Paddy Joyce hopes to send more than 5,000 letters by the end of the year.
Fees will be suspended at the three remaining hospitals that still charge for parking.
The marked car he was driving was involved in a smash with another car
The smash happened on the approach to the Kingston Bridge at around 10.40am.
A 51-year-old man has been treated for his injuried following the unprovoked attack on Friday.
A 41-year-old man has been treated at Glasgow Royal Infirmary for stab wounds.
The 33-year-old was seriously injured in the 'unprovoked attack' in Glasgow city centre.
