U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 5
Station ID: 8724255 PUBLICATION DATE: 03/09/2004
Name: RAMROD KEY
FL
NOAA Chart: 11445 Latitude: 24° 39.6' N ( 24.66000)
USGS Quad: SUMMERLAND KEY Longitude: 81° 25.4' W ( -81.42330)
To reach the tidal bench marks from the post office in Summerland Key, proceed
east on U.S. Highway 1 for 2.3 km (1.4 mi) to the east end of the new bridge
over Niles Channel. The bench marks are located on the new bridge, the old
bridge, and on Ramrod Key. The tide gage and staff were located just south of
the east end of the old bridge.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: NO 1 1937
DESIGNATION: 872 4255 TIDAL 1
MONUMENTATION: Bench Mark disk VM#: 6860
AGENCY: US Coast and Geodetic Survey
(USC&GS) IDB PID#: AA0190
SETTING CLASSIFICATION: Concrete wing wall OPUS PID:
LATITUDE: 24° 39.6' N ( 24.66000) LONGITUDE: 81° 25.4' W ( -81.42330)
The primary bench mark is a disk set in the top of the south concrete wing wall
at the east end of the Niles Channel Viaduct, 21 m (68 ft) south of the
centerline of the highway, 15.61 m (51.2 ft) SE of bench mark NO 2 1937, and 3 m
(10 ft) below highway level.
BENCH MARK STAMPING: NO 2 1937
DESIGNATION: 872 4255 TIDAL 2
MONUMENTATION: Tidal Station disk VM#: 6861
AGENCY: US Coast and Geodetic Survey
(USC&GS) IDB PID#: AA0191
SETTING CLASSIFICATION: Concrete wing wall OPUS PID:
LATITUDE: 24° 39.6' N ( 24.66000) LONGITUDE: 81° 25.4' W ( -81.42330)
The bench mark is a disk set in the top of the south concrete wing wall at the
east end of the Niles Channel Viaduct, 6.86 m (22.5 ft) south of the centerline
of the highway, and 1 m (3 ft) below highway level.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 5
Station ID: 8724255 PUBLICATION DATE: 03/09/2004
Name: RAMROD KEY
FL
NOAA Chart: 11445 Latitude: 24° 39.6' N ( 24.66000)
USGS Quad: SUMMERLAND KEY Longitude: 81° 25.4' W ( -81.42330)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: R 272 1966
DESIGNATION: R 272
MONUMENTATION: Bench Mark disk VM#: 6862
AGENCY: US Coast and Geodetic Survey
(USC&GS) IDB PID#: AA0196
SETTING CLASSIFICATION: Bedrock OPUS PID:
LATITUDE: 24° 39.7' N ( 24.66170) LONGITUDE: 81° 25.9' W ( -81.43170)
The bench mark is a disk set in the top of a large area of exposed bedrock
located at the intersection of Mako Avenue and the old U.S. Highway 1, 111 m
(365 ft) north of and across the old highway from the centerline of U.S. Highway
1, 12 m (40 ft) east of the centerline of Mako Avenue, 8 m (25 ft) north of the
centerline of the old highway, 7.41 m (24.3 ft) ESE of a road sign, and 1 m (4
ft) below U.S. Highway 1 level.
BENCH MARK STAMPING: 4255 F 1982
DESIGNATION: 872 4255 F TIDAL
MONUMENTATION: Tidal Station disk VM#: 6863
AGENCY: National Ocean Survey (NOS) IDB PID#: AA1012
SETTING CLASSIFICATION: Concrete guardrail OPUS PID:
LATITUDE: 24° 39.6' N ( 24.66000) LONGITUDE: 81° 25.4' W ( -81.42330)
The bench mark is a disk set flush in the top of the concrete guardrail of the
new U.S. Highway 1 bridge, 5.97 m (19.6 ft) south of the centerline of U.S.
Highway 1 bridge, 1.86 m (6.1 ft) west of the SE end of the concrete guardrail,
and 1 m (3 ft) above the road.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 5
Station ID: 8724255 PUBLICATION DATE: 03/09/2004
Name: RAMROD KEY
FL
NOAA Chart: 11445 Latitude: 24° 39.6' N ( 24.66000)
USGS Quad: SUMMERLAND KEY Longitude: 81° 25.4' W ( -81.42330)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 4255 G 1982
DESIGNATION: 872 4255 G TIDAL
MONUMENTATION: Tidal Station disk VM#: 6864
AGENCY: National Ocean Survey (NOS) IDB PID#: AA1013
SETTING CLASSIFICATION: Concrete guardrail OPUS PID:
LATITUDE: 24° 39.6' N ( 24.66000) LONGITUDE: 81° 25.4' W ( -81.42330)
The bench mark is a disk set flush in the top of the concrete guardrail located
at the east end of the new U.S. Highway 1 bridge over Niles Channel, 5.94 m
(19.5 ft) south of the centerline of the bridge, 1.62 m (5.3 ft) west of the NE
end of the concrete guardrail, and 1 m (3 ft) above the road.
BENCH MARK STAMPING: DOT 9070 E18
DESIGNATION: 872 4255 DOT
MONUMENTATION: Bench Mark disk VM#: 17309
AGENCY: Florida Department of Transportation
(FLDT) IDB PID#:
SETTING CLASSIFICATION: Ground OPUS PID:
LATITUDE: 24° 39.6' N ( 24.66000) LONGITUDE: 81° 25.4' W ( -81.42330)
The bench mark is a disk set into the ground at the east end of the Niles
Channel Viaduct, 1.07 m (3.5 ft) north of a yellow witness post on the south
side of US Highway 1, and 0.15 m (0.5 ft) below ground level.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 5
Station ID: 8724255 PUBLICATION DATE: 03/09/2004
Name: RAMROD KEY
FL
NOAA Chart: 11445 Latitude: 24° 39.6' N ( 24.66000)
USGS Quad: SUMMERLAND KEY Longitude: 81° 25.4' W ( -81.42330)
T I D A L D A T U M S
Tidal datums at RAMROD KEY based on:
LENGTH OF SERIES: 2 MONTHS
TIME PERIOD: January 1974 - February 1974
TIDAL EPOCH: 1983-2001
CONTROL TIDE STATION: 8724580 KEY WEST
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS:
North American Vertical Datum NAVD88 = 0.430
MEAN HIGHER HIGH WATER MHHW = 0.385
MEAN HIGH WATER MHW = 0.310
MEAN SEA LEVEL MSL = 0.172
MEAN TIDE LEVEL MTL = 0.171
MEAN LOW WATER MLW = 0.032
MEAN LOWER LOW WATER MLLW = 0.000
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
NO 1 1937 0.992 0.682
NO 2 1937 3.485 3.175
R 272 1966 0.560 0.250
4255 F 1982 5.875 5.565
4255 G 1982 5.878 5.568
DOT 9070 E18 4.369 4.059
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 5
Station ID: 8724255 PUBLICATION DATE: 03/09/2004
Name: RAMROD KEY
FL
NOAA Chart: 11445 Latitude: 24° 39.6' N ( 24.66000)
USGS Quad: SUMMERLAND KEY Longitude: 81° 25.4' W ( -81.42330)
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 NGS's Integrated Data Base (IDB PID)
provides geodetic datum based on traditionally leveled and bluebooked ties to
the National Spatial Reference System(NSRS) https://www.ngs.noaa.gov/datasheets/.
The NGS Online Positioning User Service (OPUS PID) provides geodetic datum based
on GPS position & tie it to the NSRS https://www.ngs.noaa.gov/OPUS/.
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.