/// <summary>
        /// Load the providers from the web.config.
        /// </summary>
        private static void LoadProviders()
        {
            // Avoid claiming lock if providers are already loaded
            if (_provider == null)
            {
                lock (_lock)
                {
                    // Do this again to make sure _provider is still null
                    if (_provider == null)
                    {
                        // Get a reference to the <blogProvider> section
                        TrainProviderSection section = (TrainProviderSection)WebConfigurationManager.GetSection("TrainEngine/TrainProvider");

                        // Load registered providers and point _provider
                        // to the default provider
                        _providers = new TrainProviderCollection();
                        ProvidersHelper.InstantiateProviders(section.Providers, _providers, typeof(TrainProvider));
                        _provider = _providers[section.DefaultProvider];

                        if (_provider == null)
                        {
                            throw new ProviderException("Unable to load default TrainProvider");
                        }
                    }
                }
            }
        }
        /// <summary>
        /// Load the providers from the web.config.
        /// </summary>
        private static void LoadProviders()
        {
            // Avoid claiming lock if providers are already loaded
            if (_provider == null)
            {
                lock (_lock)
                {
                    // Do this again to make sure _provider is still null
                    if (_provider == null)
                    {
                        // Get a reference to the <blogProvider> section
                        TrainProviderSection section = (TrainProviderSection)WebConfigurationManager.GetSection("TrainEngine/TrainProvider");

                        // Load registered providers and point _provider
                        // to the default provider
                        _providers = new TrainProviderCollection();
                        ProvidersHelper.InstantiateProviders(section.Providers, _providers, typeof(TrainProvider));
                        _provider = _providers[section.DefaultProvider];

                        if (_provider == null)
                            throw new ProviderException("Unable to load default TrainProvider");
                    }
                }
            }
        }