gps PIM sections breaking on {duration,stop_speed_limit}

sections.js

//js
function haversine(lat1,lon1,lat2,lon2){ 
  var R = 6371; // km

  var dLat = (lat2-lat1) / (360 / (2 * 3.1415926));
  var dLon = (lon2-lon1) / (360 /  (2 * 3.1415926));
  var lat1 = (lat1  / (360 /  (2 * 3.1415926)));
  var lat2 = (lat2 / (360 /  (2 * 3.1415926)));
  
  var a = Math.sin(dLat/2) * Math.sin(dLat/2) +
  Math.sin(dLon/2) * Math.sin(dLon/2) * Math.cos(lat1) * Math.cos(lat2); 
  var c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1-a)); 
  var d = R * c;
  return d;
}


function speeds(checkins){ 
  //like: checkin = {lat,lng,timestamp}; 
  // checkins = [checkin...]; 
  // returns array grouped by timestamp pairs.
  //{[timestamp,latertimestamp] => checkinsFromTimeStampToLaterTimestamp}

  //tweak vars
  var minDrivingSpeed = 5; 
  var maxIdleTimes = 15;

  //what we're here for
  var sections = [];
  var currentCheckinList;
  var sectionedCheckins = {};
  var newSectionedCheckin = function(section){
    var sectionTitle = strftime(section[0], "%H:%M") + ' +' + (section[1] - section[0] / 60) ;
    sectionedCheckins[sectionTitle] = currentCheckins;
    
  };

  //Loop vars
  var idleFor = 60; 
  // assume 1 hour idle - doesn't really matter as
  // long as it's > maxIdleTimes. We start off having been stoppedForAWhile
  var total =checkins.length;

  for(var i=0; i < (total - 1); i++){
    var mph = haversine(checkins[i][0],
                        checkins[i][1],
                        checkins[i+1][0],
                        checkins[i+1][1]
                       ) * 
      1.6 * //km->mi
      60; // updating each min: 60min/hour * miles/min = miles/hour
    var nowDriving = mph > minDrivingSpeed;
    var stoppedForAWhile = idleFor > maxIdleTimes;

    //These are independent
    var stoppedDriving = !nowDriving;
    var startedDriving = nowDriving && stoppedForAWhile;
    var stillDriving = nowDriving && !stoppedForAWhile;

    var currentCheckin = checkins[i];
    var currentSection = sections[sections.length -1];
    var currentTimestamp = checkins[2];
    if(stillDriving){
      currentSection[1] = currentTimestamp;
    }
    if(startedDriving){
      if(currentCheckinList){
        newSectionedCheckin(currentSection);
      }
      currentCheckinList = [currentCheckin];

      sections.push([currentTimestamp, currentTimestamp]);
      idleFor = 0;
    }
    if(stoppedDriving){
      idleFor+= 1;
    } 
      currentCheckinList.push(currentCheckin);
  }
  if(sections[sections.length - 1][1] === checkins[checkins.length -1][2]){ //there's some left
    newSectionedCheckin(sections[sections.length - 1]);
  }
  return sectionedCheckins;
}