Bench Mark Sheet for 8724417, SADDLEBUNCH CHANNEL NO. 4 FL

Superseded Epoch

Large map location marker Station Location
Small red map location marker Published bench mark
Small blue map location marker Unpublished bench mark

Bench mark positions only appear on the map if their coordinates in the CO-OPS database are at the precision of degrees/minutes/seconds/and tenths of seconds. If the coordinates are less precise, the mark will not appear.

Printable version

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
Datums Page                                                        Page  1 of  5

                                                                                
Station ID: 8724417                         PUBLICATION DATE:  01/23/2004
Name:       SADDLEBUNCH CHANNEL NO. 4                         
            FL
NOAA Chart: 11442                           Latitude:   24° 36.9' N (  24.61500)
USGS Quad:  SADDLEBUNCH KEYS                Longitude:  81° 37.0' W ( -81.61670)


To reach the tidal bench marks from the Catholic Church in Key West, proceed
20.0 km (12.4 mi) NE on U.S. Highway 1 to the bridge over Saddlebunch Channel
No. 4.  The bench marks are in the vicinity of the U.S. Highway 1 bridge and the
old bridge (now a fishing pier).  The tide gage and staff were located off
mangroves west of the south wing of the old U.S. Highway 1 bridge (fishing
pier).


                         T I D A L   B E N C H   M A R K S


                 PRIMARY BENCH MARK STAMPING:  NO 1 1974
                         DESIGNATION:          872 4417 TIDAL 1

MONUMENTATION:           Tidal Station disk                    VM#:         9584
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:  AA0772
SETTING CLASSIFICATION:  Concrete wing wall                    OPUS PID:        
LATITUDE:   24° 36.9' N (  24.61500)          LONGITUDE:  81° 37.0' W ( -81.61670)


The primary bench mark is a disk set into the south concrete wing wall of the
old U.S. Highway 1 bridge (now a fishing pier) over Saddlebunch Channel No. 4,
14 m (46 ft) SE of the centerline of the old bridge (fishing pier), and 2.74 m
(9.0 ft) below the old bridge (fishing pier).



                         BENCH MARK STAMPING:  NO 3 1974
                         DESIGNATION:          872 4417 TIDAL 3

MONUMENTATION:           Tidal Station disk                    VM#:         9586
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:  AA0765
SETTING CLASSIFICATION:  Concrete bridge curb                  OPUS PID:        
LATITUDE:   24° 36.9' N (  24.61500)          LONGITUDE:  81° 37.0' W ( -81.61670)


The bench mark is set into the NW curb of the NE end of the old U.S. Highway 1
bridge (now a fishing pier), 3.87 m (12.7 ft) NW of the centerline of the old
bridge (fishing pier).

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  2 of  5

                                                                                
Station ID: 8724417                         PUBLICATION DATE:  01/23/2004
Name:       SADDLEBUNCH CHANNEL NO. 4                         
            FL
NOAA Chart: 11442                           Latitude:   24° 36.9' N (  24.61500)
USGS Quad:  SADDLEBUNCH KEYS                Longitude:  81° 37.0' W ( -81.61670)


                         T I D A L   B E N C H   M A R K S


                         BENCH MARK STAMPING:  4417 F
                         DESIGNATION:          872 4417 F TIDAL

MONUMENTATION:           Bench Mark disk                       VM#:         9588
AGENCY:                  Florida Department of Transportation
                         (FLDT)                                IDB PID#:  AA0764
SETTING CLASSIFICATION:  Concrete bridge guardrail             OPUS PID:        
LATITUDE:   24° 36.9' N (  24.61500)          LONGITUDE:  81° 37.0' W ( -81.61670)


The bench mark is set in the concrete guardrail of the U.S. Highway bridge over
Saddlebunch Channel No. 4, 7.07 m (23.3 ft) SE of the centerline of U.S. Highway
1, (3.17 m) 10.4 ft SW of the NE end of the guardrail, (1.49 ft) 1.5 m NW of the
SE edge of the U.S. Highway 1 bridge cheekwall, 0.27 m (0.9 ft) NE of the NE
abutment, and 1 m (3 ft) above U.S. Highway 1.



                         BENCH MARK STAMPING:  4417 G
                         DESIGNATION:          872 4417 G TIDAL

MONUMENTATION:           Bench Mark disk                       VM#:         9589
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:  AA0766
SETTING CLASSIFICATION:  Concrete bridge guardrail             OPUS PID:        
LATITUDE:   24° 36.9' N (  24.61500)          LONGITUDE:  81° 37.1' W ( -81.61830)


The bench mark is set in the concrete guardrail at the SW end of the U.S.
Highway 1 bridge over Saddlebunch Channel No. 4, 6.98 m (22.9 ft) SE of the
centerline of U.S. Highway 1, 3.14 m (10.3 ft) NE of the SW end of the
guardrail, 1.49 m (4.9 ft) NW of the SE edge of the U.S. Highway 1 bridge
cheekwall, 0.24 m (0.8 ft) SW of the SW abutment, and 1 m (3 ft) above U.S.
Highway 1.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  3 of  5

                                                                                
Station ID: 8724417                         PUBLICATION DATE:  01/23/2004
Name:       SADDLEBUNCH CHANNEL NO. 4                         
            FL
NOAA Chart: 11442                           Latitude:   24° 36.9' N (  24.61500)
USGS Quad:  SADDLEBUNCH KEYS                Longitude:  81° 37.0' W ( -81.61670)


                         T I D A L   B E N C H   M A R K S


                         BENCH MARK STAMPING:  Q 271 1966
                         DESIGNATION:          Q 271

MONUMENTATION:           Bench Mark disk                       VM#:         9590
AGENCY:                  US Coast and Geodetic Survey
                         (USC&GS)                              IDB PID#:  AA0117
SETTING CLASSIFICATION:  Concrete curb                         OPUS PID:        
LATITUDE:   24° 37.0' N (  24.61670)          LONGITUDE:  81° 37.0' W ( -81.61670)


The bench mark is set on the top of the SE concrete curb at the NE end of the
old U.S. Highway 1 bridge (now a fishing pier), 3.51 m (11.5 ft) SE of the
centerline of the old bridge (fishing pier), and 0.3 m (1 ft) above the old
bridge (fishing pier).

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  4 of  5

                                                                                
Station ID: 8724417                         PUBLICATION DATE:  01/23/2004
Name:       SADDLEBUNCH CHANNEL NO. 4                         
            FL
NOAA Chart: 11442                           Latitude:   24° 36.9' N (  24.61500)
USGS Quad:  SADDLEBUNCH KEYS                Longitude:  81° 37.0' W ( -81.61670)


                            T I D A L   D A T U M S 


Tidal datums at SADDLEBUNCH CHANNEL NO. 4 based on:

     LENGTH OF SERIES:      1 MONTH
     TIME PERIOD:           May 1974 - May 1974
     TIDAL EPOCH:           1983-2001
     CONTROL TIDE STATION:  8724580 KEY WEST


Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS:

     MEAN HIGHER HIGH WATER                     MHHW   =  0.326
     North American Vertical Datum              NAVD88 =  0.258
     MEAN HIGH WATER                            MHW    =  0.248
     MEAN TIDE LEVEL                            MTL    =  0.135
     MEAN SEA LEVEL                             MSL    =  0.108
     MEAN LOW WATER                             MLW    =  0.022
     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 1974                                   0.663    0.415
     NO 3 1974                                   3.493    3.245
     4417 F                                      4.797    4.549
     4417 G                                      4.779    4.531
     Q 271 1966                                  3.513    3.265


                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  5 of  5

                                                                                
Station ID: 8724417                         PUBLICATION DATE:  01/23/2004
Name:       SADDLEBUNCH CHANNEL NO. 4                         
            FL
NOAA Chart: 11442                           Latitude:   24° 36.9' N (  24.61500)
USGS Quad:  SADDLEBUNCH KEYS                Longitude:  81° 37.0' W ( -81.61670)


                             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.

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