I could give you my full one-hour lecture on headlines - gripping, I can assure you - followed by an hour trying to write some to fit tight spaces - always a winner with students - but in short, the idea of a headline is to get people's attention and convey a flavour of the tale, so they read the full story.
They need to be short and snappy - whether in print or on the internet - because if they ramble on for a dozen words, people just give up on reading the headline, never mind looking at the story.
I assume you did read on, so now have the full, rounded picture (hence the 200-plus words that went below the headline). The same goes for members of the 'general public' who read it.
The headline could have said something like 'Cotswold Line preparatory engineering work for doubling up enters final phase for this summer' but most people would just give up after 'preparatory engineering work'.
If you'd like to practise writing some yourselves - half a dozen words or fewer - you could always try conveying the gist of this tale from the Charlbury commuter blog of events at Oxford last Wednesday evening....
18.21 Paddington/19.33 Oxford-Charlbury: 30 minutes' delay
Utter chaos at Oxford where there was a connection to the Moreton train because of the alternative timetable. Due to leave from platform 3, passengers waited for the train to arrive to continue their journey. After 10-15 mins a train pulled in. No announcement to the contrary so people got on it. A few minutes later the train despatcher told everyone to get off: 'not this train, not this train'. A second, two-carriage turbo then arrived and parked in front of the first train. Passengers got on that one: 'not this train, not this train' said the depatcher (no tannoy announcements were happening). Everyone got off again, and watched as the two trains coupled together. Some minutes later the train pulled out of platform 3 empty and stopped a few hundred yards up the train in a siding. Another few minutes passed and it drew back onto platform 3. Everyone got on. After some minutes sitting, the driver announced this was the train for Banbury. Getting off, the display boards no longer showed the Moreton in Marsh train. Still no tannoy announcement was forthcoming. I went to the station concourse to complain, along with some other people. While I was doing this, other passengers were directed to platform 2 over the footbridge. Having made requests for the correct information to be given over a tannoy to a stroppy customer service person who said that he knew what was happening and had been telling everyone(not true), that an order for taxis had been countermanded by central control, that the station manager had left at 7.30 and that there was no-one in charge, we noticed all the passengers trooping over the footbridge back to platform 3. Finally a tannoy announcement stated that the train had not been cancelled and that it was for Moreton after all. It pulled away around 30 minutes late. The guard "could only apologise for the utter shambles". Too right!