The sunrise sky is fine,... actually great. As dark as it must have been there probably wasn't much light on the bridge to gather in, but to get the benefit of HDR you had to get more shots on the opened up end. Since you had the camera on a tripod, after you shot the first burst of three you could have just jumped down a few stops on compensation and shot another burst.
It's tough to make a great shot when the sky is all you have. It would have been better if there was a location where you could have gotten some other elements in the scene which would have led your viewer around the picture, and perhaps give more reflection of the sunrise on the water.