Overall the model is good, but there are areas that needs more attention to detail and good modeling practice. I'm busy rigging the excavator arm now and the cylinder and rod end eyes are not aligned properly with the cylinder centre lines. Some of the cylinders were scaled and x form not reset, so when you rotate them they go oval shape. There are several curved surfaces with incorrect smoothing, either the curve is not smoothed or it is smoothed with badly aligned surfaces causing bad renders. On the positive side there is nice overall detail on the model such as wires and hoses. The tracks also look good and the handrails and stairs are all there.