In line with that tradition, from 1979 roughly one in eight of the GY open wagons were selected for conversion to a smaller version of the bogie hopper wagons. GY2207 was modified in March 1979; the sides and ends were removed and a large hole cut into the floor between the axles, to make way for a new hopper unit on the existing underframe with under-floor hatches for unloading. The top of the wagon was sealed, with a trapezoidal roof and walkways fitted for staff who had to open hatches for overhead grain loading. The class eventually numbered 810 units, drawn from all types of steel four-wheel open wagons.
The final variant was to wagon GH800. Rather than using a steel fabricated rooftop, that wagon had a specially cast fibreglass shell constructed and attached, with the intent of reducing the tare weight low enough to avoid frame cracking. However, with introduction in 1982 the modification came too late to have any particular significance, and no other wagons were so modified and the final nine GH wagons entered service using the earlier design.
The railway needed a number of specialised vehicles to carry traffic that could not be easily or safely carried by the standard open, covered or flat wagons. These included strong wagons for metal ingots, etc. ('Totems', diagram B1 etc.); special well wagons for glass sheets ('Coral', D1 and D2) and propellers ('Morel' and 'Aero', E1 etc.). 'Pollens' (A1 etc.) were low single-ended wagons for exceptionally long items such as boilers and girders; they worked in pairs but some could be uncoupled and then one attached to each end of an exceptionally long load, similar to a Schnabel car.
The 1953 General Appendix states that wagons loaded with ignitable goods must be marshalled as close to the front of the train as possible; however, whether loaded or not, a minimum of three other wagons must intervene between the oil or explosives truck(s) and a locomotive, passenger vehicle or other flammable or explosive wagon load, such as hay or detonators respectively. Furthermore, wagons loaded with explosives could not be coupled together, requiring one intermediate safety wagon or three if above a given threshold.
In 1980, two wagons were modified for higher speed operation trials. GH155 and GH336 were fitted with new Gloucester Suspension Unit axleboxes, and trialled at speeds as high as 115 km/h. Given that no further wagons were fitted, it seems likely that the tests showed little to no benefit from faster running.
Parallel to the hopper and brake gear modifications a new arrangement of roof hatches was trialled. The early wagons were fitted with a pair of individual flip-open lids, while later wagons were fitted with a single, much longer rooftop hatch mounted on six hinges.
These rules evolved over time to permit working of block train consists, where a string of oil-carrying wagons would be coupled together with a single bogie safety wagon at either end.
Cattle wagons had a large gap between the top of the sides and the roof, but the ends were similar to vans in that they went right up to the roof. These were for a while built as 'small', 'medium' or 'large' sizes. Later construction was all to the large size but with a moveable partition that could reduce the capacity if that was what a farmer required; if cattle were left with too much space they would hurt themselves if they fell over when the train was in motion. Cattle wagons were given the telegraphic code 'Mex' for ordinary beasts and 'Beetle' for pedigree cattle that needed to be accompanied by a drover, and could be found in diagrams W1 to W14.
Safety wagons were also used either side of oil and explosives vehicles in transit, to reduce the risk of stray sparks from steam locomotives, and between or either end of overlength loads to provide safe coupling points.
The vehicles were rendered obsolete by new bogie grain wagons introduced from the late 1980s, and scrapping ran through to the early 1990s making the class one of the last fixed-wheel vehicles to run in revenue service on the V/Line network.
In the event that loaded explosives wagons needed to be stabled in unattended railway yards, and did not have a functioning hand brake, any ordinary wagon was required to be coupled with its hand brake applied in lieu; or failing that, the wagon was to be chained and locked to the rails through the wheel spokes.
Over time, four-wheeled wagons became obsolete. Bogie vehicles could run at higher speeds and, with more wheels, had a better axle-loading, meaning that they could carry a larger load. A number of classes of bogie vehicles were constructed.
Yards where dangerous goods were handled were often marked with signs to the effect of "ENGINES MUST NOT PASS THIS POINT"; Victorian Railways locomotives were used to deliver wagons up to that point, where the engine would be uncoupled and any further shunting performed either with animals or machines with suitable safety devices fitted. In later years, safety wagons were provided to allow the locomotive to perform limited shunting without actually travelling beyond the limit.
Externally the wagon was largely identical to the grain wagons, but painted brown, coded FH1 and marked for superphosphate traffic. In May of the following year a further five wagons were converted to match. They were used for traffic between Corio and Wodonga until the early 1990s.
Like G1 before them, the original GH fleet were fitted with four hatches - two per side, between the axles and either side of the brake gear along the centre of the underframe. This made access to the brakes unwieldy, and the four hatches released grain too quickly for the conveyor belt systems. To resolve both issues later wagons were built with only two hatches, centered one either side which halved the grain delivery rate and made access to the brake rigging much easier. GH150 and GH151 were constructed with alternative braking arrangements, by cutting a small enclave in underneath one end of the hopper and placing the brake equipment there. Some further wagons were modified, but many (including some then under construction) only had the cut-out section constructed without shifting the brake equipment.
The addition of the roof section permitted a higher payload of grain, but between that and the weight of the roof, hopper sheets and hatch mechanisms, a GH wagon was significantly heavier than a standard tarped GY wagon. This led to problems with brakes, as the original braking systems for the lighter vehicles were retained. Further, wagons developed cracks in the frames not long after entering service, in the corners above the axlebox spring supports.
Safety wagons were used to keep locomotives and other ignition sources away from fuels or powders that could be ignited, by stray sparks or static discharge. Initially any random assortment of vehicles was used, but later officially allocated safety wagons were earmarked for specific duties.
Generally speaking, N QR wagons were modified as required for use on maintenance trains. In more recent times, Puffing Billy has utilised former louvre and cattle vans as travelling equipment storage, and has also acquired a pair of ex-Tasmanian hopper wagons for use on ballast trains; these have been reclassed as N N N. Details are covered on the appropriate page.
In 1935, the VR started transporting bulk grain. To cater for that traffic, 200 standard I wagons were modified with grain-proof seals and were coded G.
Just like the broad-gauge railways, the narrow-gauge lines required open and flat wagons for general goods. Over two hundred N QR wagons were constructed between 1898 and 1914, and these were designed as open wagons with sides and ends removable for use as flat wagons if required. Notably, on the Colac to Crowes line in the 1920s, sets of three N QR wagons would be coupled to transport cut timber pilings of lengths between 75–78 feet.