The Sugar Land Railroad was one of several subsidiaries under the Sugarland Industries holding company. It has a convoluted history, which I'll save for a later date. The railroad owned several engines and at least one private car for William T. Eldridge's personal use. I hope to have more on those items, too. What I've got now is a picture of the round house where they moved/rotated engines on various tracks.
Here's a photo of an engine near near the round house. Notice its antique configuration; for example, its smoke stack is fairly high for the size of the engine, which is relatively small. As far as I know, these engines never ran on the Southern Pacific tracks that parallel Highway-90A.
David Chernosky has pointed out the location of the round house. I was surprised to learn it sat between the old John Deere building and Cleveland Lake. I've marked an aerial photo below. Eldridge kept his rail car in a shed by the round house. It may be the same building where the arrow points in the aerial photo. I'll have to talk with David about this.