p1_l (Engine Change)
https://upload.wikimedia.org/wikipedia/commons/9/9a/Desert_KC-10_engine_change.jpg

p2_l (Infrastructure Monitoring Train)
https://www.flickr.com/photos/kecko/47599942152/
Kecko

p3_l (Drone wind turbine inspection)
Many sources on internet without license specifications

p4_l (Train)
https://unsplash.com/photos/5JXSl_raglA
Photo by Uwe Conrad on Unsplash