Under cold outside conditions, parked trains are heated and lighted partly or completely overnight for several reasons:

• in order to guarantee optimum comfort when service starts next morning.
• in order to ensure a comfortable working environment for cleaning personnel during the night
• in order to avoid damage to equipment due to freezing

In countries of Central and Northern Europe, overnight standstill consumes considerable amounts of energy.

Existing solutions to reduce this energy consumption include:

• Manual control: Comfort functions are manually switched off after service and back on to “preheat” the coaches 1 or 2 hours before service starts. This is however expensive and difficult to organise.
• Automatic control: Comfort functions during standstill are controlled automatically by an on-board timer or (in a more advanced version) by telematics (remote control).
• Reduction of conversion losses: A special solution to this problem has been developed at DSB: A software tool allowing for the common energy supply of two trains via one pantograph. For details, see Coupling of parked trains for common energy supply
• Gradual heating during service: Some experts propose unconventional measures to save overnight heating. On those lines not requiring the full train capacity on the first track section (i.e. between the first two or three stations), it could be sufficient to heat only one coach overnight, and heat the other ones by recovered braking energy on the first track sections. This would however require not opening some coaches to passengers before the second or third station. Such an approach is expected to find no acceptance in railways and is therefore not promising.

This evaluation focuses on automatic control systems.

Technical details

No general system specifications for an automatic control of overnight operation of comfort functions in trains can be given since on-board control of comfort functions is highly heterogeneous. Existing solutions mainly differ with respect to the following features:

• Centralised control device for the entire train
• Possibility to operate lighting and heating at one third or half intensity
• Special programmes for anti-freezing or preheating operation

This heterogeneity of operation concepts makes any standard solution difficult.

Organisation

The coaches have to be warm when the trains are cleaned. However the time the cleaning personnel arrives varies too much to program the timer in a way to take this into consideration. Due to low salaries, the motivation of cleaning personnel to collaborate in such measures is generally low.

Heterogeneity of stock and stand-still facilities

The on-board equipment for controlling comfort functions are highly variable between vehicles. This impedes the development of a generalized automatic control with big scale effects.

Acceptance by management

As long as no metering equipment is in place to measure energy consumption during standstill, it is difficult to make a cost-benefit analysis and to convince management.

Danger of freezing

Some operators are reluctant to switch off heating in the night due to the danger of freezing and damage to equipment. DSB has discussed installing a timer to reduce the coach temperature to 5°C during the night and then automatically raise it to 22°C before service. However, it could not be ruled out that in exceptionally cold periods the inside temperature would fall below 5°C with consequences such as water freezing in the toilets etc. Therefore the measure was not implemented in the end.

• Assessment of current operation practice for standstill in order to identify possible measures and required functionalities of an automatic control tool.
• Motivation and incentives of cleaning personnel to collaborate in saving measures
• Advanced control systems to avoid danger of freezing etc.

PLC system at SJ

An automatic control for overnight standstill is currently studied in Sweden. The so called PLC system (Programmable Logistic Control) will optimise the use of electricity so that heat and light is minimised during parking hours, but automatically switched back on well before service starts again. During service the temperature lies between 18 and 20° C. When service ends, coach temperature is lowered to 12° C, and raised again to service temperature one hour before service start. This is done fully automatically. In order to avoid failures everything is built in twice.