Dealing with cars slowing down ahead of you on slip roads

[JMac]

Hi, I'm a relatively new driver looking for some advice from my superiors!

On two separate occassions in the last 2 months I've been driving up a slip road onto a dual-carriageway, where a car in front of me has slowed down right at the last second. On each occasion I was joining a road with a 50mph limit, and traffic was flowing freely although there were a fair amount of vehicles. In each situation I had checked the traffic on the road, indicated, picked my spot and matched my speed to allow me to pull in to the gap in the traffic. I can't say for sure how far behind the car ahead of me on the sliproad I was, but I tend to leave at least 2 seconds gap.

On the first situation, I pulled out into the flow of traffic and was accelerating up to the speed limit (50), and I noticed that the car in front of me was still in the slip road travelling more slowly. I caught up with him and he continued to pull out, causing me to take evasive action and move over into the other lane.

The second situation (happened this morning) had a similar build up but the driver suddenly came to a stop at the end of the slip road. My split-second decision was that I was travelling too fast to stop in time (just under the speed of the main traffic flow) to avoid running into him so I pulled out into my "slot" in the traffic flow and passed him as he was at a stop at the end of the sliproad.

I seem to remember that there was a medium sized truck ahead of us in the main traffic flow which might have made the driver ahead reluctant to pull out.

So my question is, what did I do wrong, did the other drivers do anything wrong, what would you guys have done in these situations and what's the best way to drive to avoid it happening again?

It seems tricky to balance the need to accelerate up to the speed of the traffic while leaving yourself enough time to brake if required.

[Kimosabe]

Hi. Here's what I think.

1: Always prepare for traffic in front of you to stop and/or give way at the end of a slip road, because they are give ways. It may seem strange to consider them as give ways because we're used to filtering into existing traffic and expecting it to create space for joining traffic, hence matching your speed to their's but they are not obliged to do so and often don't. As much as those drivers should have made a plan to move aside to assist slip road traffic to join, it's not always possible or selfishly not what another driver may want, so slip road traffic should be prepared to stop if that hasn't happened. Observe the speeds some people drive along slip roads under the expectation that everything on the motorway is just fine and that someone will create a space to join into, even though it may well not be the case. Matching speed is a part of safely using a slip road but without good all-round observation, it's not that safe. Prepare to stop while looking to go. Same mantra is often applied to roundabouts. Don't assume that you'll be welcomed onto a motorway by someone else who might have switched off during a long journey. Some drivers 'automatically' pull into Lane 2 before an entry slip. This isn't a good thing to do, as they haven't yet seen if there's anything on the slip to move aside for or not. Fair enough if they aren't blocking Lane 2 with their automatic 'i always do this' attitude but if it's without thought, they aren't driving, they're just pressing peddles and moving a wheel.

2. If there are marked areas with solid white lines and diagonal stripes(I think some refer to them as 'tiger tails') at the end of the slip road where it joins Lane 1, don't cross that area to avoid slowing traffic on a slip road unless it's for emergency avoidance eg.due to avoiding someone driving into the back of you on the slip but even then, if it's possible to use the hard shoulder, i'd probably plan for/go for that than turn into fast moving traffic who might not have seen this. If the diagonally striped area is surrounded with broken white lines, this means that it can be crossed but again, you need to be 100% certain there's nothing in Lane 1 that's going to plough into you or while avoiding you, someone else in Lane 2 if you do this. Practice using your mirrors and doing really good shoulder checks so that you know what's in Lane 1 when joining and what other people on the slip road are doing. You really have to occupy that space and own it confidently/ predictably, as it's entirely possible that the white van man behind will try their best to force you into joining Lane 1 just so you're out of their way. Not very sympathetic. Also check out how much more you can see in your mirrors from positioning to the right hand side of the slip road than to the left or even the centre of it.

3. Also look ahead at what the other motorway traffic is doing as you may well find yourself catching up a block of very messy drivers, all of whom are changing lanes, accelerating and decelerating to avoid the nonsense. If you're crossing the motorway over a bridge before joining it, use that opportunity to look both ways up and down the motorway so you'll know what you might expect to find when you get there. I sometimes find it better to hang well back after joining a motorway until such traffic has sorted itself out, than to become the rear car in a block of traffic. I sometimes play a little game when driving on motorways. Sometimes drivers herd together in blocks or groups, packs etc. They all want to do 70+mph but can't until the pack has settled down and found it's place. I try to stay well ahead of a pack behind and well behind the pack ahead because this gives me all the road space I need and lots more time to plan and move as needed. If my journey is going to take 90minutes, I'd rather it took 100minutes without hassle than 89minutes tangling with the varieties of abilities of other road users.

4. Leaving a motorway. Not all drivers are aware of their speed and the red lights at the top of a slip might not give them much of a clue, so watch your mirrors for them. I tend to do all my slowing down on the slip when possible as i'd rather spend as little time on a motorway as possible. I also reach a very slow speed way before the end of any queues, crawl up to them and carefully observe what's going on behind me to ensure others are doing the same. This buys me lots of room to give them the message that there's slow moving or stationary traffic ahead. I often stop short while preparing to move forward, if I think the traffic which may arrive behind me might not expect to find a queue of traffic due to it being stopped over a hill. Treat ups and downs as 'vertical bends'. Bit off the point but worth a mention.

Hope this helps.

[Matt62]

I tend to leave a really long gap between myself and the next vehicle on entry slip roads, and extend it even further if I think I have identified a potentially problematic driver in front (someone who is very slow off the mark at a preceding roundabout etc.). Although this possibly means temporarily annoying any following traffic, it then gives you a clear and fast run down the sliproad, using enough acceleration to lose/appease the following traffic.

[triquet]

I tend to leave a really long gap between myself and the next vehicle on entry slip roads, and extend it even further if I think I have identified a potentially problematic driver in front (someone who is very slow off the mark at a preceding roundabout etc.). Although this possibly means temporarily annoying any following traffic, it then gives you a clear and fast run down the sliproad, using enough acceleration to lose/appease the following traffic.

Yep, that's my tactic as well. It's particularly useful on the evil short slips onto the A34.

[JMac]

Yep, that's my tactic as well. It's particularly useful on the evil short slips onto the A34.

Funny you should mention the A34, both the incidents I mentioned were on the A34 near oxford! The first was coming on southbound at the peartree interchange, the second coming on northbound at the botley interchange.

Are these slip roads particularly short then compared to others?

[triquet]

Frankly yes.

[Silk]

Hi, I'm a relatively new driver looking for some advice from my superiors!

I'm sure one of those will be along shortly but, in the meantime, here's my view: -

The trick with slip roads, and pretty much everything else for that matter, is getting as much information as possible as early as possible. This means gauging the volume of traffic on the main carriageway, and spotting the potential gaps as early as possible. As has already been said, you must treat the merge line as the line where you must stop until such a time as you're sure it's safe to go - you should never rely on traffic on the carriageway letting you out. You want to have a clear run at the carriageway - this means if there is a vehicle ahead of you on the slip road, let it join first so you don't end up in the scenario described. Depending on view and density of traffic, you can always join straight into lane two and get ahead of the dawdler in front, but you have to be absolutely sure you're not going to end up in conflict with other road users before committing to this.

[TheInsanity1234]

The entire A34 is littered with a bunch of jokes of slip roads.

Most of the slip roads south of the M4 alongside Newbury are ridiculously short, and most of them are preceded by a sharp right-hand turn just before turning left to join the traffic. This means you often have very little visibility until you're alongside the traffic, by which point, there's no time to accelerate/brake!

[TripleS]

Hi, I'm a relatively new driver looking for some advice from my superiors!

I'm sure one of those will be along shortly but, in the meantime, here's my view: -

The trick with slip roads, and pretty much everything else for that matter, is getting as much information as possible as early as possible. This means gauging the volume of traffic on the main carriageway, and spotting the potential gaps as early as possible. As has already been said, you must treat the merge line as the line where you must stop until such a time as you're sure it's safe to go - you should never rely on traffic on the carriageway letting you out. You want to have a clear run at the carriageway - this means if there is a vehicle ahead of you on the slip road, let it join first so you don't end up in the scenario described. Depending on view and density of traffic, you can always join straight into lane two and get ahead of the dawdler in front, but you have to be absolutely sure you're not going to end up in conflict with other road users before committing to this.

I wouldn't disagree with any of that, but if you can recognise early on that you have a slow driver in front, I find it best to overtake them on the slip road (if it's long enough and the space is available) then you're in the driving seat, so to speak, and their dawdling is not going to affect you. You can then largely forget about them and concentrate on making your own safe entry onto the main carriageway and go on your merry way.

Apart from any uncertainties caused by slow drivers on the entry slip road, I've generally found life easier if you can be travelling more quickly than the traffic on the main carriageway and nip smartly into a suitable gap ahead of you, rather than waiting for the aforementioned suitable gap to catch up with you, if you see what I mean.

For example, coming off the M18 and joining the M1 to go south (M1, J32) the last bit of the M18 has a fast LH curve (90 mph is fine at this point) and this leads onto a very large radius RH curve on the M1 as you join it. A good head of steam at this point works wonders. It sometimes pays to be bold.

[Gareth]

For relatively short on-slips and those with limited vision onto the main carriageway, I find it useful to plan to stop at the earliest point you have suitable vision and are in a position to use maximum acceleration. Sometimes you won't need to completely stop.

[Mr Cholmondeley-Warner]

I think it's been said in one way or another by various posters but basically, if there's someone else on the slip road with you, you need to be either in front of them (if there's space to overtake them) or far enough behind them that you can do your own thing without them affecting you - so either, get past, or leave a BIG gap behind them.

[akirk]

I think it's been said in one way or another by various posters but basically, if there's someone else on the slip road with you, you need to be either in front of them (if there's space to overtake them) or far enough behind them that you can do your own thing without them affecting you - so either, get past, or leave a BIG gap behind them.

exactly...
or if both are difficult (no space to overtake / pressure from behind) just treat it like a country road where you can't overtake - reasonable distance behind - slow down, deal with joining the more major road - and then look to increase speed at a less hazardous moment - reality is it will make virtually no difference to your journey other than to make it more relaxed!

Alasdair

[Garrison]

I can't say for sure how far behind the car ahead of me on the sliproad I was, but I tend to leave at least 2 seconds gap.

Agreed with everything that has been said so far.

I would only add one perspective. As the end of the slip road is a give way in reality, and should be treated like a T-junction or joining a roadabout, the 2-second rule does not apply as you are no longer in a following situation. In fact, the gap could be treated as an "infinity" rule since if the car in front stops, you should never run into the back of it. Hence the time gap should be big enough to become infinity. You have to manage your position, speed and the traffic situation behind, with a planned escape route (for example, an emergency lane or a gap in the traffic).

[akirk]

in addition, when joining a slip road, you plan not just for your movement, but how it affects others already on the more major road, so with a car ahead you now need to ensure that your plan caters for you / that car / how you affect others on the major road / how anything you do affects the other can and therefore affects other on the major road... it gets very complex - holding back to bring it to a situation where their joining and your joining are two distinct events simplifies it considerably

Alasdair

[Kimosabe]

.....and then look to increase speed at a less hazardous moment - reality is it will make virtually no difference to your journey other than to make it more relaxed!

Alasdair

And there's the key for me, the purpose of the drive. If it's about time, sometimes A-B could take minutes longer, sometimes hey ho. IF you didn't get past that slow driver on the slip, when you did pass them, how much time did you lose vs how much are you now gaining? Generally the answer to both is 'not a lot', unless you have a very fast car and clear road ahead. I generally have neither.