During the forthcoming blockade at Lincoln to upgrade the track layout, there will be lots of engineers trains in operation, so Lincoln will be a good place to photograph the action. A road overbridge and a footbridge should give a good view of the engineering work.
A few recent pictures. By the look of the trackage, some of it is in dire need of replacement!
http://images.fotopic.net/ypwnza.jpg
http://images.fotopic.net/yoyr32.jpg
http://images.fotopic.net/ypwnzg.jpg
http://images.fotopic.net/yoyr2z.jpg