U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 4
PUBLICATION DATE: 09/01/1982
Station ID: 8545120 SUPERCEDED DATE: 04/21/2003
Name: MARKET STREET BRIDGE, SCHUYLKILL RIVER, PHILADELPH
PENNSYLVANIA
NOAA Chart: 12313 Latitude: 39° 57.3' N
USGS Quad: PHILADELPHIA Longitude: 75° 10.8' W
To reach the tidal bench marks from City Hall in downtown Philadelphia,
Pennsylvania, which is on Market Street, proceed west on Market Street for 8
blocks to the Market Street Bridge over the Schuylkill River. The bench marks
are set in foot of the bridge and along railroad tracks under the east side of
the bridge. The tide gage and staff were located along a bulkhead to the north
of the Market Street Bridge, 74 feet (22.6 m) north of Bench Mark 5120 A 1981.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 5120 A 1981
MONUMENTATION: Survey Disk VM#: 2941
AGENCY: PID:
SETTING CLASSIFICATION: Concrete Foundation
The bench mark is set flush in a 4 x 4 foot concrete slab directly next to the
north side of the bridge abutment on the east side of the Schuylkill River under
the Market Street Bridge at the north end of the support foundation, 35 feet
(10.7 m) NW of a set of railroad tracks under the bridge, and in the SW corner
3-inches (0.1 m) from the NW face of the foundation.
BENCH MARK STAMPING: 5120 B 1981
MONUMENTATION: Survey Disk VM#: 2942
AGENCY: PID:
SETTING CLASSIFICATION: Concrete Foundation
The bench mark is set flush in the base of the Market Street Bridge suport on
the south side of the bridge, and 9 feet (2.7 m) west of the adjacent railroad
tracks, and 2-inches (0.1 m) from the SW corner of the base.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 4
PUBLICATION DATE: 09/01/1982
Station ID: 8545120 SUPERCEDED DATE: 04/21/2003
Name: MARKET STREET BRIDGE, SCHUYLKILL RIVER, PHILADELPH
PENNSYLVANIA
NOAA Chart: 12313 Latitude: 39° 57.3' N
USGS Quad: PHILADELPHIA Longitude: 75° 10.8' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 5120 C 1981
MONUMENTATION: Survey Disk VM#: 2943
AGENCY: PID:
SETTING CLASSIFICATION: Concrete Platform
The bench mark is set flush on a concrete platform in between the Market Street
and Chestnut Street Bridges, 20 feet (6.1 m) east of the easternmost set of
railroad tracks, and 7-inches (0.2 m) from the northernmost corner of a 3.5 foot
(1.1 m) high concrete platform.
BENCH MARK STAMPING: 5120 D 1981
MONUMENTATION: Survey Disk VM#: 2944
AGENCY: PID:
SETTING CLASSIFICATION: Concrete Platform
The bench mark is set flush in a 3.5 foot (1.1 m) high concrete platform in
between Market Street and Chestnut Street Bridges, 30 feet (9.1 m) east of the
easternmost set of railroad tracks under the Market Street Bridge, and 14 feet
(4.3 m) east from the edge of the platform next to the third outward extension
of brickwork on the building next to the railroad tracks.
BENCH MARK STAMPING: 5120 E 1981
MONUMENTATION: Survey Disk VM#: 2945
AGENCY: PID:
SETTING CLASSIFICATION: Concrete Platform
The bench mark is set flush on a concrete platform base of the Chestnut Street
Bridge, 225 feet (68.6 m) south of the Market Street Bridge, 17.5 feet (5.3 m)
NW from the Chestnut Street Bridge support, 3 feet (0.9 m) east of the
easternmost set of railroad tracks, and 5-inches (0.2 m) from the NW corner of a
concrete platform base.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 4
PUBLICATION DATE: 09/01/1982
Station ID: 8545120 SUPERCEDED DATE: 04/21/2003
Name: MARKET STREET BRIDGE, SCHUYLKILL RIVER, PHILADELPH
PENNSYLVANIA
NOAA Chart: 12313 Latitude: 39° 57.3' N
USGS Quad: PHILADELPHIA Longitude: 75° 10.8' W
T I D A L D A T U M S
Tidal datums at MARKET STREET BRIDGE, SCHUYLKILL RIVER, PHILADELPH based on:
LENGTH OF SERIES: 183 HW & 184 LW
TIME PERIOD: MAY 16 - AUGUST 18, 1981
TIDAL EPOCH: 1960-1978
CONTROL TIDE STATION: 8545530 PHILADELPHIA, PA
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in FEET:
HIGHEST OBSERVED WATER LEVEL (06/04/1981) = 7.73
MEAN HIGHER HIGH WATER MHHW = 6.54
MEAN HIGH WATER MHW = 6.10
MEAN TIDE LEVEL MTL = 3.13
MEAN LOW WATER MLW = 0.16
MEAN LOWER LOW WATER MLLW = 0.00
LOWEST OBSERVED WATER LEVEL (06/27/1981) = -0.80
Bench Mark Elevation Information In FEET above:
Stamping or Designation MLLW MHW
5120 A 1981 12.39 6.29
5120 B 1981 11.56 5.46
5120 C 1981 17.03 10.93
5120 D 1981 16.97 10.87
5120 E 1981 12.97 6.87
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 4
PUBLICATION DATE: 09/01/1982
Station ID: 8545120 SUPERCEDED DATE: 04/21/2003
Name: MARKET STREET BRIDGE, SCHUYLKILL RIVER, PHILADELPH
PENNSYLVANIA
NOAA Chart: 12313 Latitude: 39° 57.3' N
USGS Quad: PHILADELPHIA Longitude: 75° 10.8' 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.