Israeli Transverse Mercator

Israeli Transverse Mercator (ITM), also known as the New Israel Grid (NIG; Hebrew: רשת ישראל חדשה, רשת ישראל החדשה Reshet Yisra'el Ha-Ḥadasha) is the new geographic coordinate system for Israel. The name is derived from the transverse Mercator projection it uses and the fact that it is optimized for Israel. ITM has replaced the old coordinate system Israeli Cassini Soldner (ICS), also known as the Old Israel Grid (OIG). It became the official grid for Israel in 1998.[1]

Israeli Transverse Mercator - ITM
Geodesy
Fundamentals
Concepts
Technologies
Standards (history)
NGVD 29 Sea Level Datum 1929
OSGB36 Ordnance Survey Great Britain 1936
SK-42 Systema Koordinat 1942 goda
ED50 European Datum 1950
SAD69 South American Datum 1969
GRS 80 Geodetic Reference System 1980
ISO 6709 Geographic point coord. 1983
NAD 83 North American Datum 1983
WGS 84 World Geodetic System 1984
NAVD 88 N. American Vertical Datum 1988
ETRS89 European Terrestrial Ref. Sys. 1989
GCJ-02 Chinese obfuscated datum 2002
Geo URI Internet link to a point 2010

The need for a new grid

ITM replaced the Old Israel Grid (OIG) (Hebrew: רשת ישראל ישנה), also known as the Israel Cassini Soldner (ICS), which was based on the Cassini-Soldner projection. ICS in turn was a simple modification of the Palestine grid used during the British mandate. The central meridian in the new projection, as in the old one, crosses through Jerusalem. The new grid has two main advantages. One is that the Transverse Mercator projection is better for navigation than Cassini-Soldner. The other is that ICS was based on a 19th-century reference ellipsoid (approximation of the shape of the Earth) and this was replaced by a more accurate approximation.

Additional information on the creation of the new grid is available in Hebrew.[2]

Examples

An ITM coordinate is generally given as a pair of six digit numbers (excluding any digits behind a decimal point which may be used in very precise surveying). The first number is always the Easting and the second is the Northing. The easting and northing are in metres from the false origin.

The ITM coordinate for the Western Wall at Jerusalem is 222286 632556, which means

E 222286 m
N 631556 m

The first figure is the easting and means that the location is 222,286 meters east from the false origin (along the X axis). The second figure is the northing and puts the location 631,556 meters north of the false origin (along the Y axis). Also notice how the easting in this example is indicated with an “E” and likewise an “N” for the northing.

The table below shows the same coordinate in 3 different grids:

Grid Easting Northing
ITM (Israeli Transverse Mercator) 222286 631556
ICS (Israeli Cassini-Soldner) 172249 1131586
UTM (Universal Transverse Mercator) 711563 3518045

Grid Parameters

The ITM coordinate system is defined[3] by the following parameters:

Projection

Transverse Mercator

Reference ellipsoid

EllipsoidGRS80
Semi-major axis a6378137.000meter
Inverse flattening (1/f)298.257222100882711

Origin Point

Latitude31° 44' 03.8170" N
Longitude35° 12' 16.2610" E

False Origin

False Easting219529.584meter
False Northing626907.390meter
Scale Factor1.0000067

Parameters for conversion to WGS84

Reference ellipsoid

EllipsoidWGS84
a6378137meter
1/f298.257223563

Shift

dX-24.0024meter
dY-17.1032meter
dZ-17.8444meter

Rotation

X-0.33077sec
Y-1.85269sec
Z1.66969sec

Scale

Scale5.4248ppm

See also

References
  1. Survey of Israel. "Important dates in the history of the Survey of Israel".
  2. "New Grid for Israel", in Hebrew, retrieved September 27, 2007, about the New Israeli Grid, published by the Mapping Center of Israel (MAPI) in the official website
  3. Survey Regulations 2016, p. 36 (1378)
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