Transactions of the American Society of Civil Engineers

Table 1

Shifts: Number of shifts covered by observations.

Hours: Average number of hours worked per shift.

D/Hr: Average depth drilled per hour per drill

D/Yd: Average depth drilled per yard.

Hack.: Hackensack

Whk.: Weehawken

Cs: Central Shaft

Method.	Date.	Shifts	Place.		Hours	D/Hr	D/Yd
No. 1— 4-drill	Aug. ’06	44	Hack.,	N.	5.69	2.78	10.1
	Sept. ’06	38	″	N.	5.80	3.77	11.1
	Aug. ’06	43	″	S.	5.60	2.89	9.1
	Sept. ’06	36	″	S.	6.18	2.65	8.7
	Jan. ’07	16	CS E.	N.	5.99	2.99	8.2
	Jan. ’07	20	″	S.	6.05	2.9	7.1
	Apr. ’07	48	CS W.	N.	4.92	3.3	6.7
	Apr. ’07	48	″	S.	5.00	3.2	7.7
Nos. 2 and 3— 5-drill	Dec. ’06	54	Whk.,	N.	4.95	2.16	4.52
	Dec. ’06	54	″	S.	5.23	2.14	4.54
	Dec. ’06	52	Hack.,	N.	5.03	2.2	5.77
	Dec. ’06	54	″	S.	5.90	1.82	5.67
No. 4— 7-drill	June ’07	56	Whk.,	N.	4.77	2.55	4.23
	June ’07	58	″	S.	4.82	2.26	3.88
8-drill	May ’07	60	Hack.,	N.	4.67	2.44	5.00
	May ’07	60	″	S.	4.54	2.57	4.80