50715 Air conditioning and heating concerns on 378 and 172 units
May 2012 in Train Operations
Concerns have been expressed about the lack of control that
Drivers have over the temperature within the cab on the Class 378
and 172 units. The air conditioning and heating systems in
these units are linked to a computer system. This creates
problems for Drivers if they are not comfortable with the driving
Class 378 units:
- The air conditioning system can only be turned off for 20
minutes at a time. This results in Drivers having to
repeatedly turn if off when it restarts automatically.
- When the heating is on in the cab, the air conditioning is also
on because it cannot be controlled independently. This can
result in the air conditioning creating a draft when trying to heat
the cab. If a Driver was to turn the air conditioning off, it
would also turn the heating off.
- The air conditioning is very noisy, and comes on straight away
when the cab is started up. However, it takes a while for the
computer system to boot up so Drivers cannot turn it off
immediately. The reporter states that the noise of the air
conditioning can often make it difficult for Drivers to hear
information over the radio.
Class 172 units:
- Drivers are able to stop the air conditioning for 60 seconds by
using the 'damper' button which is independent of the system, but
the reporter feels that this can be very distracting for
- The air conditioning in the Driver's cab is linked to the
system in the carriages, so if the Driver changes the temperature
in the cab this also changes the temperature in the
carriages. This has previously caused complaints from
- As in the 378 units, the heating cannot be run without the air
conditioning being on at the same time.
The reporter is concerned that the issues raised
with the systems on these units could cause Drivers to become
distracted and affect their ability to hear communications over the
- Consider separating the air conditioning and heating on the
Class 378 and 172 units so they can be controlled independently by
- Allow Drivers to have full control over the system, so that
they can turn the system off and leave it off?
- State what regulations the current system adheres to?
Response from London
LOROL would like to thank the reporter for
Heating Ventilation and Air Conditioning (HVAC)
systems installed into rolling stock are governed by the
requirements set out byRailway Group StandardGM/RT2176 Issue 1,
'Air Quality and Lighting Environment For Train Crew Inside Railway
Vehicles'. LOROL can confirm that both the 378 and 172 fleets
comply with the requirements set out in the standard and are
considered a climate control system. Of particular interest,section
5.1sets out a mandatory requirement to have at least 60 cubic
meters fresh air delivered to the driving cab per hour.Section
5.2sets out the requirement for carbon monoxide levels to be kept
to 'as near as practicable to the normal outdoor ambient levels and
shall not exceed 0.01% (100 parts per million). This requires
minimal ingestion of fumes and smoke generated by the train into
the areas where Train Crew carry out their duties'.
In response to specific queries raised by
- LOROL notes that the reporter utilises the 20 minute 'turn off'
function which is labelled 'smoke mode' and is a product of
complying with the requirements set out byGM/RT2176 section 5.2.
However, the repeated use of the 'smoke mode' does not allow the
HVAC system to provide the required 60 cubic meters of fresh air
per hour thus increasing the probability that the Driver who
employs the repeated use of the smoke mode becoming drowsy -
assuming emergency ventilation (drop lights) are kept closed. It is
therefore a mandatory requirement to have the fans or the window
- Programmable logic controllers prevent the air conditioning
from being on at the same time as heating. The reporter is mistaken
on this point.
- As pointed out in point one above, the system is not designed
to be turned off as it is a mandatory requirement to the system
operative or the window open. In terms of noise, LOROL have
trialled a noise insulation modification on 378255 and it was
accepted as an improvement by the staff representatives.
- As with 378s, the damper button is provided with a view of
preventing smoke ingress to the cab, it also closes the saloon
dampers for the same period of time. For the avoidance of doubt,
the damper button is not provided to turn off the fans for Driver
- The only shared functionality between saloon and cab is the
damper switch. The saloon is independently controlled by a control
panel in each of the body end cupboards. The reporter is mistaken
as to the functionality of the system.
- As with 378s, programmable logic controllers prevent the air
conditioning from being on at the same time as heating.
In conclusion, LOROL are in the process of
addressing the noise issue which should then remove the practice of
drivers repeatedly pressing smoke mode on 378s. It is quite clear
that the HVAC system is designed to be compliant withGM/RT2176and
turning the system off is not an option under consideration.
Drivers currently have full control of the temperature and mode of
operation; independent control of the system is not required as
there is no evidence to suggest further control would be of benefit
in light of the incorrectly perceived mode of operation