U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 4
PUBLICATION DATE: 06/12/1984
Station ID: 8550658 SUPERCEDED DATE: 04/21/2003
Name: RAILROAD BRIDGE, CHRISTINA RIVER
DELAWARE
NOAA Chart: 12311 Latitude: 39° 43.5' N
USGS Quad: WILMINGTON SOUTH Longitude: 75° 33.6' W
To reach the tidal bench marks from the Delaware Memorial Bridge, proceed north
on U.S. Route 13 to Wilmington, past the intersection of U.S. Route 13 and
Interstates 295 and 495 to the first U turn after railroad overpass, at U turn
proceed on U.S. Route 13 south to fork in road, bear right onto dead end street
adjacent to railroad overpass, then proceed to the railroad swing bridge. The
bench marks are located around the bridge and along the dead end street. The
tide gage and staff were located on the railroad bridge fender.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 0658 A 1982
MONUMENTATION: Survey Disk VM#: 2961
AGENCY: PID:
SETTING CLASSIFICATION: Concrete Foundation
The bench mark is set flush in the top of a 5 x 5 concrete pad, located on
railroad bridge superstructure on the NE side of bridge, 6.0 feet (1.8 m) north
from the north rail, and 3.0 feet (0.9 m) east from the base of the NE side of
the bridges superstructure.
BENCH MARK STAMPING: 0658 B 1982
MONUMENTATION: Survey Disk VM#: 2962
AGENCY: PID#: JU2507
SETTING CLASSIFICATION: Concrete Foundation
The bench mark is set flush in the top of a 6 x 6 concrete abutment, located on
the 3rd in river concrete bridge abutment on the NE side of the bridge, 103.0
feet (31.4 m) east of the base of bridge superstructure, and 9.0 feet (2.7 m)
north of the north rail.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 4
PUBLICATION DATE: 06/12/1984
Station ID: 8550658 SUPERCEDED DATE: 04/21/2003
Name: RAILROAD BRIDGE, CHRISTINA RIVER
DELAWARE
NOAA Chart: 12311 Latitude: 39° 43.5' N
USGS Quad: WILMINGTON SOUTH Longitude: 75° 33.6' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 0658 C 1982
MONUMENTATION: Survey Disk VM#: 2963
AGENCY: PID:
SETTING CLASSIFICATION: Concrete Foundation
The bench mark is set flush in the top of a concrete slab, located on the SE
side of the railroad bridge at the shoreline, 110.0 feet (33.5 m) east of Bench
Mark 0658B 1982, 8.0 feet (2.4 m) south from the south rail, at the base of the
eastern end of bridge, and 7.0 feet (2.1 m) from the Pennsylvania Railroad
bridge NOTICE sign.
BENCH MARK STAMPING: 0658 D 1982
MONUMENTATION: Survey Disk VM#: 2964
AGENCY: PID:
SETTING CLASSIFICATION: Concrete Foundation
The bench mark is located on the NE corner of a concrete slab which is a base
for power transmission cable tower, 99.0 feet (30.2 m) SE of steel construction
power lines supports at the east side of the bridge at the shoreline and 89.0
feet (27.1 m) south of south rail on the eastern shore of railroad bridge. The
bench mark is set flush in the top of a 4 x 4 concrete slab, 2.0 feet (0.6 m)
above the ground surface.
BENCH MARK STAMPING: 0658 E 1982
MONUMENTATION: Survey Disk VM#: 2965
AGENCY: PID:
SETTING CLASSIFICATION: Concrete Foundation
The bench mark is set flush in the top of a 2 x 2 concrete slab, 33.0 feet (10.1
m) railroad signal south of signal light which is on north the side of the
rails, 8.0 feet (2.4 m) west of the easternmost box located 7.5 feet (2.3 m)
south of southrail and 6.0 feet (1.8 m) east of the westernmost box.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 4
PUBLICATION DATE: 06/12/1984
Station ID: 8550658 SUPERCEDED DATE: 04/21/2003
Name: RAILROAD BRIDGE, CHRISTINA RIVER
DELAWARE
NOAA Chart: 12311 Latitude: 39° 43.5' N
USGS Quad: WILMINGTON SOUTH Longitude: 75° 33.6' W
T I D A L D A T U M S
Tidal datums at RAILROAD BRIDGE, CHRISTINA RIVER based on:
LENGTH OF SERIES: 60 HIGHS & 60 LOWS
TIME PERIOD: OCTOBER 4 - NOVEMBER 5, 1982
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 (10/10/1982) = 7.47
MEAN HIGHER HIGH WATER MHHW = 5.88
MEAN HIGH WATER MHW = 5.49
MEAN TIDE LEVEL MTL = 2.84
MEAN LOW WATER MLW = 0.19
MEAN LOWER LOW WATER MLLW = 0.00
LOWEST OBSERVED WATER LEVEL (10/17/1982) = -0.84
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In FEET above:
Stamping or Designation MLLW MHW
0658 A 1982 15.87 10.38
0658 B 1982 12.23 6.74
0658 C 1982 14.45 8.96
0658 D 1982 10.66 5.17
0658 E 1982 13.64 8.15
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 4
PUBLICATION DATE: 06/12/1984
Station ID: 8550658 SUPERCEDED DATE: 04/21/2003
Name: RAILROAD BRIDGE, CHRISTINA RIVER
DELAWARE
NOAA Chart: 12311 Latitude: 39° 43.5' N
USGS Quad: WILMINGTON SOUTH Longitude: 75° 33.6' 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.