Kaitiaki

Vigilance Enhancement System

Principles of Operation

Manufactured by Solid State Equipment Ltd, Lower Hutt, NZ March 1996

Index

There are three parts to the system - vigilance enhancement, data logging and track warrant. All three are run together on a microprocessor unit that accepts information from a variety of inputs and controls a variety of output devices.

Vigilance enhancement is used as a safety device on a locomotive to ensure that the driver is always alert.

Data logging is useful to determine the effectiveness of the vigilance enhancement, and to analyse what happened if an accident or near accident occurs.

The track warrant system ensures that the driver cannot run on a particular section of track unless a warrant has been obtained.

2. Vigilance enhancement

The basic philosophy is that if the driver has not been active then he is given a simple puzzle to solve. If the puzzle is not solved then after a warning, the train is halted.

Driver activity is gauged by measuring the time interval between normal driver actions, like changing the direction lever, changing the notch, putting the brake on, blowing the horn.

The puzzle is trivial - when the unit turns a light on, the driver turns it off.

The Maori word 'kaitiaki' means guardian or caring, as the system is there to assist the driver to drive safely, as a friendly support in a non-intrusive way.

Vigilance enhancement is only necessary when the train is in motion. It starts when:

It stops when:

The vigilance is reset by normal driver actions. These are:

If the time interval since the last action exceeds certain limits, then a light is turned on. This can be extinguished by any driver action. If the driver fails to execute an action within a certain time, then a whistle is blown and the light is left on. If the driver fails to respond to the whistle within a certain time, the brakes are applied, stopping the train. After the train has stopped, the penalty brake release button must be pressed to reset the vigilance and allow the train to proceed.

There is provision for more complex variations on this basic operation.

2.1 Timers

There are four timers:

When a timer is used, its duration is randomly chosen within certain limits. There is:

This allows a great flexibility in choosing times. For example, to choose a time with no variation, the minimum, and the maxima at low and high speed need to be all set to the same value (Fig 1.a). To choose a random time between set limits at all speeds then the two maxima need to be equal, higher than the minimum value (Fig 1.b). To increase the maximum at high speeds, this value needs to be higher than the low speed maximum (Fig 1.c). The reverse can also be true (Fig 1.d). Another variation (Fig 1.e) allows the minimum to be chosen up to an intermediate speed, then a range of values at higher speeds. The step value has a minimum value of one second, but may be increased if required (Fig 1.f).

In a simple setup perhaps the four timers are chosen as in Fig 1.a. Or the before light timer may be set up say as in Fig 1.c to provide a more random time, with wider variations at higher speed. This unpredictability is expected to enhance the ability of the driver to remain vigilant.

Fig 1 - Examples of timer settings

2.2 Multiple lights and pushbuttons

To further enhance the vigilance, up to three lights and pushbuttons may be installed. When in forward one of the lights is chosen at random. When in reverse one light is consistently chosen. If a light is on (light on or whistle blowing) pushbuttons associated with the unlit lights will not reset the vigilance.

Before the light is on, any of the pushbuttons (or of course any of the other driver actions) will reset the vigilance.

2.3 Brakes

If the cylinder brake in on, then this action resets the vigilance and holds it reset until the brake is released. Thus the vigilance is not operating when this brake is on.
When the dynamic brake is changed significantly, this resets the vigilance.

2.4 Overspeed

If the locomotive speed exceeds an overspeed value, then the light flashes (or the lights flash in unison if there are two or three lights installed) at about 3 flashes a second. The vigilance system is set to the condition when the light is on, and the only way to reset the vigilance is to slow down below the overspeed value. Thus the driver has the light on time (timer 2), plus the whistle time (timer 3) to slow down, before the penalty brake is applied.

2.5 Trail locomotive

If two locomotives are used in one train, then the trailing one will not start its vigilance system because its direction lever will still be mechanically in neutral.

However the trail loco's overspeed function will work and its lights will flash if it exceeds its maximum speed. The lead loco's vigilance lights will flash, as this signal is train-lined.

Thus the driver must react to the lower of the two overspeed settings.

2.6 Penalty

If the before light timer is cancelled with any of the pushbuttons more than so many times in so many minutes then a penalty is incurred. The light or lights flash a double flash sequence, and pressing any pushbutton will not reset the vigilance. Any other action can be used, as normal.

2.7 Slow flashing

All vigilance lights flash twice slowly when the vigilance starts.

A single slow flash occurs when the vigilance stops. A triple slow flash occurs when the system recognises that the loco is in trail. A single flash occurs when it goes out of trail.

2.8 Cell call

When the penalty brake is applied a signal is sent via the cell call radio link to base station.

A cell call is also initiated if the brakes are applied in an "emergency" way. This is defined as the loco in motion and either the cylinder brake pressure above a trigger value, or the brake pipe pressure below a different trigger value.

3. Data logging

Actions are logged in the Kaitiaki's memory for later retrieval and analysis. Depending on the loco's use, seven to ten days of data can be held, with the newest information over-writing the oldest.

Data is retrieved by connecting a Psion handheld or a laptop computer. The Psion can transfer its data to a PC computer via a direct connection or via a modem.

3.1 Clock

Most logging is related to a real time clock, providing year to seconds information. This is displayed if the keypad/display track warrant unit is plugged in.

Logging is always using New Zealand Standard Time, while the display shows Daylight Saving Time in the summer, and Standard Time in the winter. There is an automatic transition between the two.

3.2 Vigilance actions

All actions used in the vigilance are logged. If the vigilance is active (or if the loco is in trail) then time is logged as well, to a resolution of a second.

3.3 Speed, brakes and fuel consumption logging

Every ten seconds while the vigilance is active (or the loco is in trail), the average speed over the last ten seconds is logged, together with fuel flows into the engine. These readings are synchronised to the clock, at 0, 10, 20, 30, 40, 50 seconds every minute.

Brakes are handled by logging only when there is a significant change. The brakes logged are:

3.4 Fast log

The average speed over the last second, and the cylinder, pipe and EOT brake pressures are measured every second. When the penalty brake is applied, or when an "emergency" brake is applied, ten minutes of this speed and brake data is logged. There are about nine minutes of record before the event, plus a minute after.

3.5 Operational data

Also logged:

3.6 Statistical data

Whenever the power is turned on, or when the data is erased or read, then statistics are saved. These are:

3.7 Commissioning and diagnostic logging

Also logged:

3.8 Track warrant logging

See paragraph 5. for a description.

4. Speed

Pulses are derived from a pulse generator attached to one of the loco's wheels. Because the wheels are subject to wear, and occasionally they are re-tyred, there is provision for speed calibration, using the rolling diameter of the wheel. The pulse generator provides an integer number of pulses per revolution.

An output is provided for the EOT brake head unit, which also provides a display of distance travelled, and the pulses per revolution provided can be set independently of the pulse generator's value.

A further output is provided to drive the loco's speedometer dial, with provision for calibration. Because the original pulses from the wheel may be syncopated because of generator eccentricity or wheel shimmy, filtering is provided to give a smooth and easily readable speedo reading.

5. Track warrant

The track warrant (tw) system requires a keypad/lcd unit to operate.

Various sections of track throughout New Zealand's rail system are subject to track warrants. A driver must not enter a section without a warrant, normally obtained by radio.

Wheel pulse counts, added to keyed in initial position information allows the kaitiaki to derive the loco's position along the track. If a warrant is required, then the details are entered via the keypad.

The Kaitiaki requires:

The Kaitiaki blows the whistle at the call train control location and also at the points 6 km and 3 km before the start location. It applies the penalty brake before the start location if the warrant has not been obtained. Of course obtaining the warrant and cancelling the sequence means that the driver can proceed unimpeded.

Two track warrants can be entered, the second becoming active on the expiry

Designed and manufactured by: Solid State Equipment Ltd, Lower Hutt, New Zealand

Email SSEL for further information