Perhaps we need to suspend our disbelief a little further and pretend the trams in Weatherfield are like those in the French city of Nice, and use on-board batteries at selected points where overhead wires would spoil the beauty of an area. Yes, I know Metrolink trams don't have this capacity but then they don't really travel over Coronation Street.
What you are failing to take account of is that the new tram line that goes through Wetherfield is being used for the trial of the new "extralocking" signalling system whereby, should there be a break in the track circuit (or a hint of potential disaster), not only do the signals go red but the OHL is whisked away on spring-loaded reels and the masts sink into the ground. (First designed for use on Channel Tunnel trains routed via Ayr at around the time of Mission Impossible) This reduces the risk of electrocution or meeting an obstruction. Unfortunately, what the designers of the system did not realise is that previous experience of lines passing through areas where filming might take place (eg in King Kong, or Batman Begins) a powerful vacuum is formed over any break in the line or associated works, so the affected train rushes on regardless of how often the driver thumps the brake button
I don't know how the system in Manchester works, but tram routes I know of (London and West Mids) don't have signals outside of points and single track sections; they are driven on line of sight (except of course where they run on-street).
