I want a well-researched, reader-friendly comparison between the Indian Railways WAP-7 electric locomotive and the WDP-4D diesel twin-cab. The piece should open with a clear overview of why these two machines matter, then dive into hard numbers—horse-power (6 350 HP vs 4 500 HP), top speed, tractive effort, axle load, and acceleration. From there, set the locomotives side-by-side on typical operational contexts: premium electrified corridors for the WAP-7, non-electrified long-distance routes for the WDP-4D, highlighting real-world train examples where possible. Beyond raw performance, include: • Technical specifications: prime mover / traction motor details, gear ratios, braking systems, and control electronics. • Route suitability and turnaround logistics, noting how electrification, rake length, and gradient influence deployment. • Passenger-facing factors such as ride smoothness, noise, and on-board power (hotel load). • Maintenance considerations—major overhauls, spare-part cycles, and typical failure points. Structure the article with clear headings, a neat comparison table, and citation of authoritative sources such as RDSO publications, IR press releases, and reputable rail enthusiast forums. A length of roughly 1 500–1 800 words works well, but feel free to exceed it if the data warrants. Deliverables 1. Editable document (Google Docs, Word, or Markdown). 2. One concise summary table of key specs. 3. A short list of source links for fact-checking. Accuracy is crucial—please cross-verify figures before submission.