Many of these crossings are almost impossible to see from a car because they are so badly sign-posted. There's also the fact that the paint on the crossing has faded in the sun and hasn't been re-painted, plus overhanging tree branches can obliterate the signs. In many cases you need to have the speed of Usain Bolt and the tenacity and ingenuity of an episode of Fear Factor just to make it over to the other side before the lights change.
Only yesterday I witnessed an elderly gentleman trying to cross a road (where the pedestrians are given 10 seconds !) with the aid of two sticks. Needless to say his slowness caused a major traffic snarl-up, which in turn produced a cacophony of car horns sounded by irate and impatient motorists.
If these crossings had Belisha Beacons, which provide additional visibility for the motorist, primarily at night, it might help to keep accidents down to a minimum, that and, of course, drivers who don't go far too fast.
Don't get me started on pedestrians who completely ignore all the signs or lights as they're too busy scanning their latest text messages ! Regards, Monro Bryce