I have a feeling the photo thread just isn't that viable anymore. SSP no longer has a lock on urban photo tours. Follow anyone on instagram in your city of choice and you can get daily/hourly photo updates, often of a higher quality than the large memory card dumps that sometimes happen here.
I had some suggestions a while back about the aesthetics of how the photo threads could be presented, large thumbs instead of text. Something just like this:
http://www.globalyodel.com/
The idea of a photothread map:
http://www.globalyodel.com/map/
Text based links and hard to construct. BBC code has no visual flare in a web where nearly everything is visual, and it is entirely too cumbersome to curate, construct and edit.
I think what the globalyodel site is doing well, is that they only allow a yodel (name could be better) to show 10 photos. It forces the photographer to curate and display their best shots. I don't think people have an attention span for 100 photos, especially if they are SOOC, multiple shots from inside the car of the same building.
If you want more engagement, show less. If someone posts 100 photos, there will be some good shots, but there will be a lot of mediocre shots. What will commenters say? Nice shots, great photos. It's too hard for a viewer to pick out the good ones from the noise. But, if there are only 10, each photo can be looked at more closely, and maybe commented on more specifically.
A yodel is almost like getting to know your SSP photogs mixed with a short curated photo thread. I think this is the direction SSP would have to move if it wanted to draw more attention and feedback from its users. However, since it is constrained by BBC, I don't think that is possible to make it look like a flashy web 3.0 site. But, there is the option to making a new section, (My City Tour?, My City Showcase?) that would highlight certain threads and photographers. Have a new one every few weeks, limit the number of photos, and have some interview questions, not just about the photographer and their intentions, but also the photographer's connection to the place they are showcasing.