You studied the photos in greater detail then I, but you appear to be looking for something. I have since noted the trusses on each side are different, and on one side there are two different trusses.
One possibility I did think of, is it may not be Fremantle at all. I cannot tell from the surrounds, but some of these photos may be miss labeled. Some of these are written on the photo itself as being Fremantle, but if your looking for 100% certainty some checking may be required. It is rare however that the photos are mislabed from what I have seen and if the location is in doubt it will be noted.
I have spent quite a lot of time on the ARHS photo page seeing how things use'd to be. I have also spent a lot of time on the TROVE webpage which has old newspaper records. This is VERY helpfull for finding information on when things were changed as it was reported in the newspapers back then. Last night I was researching the SOUTH BUNBURY railway station. TROVE brought up a number of articles regaurding the station and the local residents petitioning for one and contacting the railways about it. I deduced it was near Hennessey Street in Bunbury. I have also learnt about the 1935 Brunswick to Collie railway realignment between Fernbrook and Allanson. Something quite a few people I know in the rail scene didnt know about. Having been to the old alignment it very much was there, with a huge timber bridge, however none of the bridge remains. TROVE takes some care to get what you want, narrow down the newspaper you want, and put some thought in to what your searching for as the right words give the right result. But it is very helpfull.
The ARHS site you need to give it the right words also and use the apostrophe's, and check the boxes but it does work.
Maybe try TROVE for greater detail about the bridge + improvements. They may have added spans to it for increased traffic under the bridge?