Here you go :
<?php
while($r = mysql_fetch_assoc($res)) {
$lat = urlencode(trim($r['latitude']));
$lng = urlencode(trim($r['longitude']));
$url = 'http://maps.googleapis.com/maps/api/geocode/json?latlng='.$lat.','.$lng.'&sensor=false';
$jsons = @file_get_contents($url);
$data = json_decode($jsons,true);
$address = $data['results'][0]['formatted_address'];
$json [] = array(
"nod" => ucwords($r['driver_name']),
"info" => ucwords($r['driver_name'])."<br />Speed:<b>".$r['current_speed']."Km/h</b>",
"lat" => $r['latitude'],
"lng" => $r['longitude'],
"location" => $address,
"did" => $r['driver_id'],
"mobile_number" => $r['mobile_number'],
"current_speed" => $r['current_speed']." km/h",
"vehicle_name" => $r['vehicle_name'],
"vehicle_number" => $r['registration_number']
);
}
?>