MILEMARK.TXT INTERSTATE MILEMARKERS Document version: 8.6.0 Document dated: Nov 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. Everyone from CB to ham radio uses them. By using this feature built in to APRS, you can easily locate someone simply by reference to their Mile Mark. APRSdos uses the MM.DAT file which represents all the milemarks in the Interstate Highway system. The data is stored as straight line segments between two mile markers. APRSdos uses these to estimate the location of any mile marker in between by interpolation. Only California is excluded because it has no state-wide MM system. 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 th evicinity of the mile mark. USAGE: The Command in APRSdos is MILE-MARKER-VA95-114 for example. This will cause APRSdos to plot a horizontal line at the approximate latitude of the mile marker 114 on interstate I-95 in Virginia (or a circle after ver 860). The intersection of that line with the interstate on the map is the location of mile marker 114. If you entered MM-VA81-56, then APRSdos would plot a vertical longitude line intersecting that interstate approximately where MM 56 should be. Entries in the MILEMARK.DAT file are of the form: VA95,M1,M2,LA1,LA2,LA2,LO2 or VA81,M1,M2,LA1,LA2,LA2,LO2 Where the first field identifies the interstate, and the next two fields give the mile mark at the start and end of a segment of road. The next four fields are the LAT/LONG of these two end points. 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. Notice that a ZIG-ZAG road where the slope of the ZIGS are about the same as the slope of the ZAGS, then the number of feet per mile is the same as a straight line between the end points, and separate road segments are not needed. 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.. MISSING DATA: I have built the entire database for all states with mileage exits since I could get the data from a Highway map, but I need help in those states that dont have mileage exits. Here are the states I cannot do just from maps. I need LAT/LONG of the key mile markers: MA, ME, NH, PA, and NY interstates 81, 88, and 390 In CT, still need I395 at route 2 Norwich I395 at rt 138 or 164 I395 at Mass State line I95 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. If you are driving in these states and can write down the mileage of the key mile markers (those that mark turning points between long straight segments) please send them to me. However, please do not encumber me with lots of little segments. We are just trying to get a rough translation between mile marker and position. The program MILEMARK.EXE will read the MM.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.ALL ------------------------------------------------ Mile marks have also been added to APRStt so that touch-tone users may place them selves on the map anywhere with only a few digit entry. But since this is a complete position, the MILEMARK.DAT file had to be re- done to add LAT and LONG to every reference point. This file is MM.ALL which we will try to maintain as the whole-USA file. This file is then trimmed down by each APRStt SYSOP to match local needs and saved in the local file named MM.DAT (with backup copy named MM.SS for each state or local area). In APRStt, the DTMF entry MMRD#nn will place a station on the map in the vicinity of mile mark nn on road RD. Depending on proximity to other states, the name of the road "RD" can either include the state two letter abbreviation or not depending on whether ambiguities would result on state borders. For example: The entry MD50,0,43,LA1,LO1,LA2,LO2 covers the stretch of Maryland Route 50 starting at mile mark 0 and going to mile mark 43. Since APRStt is a local program, it only needs entry for roads within RF range of APRStt. So only copy over the needed entries from the MM.ALL file to your local MM.DAT file. If there are no adjacent state ambiguities, you may also remove the state abbreviation from the entry to save keystrokes for the APRStt user. BUT if you need to retain the STATE abbreviation to resolve borderline ambiguities, you must convert them to the hashed equivalent DTMF numerical digit. In my case, "MD50" becomes "6350". If you make refinements to MM.DAT, please let me know so I can update the master files. de WB4APR, Bob