var northbound_hikers_start_layer = new google.maps.FusionTablesLayer({
  query: {
    select: 'start_lat',
    from: '1JUAkUL5H7IhU4QrmLuVQ65Tg2SNyI5Xqm3A7Nk1g',
    where: "dir = 'Northbound'"
  },
  heatmap: {
    enabled: true
  },
  suppressInfoWindows: false,
  map: map
});