Colin do you have this book in your library? If not I highly recommend it. Chapters 6 and 7 pgs 115-152 are all dedicated to the Engineers during the Sicilian Campaign. Maps, text and photos are excellent. This is one book I rely on heavily for research! 
The Corps of Engineers - The War Against Germany - Authors: Alfred M. Beck; Abe Bortz; Charles W. Lynch; Lidia Mayo; And Ralph F. Weld - Publisher: Department of the Army
If you do not have it, one good place to check it out is at Alibris. They are several other used book stores that may have it too and those are also listed there. You may already have your favorites too.
If you do choose to look at Alibris, I would appreciate it if you'd go through my Books Page and click on their ad. They are one of my affiliates and I get a "kick-back" from sales. Thanks! 
Proud Daughter of Walter (Monday) Poniedzialek
540th Engineer Combat Regiment, 2833rd Bn, H&S Co, 4th Platoon
There's "No Bridge Too Far"