Low Adhesion Flashcards
When can low adhesion occur?
Any time of year but prevalent in autumn
What can cause low adhesion?
Leaves
Damp conditions
Factories/industrial sites/coal dust
Sea salt
Light rain following dry periods
Vehicles at level crossings
What is wheel slip?
Where train wheels cannot grip when trying to start moving
What is wheel slide?
Where wheels lock up completely, preventing you from stopping
What is there an increased risk of with wheel slip/slide?
SPAD/station overrun/track circuit failures (due to contamination)
What type of trains have an increased risk of slip/slide and why?
Disc brake trains as there is no direct contact between the brake block and wheel to clear contaminants
When is official Network Rail leaf fall season?
1st October to 24th December
What do sandite applicators do?
Apply paste to the railhead at areas of known low adhesion
What is the purpose of railhead treatment circuits?
High pressure water blasted at railhead
What must your actions be if passing a railhead treatment train on opposite line?
Conduct additional running brake tests as the water could dampen contaminants on your line without fully clearing them.
If you experience low adhesion whilst driving, how can you inform your colleagues at depot?
During hand overs or on whiteboards
If you experience seriously poor low adhesion and want to let your colleagues know urgently, how would you do this?
Ask the conductor to call ahead
What should whiteboard entries include?
Exact location, conditions, time and remarks. Network Rail then provide feedback.
How regularly do MetDesk meet in the autumn?
2x per day
What is the purpose of MetDesk meetings?
Discuss railhead conditions across the network to form an adhesion warning that is published in notice cases.
How are MetDesk warnings categorised?
Good to very poor (colour coded)
Which notice case are MetDesk warnings posted in?
Late Notice Case
Which MetDesk warnings are the most severe?
Red and Black
What does a red MetDesk warning mean?
Poor adhesion and high risk. Low adhesion in most areas and deteriorating
What does a black MetDesk warning mean?
Very poor adhesion (very high risk). Low adhesion in all areas- extreme caution required
How long are MetDesk warnings effective for?
Until withdrawn or superseded.
What are your actions if there are no MetDesk warnings posted?
Remain vigilant and conduct extra running brake tests
Where can historic low adhesion areas be found?
Sectional Appendix or Permanent Notice Case
What questions can help you judge the conditions?
Are you the first train of the day over the route?
What class/unit are you driving?
Has the railhead treatment train passed over the route recently?
Has the line been closed for a period of time?
Are there long gaps between trains passing?
Weather conditions?
Railhead appearance- black/silver?
Time of day- dusk or dawn?
Passenger loadings/brake impact?
Whiteboard information?
Late Notice Case/MetDesk notices?
Other drivers’ reports/handovers?
How is contamination categorised?
Level 1- lots of silver
Level 2- some silver
Level 3- no silver
When you are aware of low adhesion conditions, what must you carry out?
Additional running brake tests
When must you carry out additional running brake tests?
When required but more than usual.
When should you not carry out additional running brake tests in leaf fall season?
When approaching cautionary signals
When does the automatic sander operate, if fitted?
When WSP activity is detected and the minimum brake step that applies sand is selected.
What type of sander does the 150/1 have?
Manual sander, no WSP- auto sand in emergency only
What type of sander does the 150/2 have?
Manual sander and WSP fitted- auto sand in emergency only
What type of sander does the 155 have?
Manual sander and no WSP- auto sand in emergency only
What type of sander does the 158 have?
Auto sand in minimum step 2 and WSP fitted
When can manual sand be applied on 158?
With power still on and in wheel slip when engine revolutions drop
What type of sander does the 170 have?
Auto sander in minimum step 2 and WSP fitted
When can manual sand be applied on the 170?
When engine reverts to idle during wheel slip
If you are using step 1 when stopping at a station on 170/158 for comfort, what must you bear in mind and be prepared to do?
Sand does not auto apply in step 1- must be prepared to apply step 2 to obtain sand if required.
How many sanders are there per vehicle, which vehicle and which wheel?
1 per vehicle- only on vehicle you are driving from and applied to third wheel from free end (first driven wheel)
What are your actions if you require sand but the sand button doesn’t illuminate?
Press anyway as bulb may be flat
Which classes of train automatically apply sand when taking power?
None of the classes automatically apply power when taking sand- must manually apply if required.
Where should you avoid applying sand?
Over points, switch diamonds or swing noses
What will happen if you apply sand whilst in a higher brake step?
Sand will apply longer if in a higher brake step
How should you usually try to prevent wheel slip from occurring when leaving a station?
Use lower power notches and build power more gradually than usual
If there is no WSP fitted and you can feel the train slipping when trying to take power, what are your actions?
Apply a lower power notch and apply sand
If WSP is fitted and you feel the train slipping when trying to take power, what are your actions?
Leave power notch where it is and allow train to regain rotation on its own - apply sand when engine revs drop/engine idles
What indications might you get of wheel slip?
Speedo may bounce as driven wheels rotate quicker than free wheels, gearbox lights, WSP light and sand button might illuminate
What causes wheel slide?
Reduced friction between wheels and railhead (wheels quickly slow and lock up without slowing train)
What indications may you get of wheel slide?
Speedo may drop to zero when in a full slide as all wheels are locked, gearbox lights, WSP light, sand light may illuminate, sensation of being pushed.
What are your actions if you experience wheel slide and have no WSP?
Immediately release brake and apply sand
What are your actions if you experience wheel slide and have WSP fitted?
Leave brake alone and allow WSP to regain rotation on its own- if rotation is not being regained, apply higher brake steps. If not going to stop, apply emergency brake.
How should you report low adhesion to the signaller?
TIGER- Track is Good Expected Reportable
What are ‘good’ railhead conditions?
Conditions are good and there is nothing to report
What are ‘Expected’ railhead conditions?
Conditions no worse than expected for the location, poor adhesion may be present but nothing to report
What are ‘Reportable’ railhead conditions?
Conditions that are worse than expected for the location- poor adhesion has come as a surprise and you needed to take action. Inform signaller immediately
If you are unsure whether conditions are expected or reportable, what should you do?
Report them anyway
When the signaller has received a report of reportable railhead adhesion, what might the signaller ask the following train to do?
Conduct a controlled test stop
If the signaller asks you to perform a controlled test stop, what must you do?
Brake the train normally for the environmental and railhead conditions at that location (do not brake how you would for reportable conditions)
After you have carried out a controlled test stop, what must you do?
Report your findings to the signaller and confirm if conditions are reportable
What must the signaller do if you confirm that conditions are reportable?
Arrange for upcoming signals to be cleared to prevent SPAD risk
If asked to perform a controlled test stop in a platform, buffer stop or at any other location, what must you confirm with the signaller before doing so?
That the location has been railhead treated. The signaller must ensure this is done before arranging a test stop at any location.
Can you enter service with empty or faulty sanders?
Yes unless you believe that you may have difficulty stopping
What time of year must WSP be working?
Leaf fall season.
