LADOTD - Convert Latitude/Longitude to Route or Control-Section
Revised as of September 2015
This program will convert locations from any one of the following reference
systems to the others:
3. lrs id/lrs logmile
5. accident route/milepost
6. utm zone 15
Which conversion it does depends on the button you press.
The route and milepoint are those used on the LADOTD Surface-Type Log file.
The milepoint is the measured distance from the beginning of the route to the point
The route and milepost are those used in the LADOTD Surface-Type Log file
for cross-referencing traffic accidents according to the milepost markers
on the road.
Control-Section / Logmile
The control-section and logmile are those defined by the LADOTD Control-Section
manual and the LADOTD Surface-Type Log file.
LRS ID / Distance
The LRS ID is described by the document "LRS_ID_Procedure.doc". It is the new way
at LADOTD of defining road segments. The distance associated with the LRS ID is in
the direction of travel on the road segment. The corresponding control-section/logmile
and route/milepoint are those belonging to the main line of the roadway that is
closest to the point in question.
The latitude/longitude may be input as:
DD.DDDDD - whole degrees and decimal parts of degrees
DD:MM.MMM - whole degrees, whole minutes and decimal parts of minutes.
DD:MM:SS.SS - whole degrees, whole minutes, and seconds.
If you use the second or third options, you must use a space or a
colon(:) as a separator.
The route may be input as (for example:)
A0010 - for I-10
I-10 - for I-10
US0080 - for US 80
B0080 - for US 80
LA3246 - for LA 3246
C3246 - for LA 3246
US0190X - for US 190 business
You may be confused by the "A,B,C" designation. This is the way the
Department of Public Safety identifies Interstate, U.S., and Louisiana
highways. The option is included for ease of interfacing with their system.
The output formats are selected by the radio buttons. They are similar to
the input formats.
The accuracy of the results varies. In some cases, it will hit it on
the head. In others, it may be off by a half a mile. I'm working on
improving the data. Also, the latitude and longitude are stored with
only 5 decimal places of accuracy (7 digits total). The route
information is stored to the nearest .001 miles, but is displayed using
the nearest .01 mile.
Source of Data
The route and control-section cross-reference data are from the LADOTD
Surface-Type Log File.
The latitude/longitude data by control-section logmile was obtained
from the LADOTD mapping section in the form of an ESRI geodatabase.
The UTM conversions are calculated.
Converting latitude/longitude to control-section/logmile
The source data set contains a set of line segments no more thatn 0.1
mile long for each control-section. Each segment contains the
control-section, beginning logmile, ending logmile,
beginning latitude, ending latitude, beginning longitude,
and ending longitude.
The program finds the line segment segment closest to the
target point (based on the latitude and longitude) and draws a
perpendicular to that line. The logmile is then calculated.
If the intersection rule is applied, the second
closest line segment is found. If it is on another route and meets the
intersection rule requirements, that segment is used instead.
If a traffic crash (accident) occurs at an intersection, the location is
assigned to the lowest numbered route. If the intersection includes the
interstate and a U.S. highway, the interstate takes priority. If the
intersection includes a U.S. highway and a LA highway, the U.S. highway
takes priority. If the intersection includes a business route and a
"non-business" route at the same level (US, LA), the "non-business" route
For the intersection rule to apply, the location must be no more than 150
feet away from the "other" route.
Glenn Chustz - LADOTD - April 17, 2002
UTM/DOQQ Revisions - November 11, 2002
The UTM coordinates were added as an option. This will
convert the data from latitude/longitude to utm zone 15 coordinates in
meters. It also creates a link to the DOQQ that contains the location.
The UTM to lat/long conversion calculations in this program were copied from the
National Geodetic Survey (NGS)
program named UTMS, available from the web site
http://www.ngs.noaa.gov/TOOLS/utm.shtml which also has
an interactive mode which allows you to do the same calculations.
A useful resource is the NGS Geodetic Toolkit:
This program is in no way intended to replace the Department's GIS tools.