function showPowerLines() {
  map.addOverlay(PowerLines);
  for (var i = 0; i < powerlineMarkers.length ; i++) {
    map.addOverlay(powerlineMarkers[i])
    }
	}

function hidePowerLines() {
  map.removeOverlay(PowerLines);
  for (var i = 0; i < powerlineMarkers.length ; i++) {
    map.removeOverlay(powerlineMarkers[i])
    }
	}

var PowerLines = new GPolyline([
  new GLatLng(51.5698765912739, 0.621672243340752),
  new GLatLng(51.5681169253866, 0.629800534070994) ],
  powerlineColours[0], 2);


var powerlinePositions = new Array();
  powerlinePositions = [
  new GLatLng(51.5691628284753, 0.624573736536253),
  new GLatLng(51.5683896172226, 0.628695005298758),
];

var powerlineNames = new Array();
  powerlineNames = [
'<h4>Looking East</h4><p><img src="Markers/UnderPylons2.jpg" alt="Under the pylons, looking East" width="127" height="180" /></p>', 
	"Looking West"
	];

var powerlineImages = new Array();
  powerlineImages = ["PL", "PL"];

// Creates a  marker whose info window displays the name corresponding
// to the given index.
function createpowerlineMarker(point, index) {
  // Create an icon for this point using our icon class
  var thisIcon = new GIcon(mapIcon);
  var imageName = "Markers/" + powerlineImages[index] + ".png";
    thisIcon.image = imageName;

  // Set up our GMarkerOptions object
  var markerOptions = { icon:thisIcon };
  var marker = new GMarker(point, markerOptions);

  GEvent.addListener(marker, "click", function() {
    marker.openInfoWindowHtml(powerlineNames[index]);
  });
  return marker;
}

// Create Markers with point from powerlinePositions.js
var powerlineMarkers = new Array();
for (var i = 0; i < powerlinePositions.length; i++) {
  powerlineMarkers[i] = createpowerlineMarker(powerlinePositions[i],i);
  }