | | | | | | | | |Sharpening | 0.02 | 0.02| 0.01| 0.016| 0.58| 0.42| 0.34| 0.43 | | | | | | | | | | | |Drill steel | 0.007|0.007|0.006| 0.007| 0.19| 0.20| 0.15| 0.19 | |(5 in. per | | | | | | | | | |drill shift) | | | | | | | | | | | | | | | | | | | |Drill repairs| 0.02 | 0.02| 0.02| 0.02 | 0.61| 0.59| 0.42| 0.54 | | | | | | | | | | | |High-pressure|[M]0.05| 0.04| 0.07| 0.07 | 1.39| 1.86| 1.67| 1.82 | |air | | | | | | | | | |-------------+-------+-----+-----+-------+-----+------+------+-------+ |Totals | $0.35 |$0.38|$0.41| $0.385|$9.67|$10.82|$10.18|$10.43 | +=============+=======+=====+=====+=======+=====+======+======+=======+
[M] This is an estimated figure, ascertained by taking a proportion of the whole charge for plant running.
_General Methods._--Whenever any considerable support was needed for the ground, segmental timbering was used. In most cases, this was supported by wall-plates at the springing line, and was set with an allowance for settlement, so that it would be clear of the work when the masonry lining was put in. As the twin-tunnel section involved the excavation of the North and South Tunnels at the same time, the cross-section of the upper part of the excavation consisted of two quadrants rising from the springing line and connected at the top by a horizontal piece from 19 to 28 ft. in length. This made a rather flat arch to support by timbering.
The timber for the segmental work was 12 by 12-in. yellow pine. In light ground the bents were spaced at 5-ft. centers, in heavy ground 2-ft. 6-in. centers.
When the soft ground in the roof was struck, posts had to be used in the heading to support the caps. When the bench was removed, the posts were replaced by others down to the bottom of the excavation. These long posts were a great hindrance to all the work, and each replacement of short posts by long ones meant a settlement of the caps; consequently, it was decided to use in the section east of the cut-and-cover, where all the ground was heavy, a temporary inner bent of segmental timber, within and reinforcing the permanent bent, and resting on separate wall-plates. This is shown by Fig. 6. These temporary bents were inside the work, and were removed as the arch was built. However, the caps settled considerably in some cases, so that it was not possible to do away with posting entirely.
In heavy ground the caps were set about 1 ft. above the neat line of the crown of the brick arch, in some cases they were set only 6 in. above, but the settlement was often more than this, causing great trouble in cutting out the encroaching timber when the arch had to be built.
In the tunnels east of the cut-and-cover portion, wall-plate headings were driven (shown by areas marked _A_ on Fig. 5), and, when a length of wall-plate had been set, the full-width heading was advanced a foot or two at a time, the timber segmental bents being set up as soon as possible; lagging was then driven over the cap into the soft ground. Fig. 6 shows the double set of segmental bents adopted in the 15-ft. 4-in. twin tunnels east of the cut-and-cover section.
When the soft ground came down so low as to interfere with the excavation of the wall-plate headings, a small heading was driven into the soft ground on the line of the ends of the caps, and lagging was driven down from this to the wall-plate heading, as illustrated in Fig. 4.
In the 19-ft. 6-in. tunnels the wall-plate for the inner bent was supported by a side-bench, termed the "Raker" bench. This was left in position until the rest of the bench and the middle subgrade conduit trench had been excavated; it was then possible to support the caps by two rows of posts from subgrade level, take out the inner bents, and excavate the raker bench.
The 24-ft. 6-in. twin tunnels, which are at the extreme eastern end of this section, adjoining the open-cut work of the Terminal Station, and under Tenth Avenue, were driven from the Terminal Station-West, and the timbering had to be made very secure on account of the pipes and sewers in the street above. Detailed records were kept of the amount of timber used and the cost of labor and material expended in timbering. These records cover the same portion of tunnel as that for which the detailed records of drilling costs, previously referred to, were kept. These records are shown in Tables 9 and 10. It will be noted that the timber used in blocking, that is, filling up voids outside the main timbering, amounted to more than two-thirds of the total timber, and that the cost of labor in erecting the timbering exceeds the prime cost of the timber by about one-third. The following distinction is made between permanent and temporary timbering: The permanent timbering is that which is concreted in when the masonry is built; the temporary consists of the lower bents and posts, which have to be removed when the masonry is built.
_Force Employed in Excavation._--A typical day's working force for drilling, blasting, mucking, and timbering is shown in Table 11.
Where there was any large quantity of soft ground in the roof, the timber gang was much larger than shown in Table 11, and was helped by the mucking gang. The drillers did most of the mucking out of the heading before setting up the drills.
_Excavation of Weehawken Rock Tunnels._--This subject may be dismissed in a few words, as very few features of interest were called into play. The rock was of good quality, being the sandstone typical of this part of the country. Little or no timbering was needed, there were no buildings above the tunnel to be taken care of, and large charges of powder could be used.
TABLE 9.--SUPPLEMENTARY ANALYSIS OF TIMBERING, ROCK TUNNEL EXCAVATION UNDER 32D STREET, EAST OF CUT-AND-COVER SECTION. ANALYZED COST OF TIMBERING, PER FOOT RUN AND PER BENT.