You don't populate the path coordinates in the right way, the full red color lines are lines repeted more and more time and the 50% opacity lines are lines draw one time only, this mean same coordinate are repeted. Probably you are loading the coordinates in path in wrong way or in wrong sequence. Or You are trying to draw more lines but for mistake you draw one or few lines wrong. The code you are provide is not enough for a correct evaluation. probably is necessary evalute the coordinates of marker too.
I have played with your code and this is a functioning and self-consistent code page
I have found some minor mistake in coding eand some declaration i preferred move in top of the script. Essentially the problem are the coordinates of the points in many case the coordinates refer to the same line in reverse order or start for the same point and are very near each other. Probabily you need to clear the double lines (i have signed some) and define better whiat you want show in the map.
I hope this is useful for you
<!DOCTYPE html>
<html>
<head>
<title>test sandbox 8</title>
<style type="text/css">
#main {
margin: 60px 15px;
}
#map {
min-height: 600px;
min-width: 800px;
}
</style>
<script src="http://maps.google.com/maps/api/js?v=3&sensor=false" type="text/javascript"></script>
<script>
// code to draw map
var map;
var col = '#FF0000';
var link ;
var latLng;
var polypoints;
function initialize() {
var mapProp = {
center : new google.maps.LatLng(53.40, -2.99),
zoom : 12,
mapTypeId : google.maps.MapTypeId.ROADMAP
};
map = new google.maps.Map(document.getElementById("map"), mapProp);
// data to show the links between locations, first part of lat & long denotes from location and second part is to location for a link.
var links_data = [
{"path":[{"lat":53.408123,"lng":-2.985655},{"lat":53.416366,"lng":-2.985655}]},
{"path":[{"lat":53.416366,"lng":-2.985655},{"lat":53.408123,"lng":-3.038971}]},
{"path":[{"lat":53.409477,"lng":-2.982685},{"lat":53.390648,"lng":-3.014405}]},
{"path":[{"lat":53.390648,"lng":-3.014405},{"lat":53.409477,"lng":-2.982685}]},
{"path":[{"lat":53.407086,"lng":-2.989244},{"lat":53.390648,"lng":-3.014405}]},
{"path":[{"lat":53.390648,"lng":-3.014405},{"lat":53.407086,"lng":-2.989244}]},
{"path":[{"lat":53.409477,"lng":-2.982685},{"lat":53.407086,"lng":-2.989244}]},
{"path":[{"lat":53.409477,"lng":-2.982685},{"lat":53.409477,"lng":-2.982685}]},
{"path":[{"lat":53.389557,"lng":-2.989244},{"lat":53.388615,"lng":-3.015866}]}, // line 9 same origin of line 13
{"path":[{"lat":53.388615,"lng":-3.015866},{"lat":53.409477,"lng":-2.982685}]}, // line 10 same origin of line 13
{"path":[{"lat":53.388615,"lng":-3.015866},{"lat":53.407086,"lng":-2.989244}]}, // line 11
{"path":[{"lat":53.409477,"lng":-2.982685},{"lat":53.389557,"lng":-3.014986}]}, // line 12
{"path":[{"lat":53.388615,"lng":-3.015866},{"lat":53.390648,"lng":-3.014405}]}, // line 13
{"path":[{"lat":53.389557,"lng":-3.014405},{"lat":53.389557,"lng":-3.022483}]}, // line 14
{"path":[{"lat":53.408123,"lng":-3.038971},{"lat":53.410152,"lng":-3.022483}]}, // line 15 repeat line 17 in reverse order
{"path":[{"lat":53.416366,"lng":-2.985655},{"lat":53.410152,"lng":-3.022483}]}, // line 16 repeat line 18 in reverse order
{"path":[{"lat":53.410152,"lng":-3.022483},{"lat":53.408123,"lng":-3.038971}]}, // line 17
{"path":[{"lat":53.410152,"lng":-3.022483},{"lat":53.416366,"lng":-2.985655}]} // line 18
];
// draw links
for(var i = 0 ; i < links_data.length; i++)
{
latLng = links_data[i].path;
// polylines lat long array
polypoints = [];
for ( var j = 0; j < latLng.length; j++) {
polypoints[j] = new google.maps.LatLng(
parseFloat(latLng[j].lat),
parseFloat(latLng[j].lng));
}
link = new google.maps.Polyline({
path : polypoints,
geodesic : true,
strokeColor : col,
strokeOpacity : 0.5,
strokeWeight : 3,
title : "test"
});
link.setMap(map);
}
}
google.maps.event.addDomListener(window, 'load', initialize);
</script>
</head>
<body>
<div id="map"></div>
</body>
</html>
