There are independent studies at the link.
I tried to link directly to the page, but they evidently want you to go through their home page first.
1/3 of the way down, on the right is a box called "Popular Studies". Click on "Red Light Camera Roundup". There are dozens of independent studies in PDF format.
Sheesh.
I looked through the "studies" and "commentary" listed on the website and still don't see any independent engineering studies there. Everyone there has their own axe to grind.
If it is NOT from a national engineering group (like the ASCE) and has been peer reviewed and accepted by the people actually working in the field, it is suspect. There may be some ivory-tower, pin-heads out there who are actually doing good work, but that has to be proved, not just accepted.