The Harris cars ex suburban to conversion to VLP commuter cars in early 1980's did not come about as a result of wooden bodied cars being condemned, nor was their conversion a short term expectation lifewise.
In the late 1970's the VLP had not built a single new country car for over 28 years, there was only a handful of S & Z class and a few BE air con cars. The Walker railmotors were falling to bits, and the four modern Tulloch DRC were not terribly reliable.
VR and Government of the day were faced with a decision to invest in country rail passenger or get out of the business.
Prior to all this 30 N cars had been ordered for the Geelong line, and later 6 were added for the Ballarat line (as a result of a by election !).
It was subsequently decided to upgrade and retain the country passenger service. The key elements of a capital upgrade program were track alterations at plat 7 Spencer St and a run around road at Sth Geelong, the order for N cars was extended from 36 to 54 and ultimately 57. The S & Z cars were refurbished, 39 Harris suburban trailer cars were converted to H cars, 11 new N class locos were ordered, and the 26 B class were to be rebuilt as A class. Further 13 first series T class were to be rebuilt with HEP (as P class) to go with the 13 x 3 car H sets. Also it was proposed to rebuild / upgrade the ten DERM's.
The H cars were intended to be made up as 13 x 3 car sets hauled by a P class loco, or could be doubled up as double consists in a push/pull configuration.
The expected life of the H cars , and P locos was projected as 20 - 25 years. (So they are nearing the end of their use within 5 years ideally from now.)
From October 1981 train frequencies were increased by one third and train operations were altered to fixed consist working. This had the immediate effect of reducing the carriage fleet from 360 wooden bodied cars to well under 100 on that one day .
Until 1983/84 wooden bodied cars still made up a fair part of the fixed consists, and as the N & H cars arrived the wooden bodied E & W cars were progressively retired as planned. (It is interesting to note that in their last years these cars were running over 1000kms per day on plain journal bearings at 115kmh, well in excess of the average 260 kms per day they had previously run. )
Subsequently the N class order was extended from to 26 new units and the B to A class re-builds were cut back to 11. Also the planned upgrading of the DERM's was not proceeded with owing to the age of the units and their heavy body weight .
Since the initial 39 H car conversions , further conversions have been done up to a total 55 H cars . In the first instance the BIH car (intermediate car with no toilet) was built and added to make 4 car sets.
These sets have been re-configured several times very ingeniously to currently make up 3, 4 & 5 car sets.
Configuration of H sets is constrained to some degree by some cars having fixed draw bars, and others auto coupled , plus HEP limitations through cabling capacity.