SZCTW Grid

Attributes

Unit: metre

Geodetic CRS: SZCTW-IRF

Datum: SZCTW Intermediate Reference Frame

Ellipsoid: GRS 1980

Prime meridian: Greenwich

Data source: EPSG

Information source: Severn Partnership on behalf of Civil Works Alliance / AtkinsRealis.

Revision date: 2026-05-19

Scope: Engineering survey, GIS, topographic mapping.

Remarks: The CRS's definition through transformation ETRS89-GBR [OSNet v2009] to SZCTW-IRF (1) (code 11467) and map projection SZCTW-TM (code 11468) emulates the SZCTW Snake projection applied to ETRS89 as realized through OSNet v2009. Snake Grid initially designed to cover the rail corridor to the site along with a section of the adjoining mainline for compliance with request from Network Rail, but its use was later expanded for site surveying more generally to replace multiple local grids.

Area of use: United Kingdom (UK) - Sizewell power station site and rail and road routes related to the site.

Coordinate system: Cartesian 2D CS. Axes: easting, northing (E,N). Orientations: east, north. UoM: m.

Covered area powered by MapTiler

Center coordinates
75487.56 49826.39

Projected bounds:
63498.97 35917.24
87466.57 63754.1

WGS84 bounds:
1.35 52.13
1.7 52.38

United Kingdom (UK) - Sizewell power station site and rail and road routes related to the site.

Definition: OGC Well Known Text

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PROJCS["SZCTW Grid",
    GEOGCS["SZCTW-IRF",
        DATUM["SZCTW_Intermediate_Reference_Frame",
            SPHEROID["GRS 1980",6378137,298.257222101,
                AUTHORITY["EPSG","7019"]],
            AUTHORITY["EPSG","1461"]],
        PRIMEM["Greenwich",0,
            AUTHORITY["EPSG","8901"]],
        UNIT["degree",0.0174532925199433,
            AUTHORITY["EPSG","9122"]],
        AUTHORITY["EPSG","11466"]],
    PROJECTION["Transverse_Mercator"],
    PARAMETER["latitude_of_origin",52.25],
    PARAMETER["central_meridian",1.55],
    PARAMETER["scale_factor",1],
    PARAMETER["false_easting",77194.7386],
    PARAMETER["false_northing",49269.7375],
    UNIT["metre",1,
        AUTHORITY["EPSG","9001"]],
    AXIS["Easting",EAST],
    AXIS["Northing",NORTH],
    AUTHORITY["EPSG","11469"]]

Definition: OGC Well Known Text 2 (2019)

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PROJCRS["SZCTW Grid",
    BASEGEOGCRS["SZCTW-IRF",
        DATUM["SZCTW Intermediate Reference Frame",
            ELLIPSOID["GRS 1980",6378137,298.257222101,
                LENGTHUNIT["metre",1]]],
        PRIMEM["Greenwich",0,
            ANGLEUNIT["degree",0.0174532925199433]],
        ID["EPSG",11466]],
    CONVERSION["SZCTW-TM",
        METHOD["Transverse Mercator",
            ID["EPSG",9807]],
        PARAMETER["Latitude of natural origin",52.25,
            ANGLEUNIT["degree",0.0174532925199433],
            ID["EPSG",8801]],
        PARAMETER["Longitude of natural origin",1.55,
            ANGLEUNIT["degree",0.0174532925199433],
            ID["EPSG",8802]],
        PARAMETER["Scale factor at natural origin",1,
            SCALEUNIT["unity",1],
            ID["EPSG",8805]],
        PARAMETER["False easting",77194.7386,
            LENGTHUNIT["metre",1],
            ID["EPSG",8806]],
        PARAMETER["False northing",49269.7375,
            LENGTHUNIT["metre",1],
            ID["EPSG",8807]]],
    CS[Cartesian,2],
        AXIS["(E)",east,
            ORDER[1],
            LENGTHUNIT["metre",1]],
        AXIS["(N)",north,
            ORDER[2],
            LENGTHUNIT["metre",1]],
    USAGE[
        SCOPE["Engineering survey, GIS, topographic mapping."],
        AREA["United Kingdom (UK) - Sizewell power station site and  rail and road routes related to the site."],
        BBOX[52.13,1.35,52.38,1.7]],
    ID["EPSG",11469]]

Definition: ESRI Well Known Text

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PROJCS["SZCTW_Grid",
    GEOGCS["GCS_SZCTW-IRF",
        DATUM["D_SZCTW_Intermediate_Reference_Frame",
            SPHEROID["GRS_1980",6378137.0,298.257222101]],
        PRIMEM["Greenwich",0.0],
        UNIT["Degree",0.0174532925199433]],
    PROJECTION["Transverse_Mercator"],
    PARAMETER["False_Easting",77194.7386],
    PARAMETER["False_Northing",49269.7375],
    PARAMETER["Central_Meridian",1.55],
    PARAMETER["Scale_Factor",1.0],
    PARAMETER["Latitude_Of_Origin",52.25],
    UNIT["Meter",1.0]]

Definition: PROJ.4

+proj=tmerc +lat_0=52.25 +lon_0=1.55 +k=1 +x_0=77194.7386 +y_0=49269.7375 +ellps=GRS80 +units=m +no_defs +type=crs

Definition: JavaScript (Proj4js)

proj4.defs("EPSG:11469","+proj=tmerc +lat_0=52.25 +lon_0=1.55 +k=1 +x_0=77194.7386 +y_0=49269.7375 +ellps=GRS80 +units=m +no_defs +type=crs");

Definition: JSON

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{
    "$schema": "https://proj.org/schemas/v0.7/projjson.schema.json",
    "type": "ProjectedCRS",
    "name": "SZCTW Grid",
    "base_crs": {
        "type": "GeographicCRS",
        "name": "SZCTW-IRF",
        "datum": {
            "type": "GeodeticReferenceFrame",
            "name": "SZCTW Intermediate Reference Frame",
            "ellipsoid": {
                "name": "GRS 1980",
                "semi_major_axis": 6378137,
                "inverse_flattening": 298.257222101
            }
        },
        "coordinate_system": {
            "subtype": "ellipsoidal",
            "axis": [
                {
                    "name": "Geodetic latitude",
                    "abbreviation": "Lat",
                    "direction": "north",
                    "unit": "degree"
                },
                {
                    "name": "Geodetic longitude",
                    "abbreviation": "Lon",
                    "direction": "east",
                    "unit": "degree"
                }
            ]
        },
        "id": {
            "authority": "EPSG",
            "code": 11466
        },
        "remarks": "Intermediate CRS created in 2026 to assist the emulation of the ETRS89 / SZCTW SnakeGrid projected CRS through transformation ETRS89-GBR [OSNet v2009] to SZCTW-IRF (1) (code 11467) used in conjunction with the SZCTW-TM map projection (code 11468)."
    },
    "conversion": {
        "name": "SZCTW-TM",
        "method": {
            "name": "Transverse Mercator",
            "id": {
                "authority": "EPSG",
                "code": 9807
            }
        },
        "parameters": [
            {
                "name": "Latitude of natural origin",
                "value": 52.25,
                "unit": "degree",
                "id": {
                    "authority": "EPSG",
                    "code": 8801
                }
            },
            {
                "name": "Longitude of natural origin",
                "value": 1.55,
                "unit": "degree",
                "id": {
                    "authority": "EPSG",
                    "code": 8802
                }
            },
            {
                "name": "Scale factor at natural origin",
                "value": 1,
                "unit": "unity",
                "id": {
                    "authority": "EPSG",
                    "code": 8805
                }
            },
            {
                "name": "False easting",
                "value": 77194.7386,
                "unit": "metre",
                "id": {
                    "authority": "EPSG",
                    "code": 8806
                }
            },
            {
                "name": "False northing",
                "value": 49269.7375,
                "unit": "metre",
                "id": {
                    "authority": "EPSG",
                    "code": 8807
                }
            }
        ]
    },
    "coordinate_system": {
        "subtype": "Cartesian",
        "axis": [
            {
                "name": "Easting",
                "abbreviation": "E",
                "direction": "east",
                "unit": "metre"
            },
            {
                "name": "Northing",
                "abbreviation": "N",
                "direction": "north",
                "unit": "metre"
            }
        ]
    },
    "scope": "Engineering survey, GIS, topographic mapping.",
    "area": "United Kingdom (UK) - Sizewell power station site and  rail and road routes related to the site.",
    "bbox": {
        "south_latitude": 52.13,
        "west_longitude": 1.35,
        "north_latitude": 52.38,
        "east_longitude": 1.7
    },
    "id": {
        "authority": "EPSG",
        "code": 11469
    }
}

Definition: GeoServer

11469=PROJCS["SZCTW Grid",GEOGCS["SZCTW-IRF",DATUM["SZCTW_Intermediate_Reference_Frame",SPHEROID["GRS 1980",6378137,298.257222101,AUTHORITY["EPSG","7019"]],AUTHORITY["EPSG","1461"]],PRIMEM["Greenwich",0,AUTHORITY["EPSG","8901"]],UNIT["degree",0.0174532925199433,AUTHORITY["EPSG","9122"]],AUTHORITY["EPSG","11466"]],PROJECTION["Transverse_Mercator"],PARAMETER["latitude_of_origin",52.25],PARAMETER["central_meridian",1.55],PARAMETER["scale_factor",1],PARAMETER["false_easting",77194.7386],PARAMETER["false_northing",49269.7375],UNIT["metre",1,AUTHORITY["EPSG","9001"]],AXIS["Easting",EAST],AXIS["Northing",NORTH],AUTHORITY["EPSG","11469"]]

Definition: MapServer - MAPfile

PROJECTION
	"proj=tmerc"
	"lat_0=52.25"
	"lon_0=1.55"
	"k=1"
	"x_0=77194.7386"
	"y_0=49269.7375"
	"ellps=GRS80"
	"units=m"
	"no_defs"
	"type=crs"
END

Definition: Mapnik

<?xml version="1.0" encoding="utf-8"?>
<Map srs="+proj=tmerc +lat_0=52.25 +lon_0=1.55 +k=1 +x_0=77194.7386 +y_0=49269.7375 +ellps=GRS80 +units=m +no_defs +type=crs">
	<Layer srs="+proj=tmerc +lat_0=52.25 +lon_0=1.55 +k=1 +x_0=77194.7386 +y_0=49269.7375 +ellps=GRS80 +units=m +no_defs +type=crs">
	</Layer>
</Map>

Definition: SQL (PostGIS)

INSERT into spatial_ref_sys (srid, auth_name, auth_srid, proj4text, srtext) values ( 11469, 'EPSG', 11469, '+proj=tmerc +lat_0=52.25 +lon_0=1.55 +k=1 +x_0=77194.7386 +y_0=49269.7375 +ellps=GRS80 +units=m +no_defs +type=crs', 'PROJCS["SZCTW Grid",GEOGCS["SZCTW-IRF",DATUM["SZCTW_Intermediate_Reference_Frame",SPHEROID["GRS 1980",6378137,298.257222101,AUTHORITY["EPSG","7019"]],AUTHORITY["EPSG","1461"]],PRIMEM["Greenwich",0,AUTHORITY["EPSG","8901"]],UNIT["degree",0.0174532925199433,AUTHORITY["EPSG","9122"]],AUTHORITY["EPSG","11466"]],PROJECTION["Transverse_Mercator"],PARAMETER["latitude_of_origin",52.25],PARAMETER["central_meridian",1.55],PARAMETER["scale_factor",1],PARAMETER["false_easting",77194.7386],PARAMETER["false_northing",49269.7375],UNIT["metre",1,AUTHORITY["EPSG","9001"]],AXIS["Easting",EAST],AXIS["Northing",NORTH],AUTHORITY["EPSG","11469"]]');

EPSG:11469

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