U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 5
PUBLICATION DATE: 02/03/1986
Station ID: 8518643 SUPERCEDED DATE: 04/21/2003
Name: RANDALLS ISLAND, HARLEM RIVER
NEW YORK
NOAA Chart: 12339 Latitude: 40° 48.0' N
USGS Quad: CENTRAL PARK Longitude: 73° 55.7' W
To reach the tidal bench marks from the Triboro Bridge take the Downing Stadium
exit ramp, turn left at the first opportunity, proceed west towards the Harlem
River, and turn left into the Police Boat Repair Station just north of the
bridge. The bench marks are located around the Police Boat Repair Station
building and the Triboro Bridge. The tide gage and staff were at the end of the
pier closest to the bridge.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 8643 A 1981
MONUMENTATION: Survey Disk VM#: 2368
AGENCY: PID:
SETTING CLASSIFICATION: Deep Rod
The bench mark is 72 feet (22 m) west of the west face of the Police Boat Repair
building, 60 feet (18 m) south of the north boundary fence of the Police Boat
Repair Station, 37.5 feet (11.4 m) north of the center of the drydock tracks,
20.4 feet (6.2 m) north of the north side of the northernmost pier at the Police
Boat Repair Station, and 8.0 feet (2.4 m) east of the west boundary fence at the
repair station. The bench mark is crimped to the top of a deep rod driven 45
feet (14 m) to refusal on the grounds of the Police Boat Repair Station.
BENCH MARK STAMPING: 8643 B 1981
MONUMENTATION: Survey Disk VM#: 2369
AGENCY: PID:
SETTING CLASSIFICATION: Concrete Foundation
The bench mark is set flush in the concrete garage footing in the north face of
the Police Boat Repair Station, 44 feet (13 m) south of the north boundary fence
of the Police Boat Repair Station, 12.4 feet (3.8 m) east of the west end of the
building, 9.1 feet (2.8 m) east of the west end of the garage door, and 0.5 foot
(0.2 m) south of the north face of the building.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 5
PUBLICATION DATE: 02/03/1986
Station ID: 8518643 SUPERCEDED DATE: 04/21/2003
Name: RANDALLS ISLAND, HARLEM RIVER
NEW YORK
NOAA Chart: 12339 Latitude: 40° 48.0' N
USGS Quad: CENTRAL PARK Longitude: 73° 55.7' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 8643 C 1981
MONUMENTATION: Survey Disk VM#: 2370
AGENCY: PID:
SETTING CLASSIFICATION: Concrete Abutment
The bench mark is set flush in concrete on the northernmost of the two
rectangular Triboro Bridge piers on the east side of the Harlem River, 9 feet (3
m) north of the southeast corner of the pier, 6 feet (2 m) east of the east edge
of the Harlem River, 1 foot (0.3 m) north of the south corner of a protrusion on
the east face of the pier. The bench mark is 5 feet (2 m) above ground level on
the east side of the pier.
BENCH MARK STAMPING: 8643 D 1981
MONUMENTATION: Survey Disk VM#: 2371
AGENCY: PID:
SETTING CLASSIFICATION: Concrete Roof
The bench mark is set flush in the concrete in the roof of a cinder block
pumphouse which is about 8 feet (2 m) square and 5 feet (2 m) high, 140 feet (43
m) east of the Harlem River, 70 feet (21 m) west of the centerline of the access
ramp to the Triboro Bridge, 0.8 foot (0.2 m) east of the west face of the
pumphouse, and 0.5 foot (0.2 m) south of the north face of the pumphouse. The
bench mark is 5.2 feet (1.6 m) above ground level.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 5
PUBLICATION DATE: 02/03/1986
Station ID: 8518643 SUPERCEDED DATE: 04/21/2003
Name: RANDALLS ISLAND, HARLEM RIVER
NEW YORK
NOAA Chart: 12339 Latitude: 40° 48.0' N
USGS Quad: CENTRAL PARK Longitude: 73° 55.7' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 8643 E 1981
MONUMENTATION: Survey Disk VM#: 2372
AGENCY: PID:
SETTING CLASSIFICATION: Concrete Retaining Wall
The bench mark is set flush in the top of the west end of the concrete retaining
wall on the south side of the entrance ramp to the Triboro Bridge, 120 feet (37
m) south of the south edge of the Triboro Bridge, 22 feet (7 m) south of the
south edge of an elevated exit ramp from the Triboro Bridge, 15 feet (5 m) north
of the centerline of the entrance ramp, 0.5 foot (0.2 m) south of the north end
of the retaining wall, and 0.5 foot (0.2 m) east of the west end of the
retaining wall.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 5
PUBLICATION DATE: 02/03/1986
Station ID: 8518643 SUPERCEDED DATE: 04/21/2003
Name: RANDALLS ISLAND, HARLEM RIVER
NEW YORK
NOAA Chart: 12339 Latitude: 40° 48.0' N
USGS Quad: CENTRAL PARK Longitude: 73° 55.7' W
T I D A L D A T U M S
Tidal datums at RANDALLS ISLAND, HARLEM RIVER based on:
LENGTH OF SERIES: 100 HIGHS & 101 LOWS
TIME PERIOD: MAY 1-JUNE 21, 1981
TIDAL EPOCH: 1960-1978
CONTROL TIDE STATION: 8518750 THE BATTERY
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in FEET:
HIGHEST OBSERVED WATER LEVEL (05/03/1981) = 6.95
MEAN HIGHER HIGH WATER MHHW = 5.19
MEAN HIGH WATER MHW = 4.86
MEAN TIDE LEVEL MTL = 2.55
MEAN LOW WATER MLW = 0.24
LOWEST OBSERVED WATER LEVEL (06/02/1981) = -0.98
Bench Mark Elevation Information In FEET above:
Stamping or Designation MLLW MHW
8643 A 1981 9.76 4.90
8643 B 1981 11.65 6.80
8643 C 1981 15.44 10.58
8643 D 1981 22.00 17.14
8643 E 1981 24.35 19.49
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 5
PUBLICATION DATE: 02/03/1986
Station ID: 8518643 SUPERCEDED DATE: 04/21/2003
Name: RANDALLS ISLAND, HARLEM RIVER
NEW YORK
NOAA Chart: 12339 Latitude: 40° 48.0' N
USGS Quad: CENTRAL PARK Longitude: 73° 55.7' W
D E F I N I T I O N S
Mean Sea Level (MSL) is a tidal datum determined over a 19-year National Tidal
Datum Epoch. It pertains to local mean sea level and should not be confused
with the fixed datums of North American Vertical Datum of 1988 (NAVD88).
NAVD88 is a fixed datum derived from a simultaneous, least squares, minimum
constraint adjustment of Canadian/Mexican/United States leveling observations.
Local mean sea level observed at Father Point/Rimouski, Canada was held fixed as
the single initial constraint. NAVD88 replaces NGVD29 as the national
standard geodetic reference for heights. Bench mark elevations relative to
NAVD88 are available from NGS through the World Wide Web at
National Geodetic Survey.
NGVD29 is a fixed datum adopted as a national standard geodetic reference for
heights but is now considered superseded. NGVD29 is sometimes referred to as
Sea Level Datum of 1929 or as Mean Sea Level on some early issues of Geological
Survey Topographic Quads. NGVD29 was originally derived from a general
adjustment of the first-order leveling networks of the U.S. and Canada after
holding mean sea level observed at 26 long term tide stations as fixed.
Numerous local and wide-spread adjustments have been made since establishment in
1929. Bench mark elevations relative to NGVD29 are available from the National
Geodetic Survey (NGS) data base via the World Wide Web at
National Geodetic Survey.
NAVD88 and NGVD29 are fixed geodetic datums whose elevation relationships to
local MSL and other tidal datums may not be consistent from one location to
another.
The Vertical Mark Number (VM#) and PID# shown on the bench mark sheet are unique
identifiers for bench marks in the tidal and geodetic databases, respectively.
Each bench mark in either database has a single, unique VM# and/or PID# assigned.
Where both VM# and PID# are indicated, both tidal and geodetic elevations are
available for the bench mark listed.
The NAVD88 elevation is shown on the Elevations of Tidal Datums Table Referred
to MLLW only when two or more of the bench marks listed have NAVD88 elevations.
The NAVD88 elevation relationship shown in the table is derived from an average
of several bench mark elevations relative to tide station datum. As a result of
this averaging, NAVD88 bench mark elevations computed indirectly from the tidal
datums elevation table may differ slightly from NAVD88 elevations listed for
each bench mark in the NGS database.