Filtering – the “elephant in the room”

As a motorcyclist I benefit from the superior manoeuvrability of my bike and the ability to avoid being stuck in traffic for hours on end. I can perform a manoeuvre known as “filtering”, which is where I travel in between lines of queueing or slow-moving traffic. But when it comes to teaching people to ride, filtering is the “Elephant in the Room“. It is rarely discussed in detail, and learner riders are discouraged from filtering until they have passed their test and gained some experience. The reason for this is simple – filtering is very dangerous and the advice is therefore not to do it.

But that’s ignoring the Elephant in the room.

Filtering is what we do when we encounter queues, because we can. It’s not illegal and it’s one of the benefits of being on a bike. And if you’ve only done your CBT and commute on a 125, you’re going to filter anyway, right?

So isn’t it time we discussed how to filter safely in more detail?

I think so, so here’s my take on it.

First and foremost, safety is paramount and so filtering should only be considered when it is safe to do so and when there is likely to be a real benefit from it. It should not be a habit – every time you see a two or more lanes of queuing traffic requires a considered decision to filter or not – don’t automatically enter the ‘filtering lane’ between the queues or you’re likely to get yourself into bother.

For each situation:

  • Evaluate the risks – are you sure the traffic isn’t about to start moving again, leaving you stuck in the middle looking for an escape route?
  • Evaluate the benefit – can you really make sufficient additional progress over and above sitting more safely in the queue?
  • Have a clear goal in mind – can you safely get to the front, or to where you can safely re-join the traffic?

Only when you have weighed up the above should you begin filtering. Then, as you proceed along the ‘filtering lane’ between the rows of queuing cars:

  • Keep your speed low – you need to be able to stop in a short distance if something unexpected happens, like a passenger or driver deciding to get out of a car as you ride past (it happens, and they won’t expect you to be coming alongside!). As a guide, no more than 10mph faster than the traffic in the queue and no more than 30mph max – at which speed you should rejoin the normal traffic flow.
  • Keep scanning with your eyes – looking for clues as to what might happen, drivers starting to move off, or looking to change lanes, front wheels changing angle, gaps opening up inviting the lane-changers, gaps closing as drivers weave from side to side (I often see people steering with their knees whilst texting or reading the paper!)
  • Keep you options open – look for gaps opening where you can re-join the queue should the traffic begin moving freely again. Be flexible and be prepared to drop back into the queue when the situation changes
  • Don’t forget your mirrors – watch out for someone filtering faster than you, move over and let them past, they’ll help move the cars aside for you (assuming they don’t have an accident by going too quickly!)

Note that ‘filtering’ is different to ‘overtaking’. Filtering is between lanes of traffic, Overtaking is to the right or left of traffic (i.e. not in-between it).

When overtaking queues of traffic the additional risk is that the vehicle being overtaken may suddenly and without warning move into your path. It is not uncommon for drivers who have been sat in a queue to give up and perform a U-turn without first looking for anyone overtaking them (as they won’t be expecting it, given they are sat in a queue that’s not going anywhere!). So only overtake if you have a clear idea of where you will return to your normal riding position and keep your speed low so you can stop if necessary – and keep your eyes peeled for someone abandoning the queue or getting out of their vehicle to see what is causing the queue!

What the Highway Code says about filtering:

Rule 88:

Manoeuvring. You should be aware of what is behind and to the sides before manoeuvring. Look behind you; use mirrors if they are fitted. When in traffic queues look out for pedestrians crossing between vehicles and vehicles emerging from junctions or changing lanes. Position yourself so that drivers in front can see you in their mirrors. Additionally, when filtering in slow-moving traffic, take care and keep your speed low.

Remember: Observation – Signal – Manoeuvre.

Rule 167:

DO NOT overtake where you might come into conflict with other road users. For example

  • approaching or at a road junction on either side of the road
  • where the road narrows
  • when approaching a school crossing patrol
  • between the kerb and a bus or tram when it is at a stop
  • where traffic is queuing at junctions or road works
  • when you would force another road user to swerve or slow down
  • at a level crossing
  • when a road user is indicating right, even if you believe the signal should have been cancelled. Do not take a risk; wait for the signal to be cancelled
  • stay behind if you are following a cyclist approaching a roundabout or junction, and you intend to turn left
  • when a tram is standing at a kerbside tram stop and there is no clearly marked passing lane for other traffic.

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