MILEMARK.TXT INTERSTATE MILEMARKERS Document version: 8.6.2 Dec 03 (previous was 30 Aug 2002 Author(s): Bob Bruninga, WB4APR ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ INTRODUCTION: Prior to APRS, Mile markers were and remain the universal mobile radio position location system for all 2-way radio users and services. I consider Milemarks to be a manditory requirement in all APRS systems though it was not in the spec. By using this feature built in to APRS, you can easily locate someone simply by reference to their Milemark. APRSdos uses the MM-DATA.DAT file which has all the milemarks in the Interstate Highway system. The data is stored as straight line segments between two mile markers. APRSdos uses these to interpolate the location of any mile marker in between. Only California is excluded because it has no state-wide MM system (at this time)... In versions prior to 860, APRSdos only used the LATITUDE for north-south segments and LONGITUDE for east-west segments. To display the location it would just draw a horizontal or vertical line and the location of the milemark is the intersection of the line and the road. After version 860, APRSdos draws a 1 mile ambiguity circle in the vicinity of the mile marks every 2nd, 5th or 10th mile mark depending on Range Scale. USAGE: The Command in APRSdos was MILE-MARK-VA95-114 for example to locate the location of MM-114. But in APRSdos version 861, this was further simplified to just MM-VA95 to identify Virgina I-95, and now it simply draws a Mile Mark circle every Nth mile so that you can see them all at once. This is useful for not only fine-tuning the database itself, but also is shorter and lets you see where a mobile is without actually having to enter his mile mark... The OLD format is in MILEMARK.DAT. Version 861 used a temporary format in MM.DAT but the new simplified file format in version 862 with LAT/LONG for each segment is in the MM-DATA.DAT file and is of the form: SS##,MK,LAT,LON Where the SS## identifies the interstate or road (it is a variable length string, so "FL5" or "GA985" are valid) and the next fields give a mile mark and its LAT/LONG. Since the intent of this system is only to locate mile marks within about a mile, the file does not try to follow every single bend in the road but just the general trend of the road. So, concentrate on building the data for the long straight stretches and dont worry about the nooks and crannies. I only used 9 entries for the 400 miles of I-40 through the length of Tennessee.. In ver 862, if you enter SS? for the interstate, APRSdos will list all the interstates in that state and the milemarks in the database. MISSING DATA: These states dont have mile-mark exit numbers so I cannot do them just from maps. I need LAT/LONG of the key mile markers: MA, ME, NH, PA, and NY interstates 81, 88, and 390 CT needs I395 at route 2 Norwich I395 at rt 138 or 164 I395 at Mass State line I 95 at RI state line Note, in NY, the I-87 portion of the NY State Throughway is called NYST to distinguish if from NY87 where mile mark 0 restarts. The program MILEMARK.EXE will read the MM-DATA.DAT file and plot the resulting map. It should look like an interstate map of the USA to make sure it has all the data elements in the right place. APRS-Touch-Tone MILE MARKS USING THE FILE MM-TT.DAT --------------------------------------------------- Mile marks have also been added to APRStt so that touch-tone users may place themselves on the map anywhere with only a few digit entry. This is what drove me to convert from the line-intersection method to the ambiguity circle display now in MM-DATA.DAT. But since APRStt is purely a simplex or one repeater system it is therefor only a local system, and there is no need to include the STATE abbreviation in each road name. So for APRStt, the local APRS-tt SYSOP has to trim down the MM-DATA.DAT file to only the Interstates in range and the state abbreviations are removed, so that VA95 becomes just "95" for example. He should save the trimmed file as MM-TT.SSn for his backup copy and then copy it to the generic name of MM-TT.DAT so that APRS-tt can find it. In APRStt, the DTMF entry MMRD#nn will place a station on the map in the vicinity of mile mark nn on road RD. Even with the state abbreviation removed, there is no ambiguity because mile marks always go from west to east and south to north. So the end of the interstate in one state and beginning in the next are always significantly different milemark numbers. Thus the data base at any single APRS-tt application can easily differentiate between the two. If you find any errors or make refinements to MM-DATA.DAT, please let me know so I can update the master files. de WB4APR, Bob