Google distances using C# - Over-Query-Limit - google-maps

Question

I am trying to fetch google distances in gridview RowDataBound with a force sleep of 1000ms,Nothing helping,Am getting correct distance for the first query,ie the first row of the gridview, all others i get 'Over-Query-Limit' for content variable ,I want to know three things:
Is there any solution for this situation.
Is google limiting queries per day OR
Is google limiting queries per second ?
public int getDistance(string origin, string destination)
{
System.Threading.Thread.Sleep(1000);
int distance = 0;
string url = "http://maps.googleapis.com/maps/api/directions/json?origin=" + origin + "&destination=" + destination + "&sensor=false";
string requesturl = url;
string content = fileGetContents(requesturl);
JObject o = JObject.Parse(content);
try
{
distance = (int)o.SelectToken("routes[0].legs[0].distance.value");
return distance;
}
catch
{
return distance;
}
return distance;
}

Answer 1

Ok,As above 2500 queries per day makes google search a paid service i went for another logic,We can calculate distances without google.com as follows :
public decimal calcDistance(decimal latA, decimal longA, decimal latB, decimal longB)
{
double theDistance = (Math.Sin(DegreesToRadians(latA)) *
Math.Sin(DegreesToRadians(latB)) +
Math.Cos(DegreesToRadians(latA)) *
Math.Cos(DegreesToRadians(latB)) *
Math.Cos(DegreesToRadians(longA - longB)));
return Convert.ToDecimal((RadiansToDegrees(Math.Acos(theDistance)))) * 69.09M * 1.6093M;
}
public double DegreesToRadians(decimal degrees)
{
return Convert.ToDouble((Convert.ToDecimal(Math.PI) / 180.0M) * degrees);
}
public double RadiansToDegrees(double radians)
{
return Convert.ToDouble((180.0M / Convert.ToDecimal(Math.PI)) * Convert.ToDecimal(radians));
}