Platform Screen Doors

Platform Screen Doors (abbreviated as PSDs) are used at many rail stations in the WolvHaven server that seperate the platform from the train tracks. WolvHaven was the first minecraft server/project in the world to incorportate piston-based platform screen doors that slid horizontally in its railway systems; which were invented in early 2012.

Prior to the creation of piston-based PSDs, the tracks were instead seperated from the platform by a wall of glass, with openings in the walls to allow passengers to board or alight.

History

Despite the creation of Platform Screen Doors to make the system more realistic; similar to the Singapore Mass Rapid Transit system and stations on the London Underground Jubilee Line Extensions, the doors were there to prevent players from getting onto the tracks into the paths of oncoming trains, which would disrupt service as the server was not familiar with traincarts properties at the time. It would also help to prevent trespass, and ensure that the automatically operated lines remained in service more often.

Since 2014, with the implementation of player-collision train properties on traincarts systems in the server, the WolvHaven has introduced rail lines that would not include the technology as it was no longer essential to have the doors installed at all stations.

Door Types

Small Profile

Earlier PSD models in the WolvHaven server utilised the small profile doors. The right leaf of a door and left leaf of another would be controlled by a singular redstone column. The small profile doors would fit in the server's rail infrastructure; which was of smaller scale at the time.

The earliest form of the PSD would consist of only 3 doors to accomodate the server's then 10-minecart trains. As they were retrofitted into stations that previously had platform glass walls, the redstone for the PSDs had to be compact.

As a result, the layout would consist of two single-leaf doors; one on each end, with a single double-leaf door in the middle; similar to that of a deep-level london underground tube stock with single-leaf doors on the ends of the train cars

Small profile doors do not have the abilitiy for individual door control, as the leafs of two different doors were shared by a single redstone column.

Wide Profile

The first Wide Profile doors were seen in the 3rd iteration of the WolvHaven city world - New Haven. Door spacing between 2 seperate doors are increased by 2 more blocks to allow the fitting of a seperate redstone column. This meant that the doors could be seperately controlled without interfering other doors, and each door leaf would be controlled by its own redstone column. A gap spacing between the two columns was also needed as redstone columns could not be placed directly next to each other without interfering each other.

This however meant that the platform length would have to be longer for a set of 3 double-leafed doors, which was fitting for New Haven's standard 20-minecart trains.

Wide Profile doors have since become the standard on most WolvHaven City rail infrastructure, with the exception of Metro Line 8 (4th Haven) which still employs the small profile doors to squeeze in an additional door for the line's longer 30-minecart trains

Iron Doors

Iron door based PSDs were introduced in 2014 and are primarily used in the BERT (4th Haven) system. BERT's owner, Axton preferred the utilization of iron doors as they would have a narrower profile of 1 block thick as compared to piston-based PSDs which were 2 blocks thick. The iron doors would come with a custom resource pack to retexture them into a texture similar to the London Underground Jubilee Line Extension's platform edge doors.

The decision for the iron-based PSDs; along with Axton's then vision of form-follows-function type stations led to disagreement between SilverWolv and Axton; which led to the birth of the BERT system.

Control Circuits

The platform screen doors on the server utilize many different types of control circuits that controlled when the doors open and close. They are triggered mostly by detector rails in the station; which signal the doors to open.

Mk I Train-Presence Circuit (2012)

Referred to as 'Type 1' by SilverWolv back then in his PSD building tutorials, the original PSDs in the WolvHaven server came with Mark 1 circuits called train-presence. Back then, the server's rail infrastructure mostly comprised of 2 termini stations with single platforms on each end. As a result, the earliest circuit consisted of a detector rail at the end of the platform on the terminating side. The doors opened as long as the train was on the detector rail.

The concept was that the detector rail would only be triggered when the train was almost fully in the station platform, opening the door when the train was in position by the traincarts station sign; making it unaffected by player movement.

As it was a terminating platform, as soon as the train started moving off, the detector rail would be released; closing the doors before the train would be affected by player interferrence. This model worked well until there was a need for intermediate stations.

Mk II Delay-Based Circuit (2012)

In response to the need of a circuit that would work well in an intermediate station, the delay-based circuit was developed. A detector rail is placed at the approach of the station near the last minecart. There would be a delay as the train entered the station, made using many redstone repeaters before the doors are opened. Another delay made using redstone repeaters is triggered afterwards for the length which the train is stopped in the station before closing the doors.

Mk III Flip-Flop + Delay (2013)

The Flip-Flop variant circuits was introduced in 2013, and worked on the idea that a signal was needed to trigger a flip flop; opening the doors and another signal would trigger the flip flop again, hence, closing the doors. This was often paired with a delay created with repeaters. Early versions of the flip-flop based circuits took advantage of the then-new minecraft featrure of dispenser interactions.

Boat Type Flip Flop

Boat flip flops were the first to be used. These were simpler to construct as compared to the redstone-torch based flipflops. BERT would utilize redstone-torch based flipflops but these would often prove unreliable. Boat flip flops worked with a boat which would float upon the placement of water from a dispenser, lifting a wooden pressure plate, hence opening the PSDs. Triggering the flip flop again would remove the water, and the boat falls onto the wooden pressure plate and closes the doors.

Dispenser-Hopper Flip Flop

Having water near redstone was risky to the circuits and another flip flop design was utilized which involed dispensers and a hopper. The size of the flip flop was also much smaller compared to the boat type variant. This flip flop version is used in most WolvHaven Circuits today.

Mk IIIA Flip-Flop Train-Depart (2013)

Flip-Flop train-depart uses a signal that is triggered by a detector rail when the train departs to close the doors by activating the flip flop. Despite its benefits of a smaller footprint, these were plagued with reliability issues; often having an opposite operation problem where the doors closed when the train was in the station; and opened when it was not. This frequent issue prompted the introduction of a "PSD Reset Button" that was often located in the middle of the platform to reset the doors if it was in opposite operation. A fine for misuse of WH$300 was imposed for misuse of the reset button.

Mk IV Train-Presence Departure-Preemption (2014)

This circuit was born mainly due to the tight floor-space in terms of height and width on the Metro Line 2 (4th Haven)'s above ground station platforms. A lightweight solution was that a train would trigger a detector rail upon arrival and continue to sit on the detector, which opens the doors after a delay. A second detector rail would be triggered when the train departed, cutting off the signal to the doors, causing them to close.

It worked on the simple idea that the amount of time the train takes to enter the station is the same as the amount of time it takes to leave. Hence, by the time the train releases the second detector rail, whatever redstone current that was stored in the delay for arrival into the station would have been released.

It's lightweight design also meant that it was less prone to severe failures, and required less maintenance. Following the success of this version, it was retrofitted on Metro Line 1 (4th Haven), replacing the MKIII circuits that were installed.

Mk V Microbrain (2017)

The next major revolution in PSD circuitry would come with the introduction of the microbrain type circuits, invented by Cupochan. The microbrain instead used a single minecart with delays controlled by station signs. Upon a train entering the station, a minecart is spawned which is stopped by a station sign meant to represent the delay which the train takes to enter the station. Afterwards, the minecart is pushed onto a detector rail which triggers the doors to open, and is held there by another station sign to represent the delay which the train is stopped at the station. Afterwards, the minecart is moved and destroyed, causing the doors to close before the train departs.

The lightweight, simple, and relaible implementation which the microbrain circuits provided was so successful that Metro Line 1 (4th Haven) was retrofitted with them, replacing the Mk IV circuits.

CB1 Command-Block Based (2018)

Command block based PSDs are also present where command blocks replace the doors with air and back with the doors again. This was introduced by Starcubed and the doors are implemented on at Stadium and Waterloo stations of the WolvHaven Metro (4th Haven). The footprint of such doors is large as schematics of the doors being closed and open had to be stored above/under the platform for the command blocks to copy them from.