Refactoring class to get rid of switch case
<p>Say I have a class like this for calculating the cost of travelling different distances with different modes of transportation:</p>

<pre><code>public class TransportationCostCalculator
{
    public double DistanceToDestination { get; set; }

    public decimal CostOfTravel(string transportMethod)
    {
        switch (transportMethod)
        {
            case "Bicycle":
                return (decimal)(DistanceToDestination * 1);
            case "Bus":
                return (decimal)(DistanceToDestination * 2);
            case "Car":
                return (decimal)(DistanceToDestination * 3);
            default:
                throw new ArgumentOutOfRangeException();
        }
    }
</code></pre>

<p>This is fine and all, but switch cases can be a nightmare to maintenance wise, and what if I want to use airplane or train later on? Then I have to change the above class. What alternative to a switch case could I use here and any hints to how?</p>

<p>I'm imagining using it in a console application like this which would be run from the command-line with arguments for what kind of transportation vehicle you want to use, and the distance you want to travel:</p>

<pre><code>class Program
{
    static void Main(string[] args)
    {
        if(args.Length &lt; 2)
        {
            Console.WriteLine("Not enough arguments to run this program");
            Console.ReadLine();
        }
        else
        {
            var transportMethod = args[0];
            var distance = args[1];
            var calculator = new TransportCostCalculator { DistanceToDestination = double.Parse(distance) };
            var result = calculator.CostOfTravel(transportMethod);
            Console.WriteLine(result);
            Console.ReadLine();
        }
    }
}
</code></pre>

<p>Any hints greatly appreciated!</p>