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M25 J4 stub - why is this M25 not A21? - Pondlife

Heading northbound towards Bromley from the M25 J4, there is a short stub section of the M25 which runs for about one mile to a roundabout where it becomes the A21.

Does anyone know the reason for this, and why it's not just the A21 immediately after the junction? I can't see any benefit in such a short section of motorway, and having a tiny section of the M25 that's between two roundabouts and not part of the main ring is a bit confusing from a road naming perspecitive.

The only thing I can think of is that this M25 stub ends at the GLA boundary, where tha authority changes from Kent to the London Borough of Bromley.

M25 J4 stub - why is this M25 not A21? - Sofa Spud

If it's motorway, then motorway regulations apply. Otherwise you'd have cyclists, horse riders and farm tractors using it !

M25 J4 stub - why is this M25 not A21? - dan86

This section isn't to far from where I live and it's not that long a section it runs from hewets farm roundabout to the roundabout at junction 4 I get what the op is saying about it maybe confusing people but I think like what has been said its because motorway rules apply and it's so short wouldn't be worth making up a new motorway number for it.

M25 J4 stub - why is this M25 not A21? - gordonbennet

Can't recall the junction itself because i haven't been down that way for years, but i suspect its as Sofa Spud said, not so much for leaving the M25 but more for accessing it from the other direction (assuming that is possible), if it wasn't motorway classed from the roundabout you could end up with non motorway traffic starting on the road by mistake (blaming satnav as usual) and ending up stumped when the real M25 begins.

M25 J4 stub - why is this M25 not A21? - dan86

Yes GB it flows both ways to and from the junction

M25 J4 stub - why is this M25 not A21? - gordonbennet

Thanks Dan, makes perfect sense now why its been done like this.

M25 J4 stub - why is this M25 not A21? - Bolt

before the M25 the A224 polhill was the original A21 to Sevenoaks, I used to keep an eye on construction of it as I live not far from it and wasn't sure how they were going to make the A21 layout, imo they could have done it differently but I was told they couldn't get the farmland/woods to build as they wanted

so it was constructed as you see it...though its a dangerous stretch of road due to cars getting in the wrong lane for the A224 and A21 to Bromley as they overtake/undertake all over the place

M25 J4 stub - why is this M25 not A21? - gordonbennet

before the M25 the A224 polhill was the original A21 to Sevenoaks, I used to keep an eye on construction of it as I live not far from it and wasn't sure how they were going to make the A21 layout, imo they could have done it differently but I was told they couldn't get the farmland/woods to build as they wanted

so it was constructed as you see it...though its a dangerous stretch of road due to cars getting in the wrong lane for the A224 and A21 to Bromley as they overtake/undertake all over the place

Is that the section that climbs the steep hill just before the MOD place set back on the left, opposite side of the road was the cafe, both places i visited now and again in my previous work.

The whole M25/A21 junction was a mess from the word go, with no or at best very limited access from A21 onto or off M25 as i recall, i know i had to take some odd diversions to suit when if they'd put a proper junction in when the built the thing many surrounding roads would have been much relieved.

But then the powers that be have form for this, look at the absolute pigs ear of M1/M6/A14 junction, which now its all sorted still has no access from A14 to M1 south or M1 north to A14, but at least poor souls aren't being killed or maimed regularly as was the case when the junction going onto A14 from M6 especially was a single lane with traffic light control.

M25 J4 stub - why is this M25 not A21? - Bolt

Is that the section that climbs the steep hill just before the MOD place set back on the left

Yes its known for not slowing cars down as they ascend the hill, some call it anti gravity, but the garage has gone and is now a restaurant

Part of the road on the downward side suffered landslips which still show as it was badly repaired, and I think part reason why they didn't make a slip road to it from M25, its still dangerous around that area

M25 J4 stub - why is this M25 not A21? - Bolt

before the M25 the A224 polhill was the original A21 to Sevenoaks, I used to keep an eye on construction of it as I live not far from it and wasn't sure how they were going to make the A21 layout, imo they could have done it differently but I was told they couldn't get the farmland/woods to build as they wanted

so it was constructed as you see it...though its a dangerous stretch of road due to cars getting in the wrong lane for the A224 and A21 to Bromley as they overtake/undertake all over the place

Is that the section that climbs the steep hill just before the MOD place set back on the left, opposite side of the road was the cafe, both places i visited now and again in my previous work.

The whole M25/A21 junction was a mess from the word go, with no or at best very limited access from A21 onto or off M25 as i recall, i know i had to take some odd diversions to suit when if they'd put a proper junction in when the built the thing many surrounding roads would have been much relieved.

But then the powers that be have form for this, look at the absolute pigs ear of M1/M6/A14 junction, which now its all sorted still has no access from A14 to M1 south or M1 north to A14, but at least poor souls aren't being killed or maimed regularly as was the case when the junction going onto A14 from M6 especially was a single lane with traffic light control.

yes its the MOD road, there has always been confusion as to whether its the A224 or A21 and still is, I call it the A21 not A224 others the other way round daft really but never mind

M25 J4 stub - why is this M25 not A21? - Pondlife

Can't recall the junction itself because i haven't been down that way for years, but i suspect its as Sofa Spud said, not so much for leaving the M25 but more for accessing it from the other direction (assuming that is possible), if it wasn't motorway classed from the roundabout you could end up with non motorway traffic starting on the road by mistake (blaming satnav as usual) and ending up stumped when the real M25 begins.

If the small section wasn't motorway, then anyone getting as far as the rounbdabout above the M25 could just go around the roundabout and go back the way they came. But I can see the argument that some people might "accidentally" end up on the M25.

But if that's the reason, why not call it the A21(M), like the short A102(M) section between the A2 and the southern end of the blackwall tunnel?

M25 J4 stub - why is this M25 not A21? - Bolt

But if that's the reason, why not call it the A21(M), like the short A102(M) section between the A2 and the southern end of the blackwall tunnel?

it maybe because the locals get confused between A21 and A224 so adding more road names to the signs will make matters worse, no leave as is thank you, drivers get confused enough with the signs on the road let alone signposts

M25 J4 stub - why is this M25 not A21? - Andrew-T

If it's motorway, then motorway regulations apply. Otherwise you'd have cyclists, horse riders and farm tractors using it !

So you call it the A21(M) .... ?

M25 J4 stub - why is this M25 not A21? - dan86

That would make sense but as has been said further up people get confused enough on the hewets farm round about as it is

M25 J4 stub - why is this M25 not A21? - Glaikit Wee Scunner {P}

A21 (M) would be a legitimate name, just like the A1(M) etc.

M25 J4 stub - why is this M25 not A21? - Bolt

A21 (M) would be a legitimate name, just like the A1(M) etc.

there is no need to give it a name it already has one, its called the M25, it only goes to the M25 north or south or back to Hewitts roundabout, that is it full stop!

M25 J4 stub - why is this M25 not A21? - dan86

A21 (M) would be a legitimate name, just like the A1(M) etc.

there is no need to give it a name it already has one, its called the M25, it only goes to the M25 north or south or back to Hewitts roundabout, that is it full stop!

Another way to look at it is an extension of the slip road on and off of the M25 to the A21

M25 J4 stub - why is this M25 not A21? - Bolt

A21 (M) would be a legitimate name, just like the A1(M) etc.

there is no need to give it a name it already has one, its called the M25, it only goes to the M25 north or south or back to Hewitts roundabout, that is it full stop!

Another way to look at it is an extension of the slip road on and off of the M25 to the A21

If you follow the Old A21/now A224 past the MOD explosives research place to a mini roundabout, turning left takes you over the M25 towards Dunton Green, where most people I know thought the M25 slip road was going to be built and seemed the most logical place to put it.

I heard it was altered to polhill itself until the road subsided and it was altered yet again and was built as you know it now, but as I mentioned before anyone using that route should beware of the Hewitts roundabout as its lethal at times

sometimes its quicker going on to the M20/A20 to Bromley Orpington though it is further to go, the A224 Sevenoaks way does get chocka very often since they put in the lights by Homebase, they slow the whole road up all the way through

M25 J4 stub - why is this M25 not A21? - dan86

A21 (M) would be a legitimate name, just like the A1(M) etc.

there is no need to give it a name it already has one, its called the M25, it only goes to the M25 north or south or back to Hewitts roundabout, that is it full stop!

Another way to look at it is an extension of the slip road on and off of the M25 to the A21

If you follow the Old A21/now A224 past the MOD explosives research place to a mini roundabout, turning left takes you over the M25 towards Dunton Green, where most people I know thought the M25 slip road was going to be built and seemed the most logical place to put it.

I heard it was altered to polhill itself until the road subsided and it was altered yet again and was built as you know it now, but as I mentioned before anyone using that route should beware of the Hewitts roundabout as its lethal at times

sometimes its quicker going on to the M20/A20 to Bromley Orpington though it is further to go, the A224 Sevenoaks way does get chocka very often since they put in the lights by Homebase, they slow the whole road up all the way through

Very true going from crittals corner up towards orpington via sevenoaks way in rush hour can be a PITA and is much worse since the lights were altered.

We go via chiselhurst and down lesons hill if we're going that way.

M25 J4 stub - why is this M25 not A21? - Middleman

We go via chiselhurst and down lesons hill if we're going that way.

Then you get caught up in the traffic emerging from Cray Valley Road and (on the opposite side) the Nugent Retail Park (not to mention the new development on the corner of Cray Valley Road and Cray Avenue when it opens). Then there's the run up to Carlton Parade. The very idea of using the A224 rather than the A20/M25 is preposterous.

I don't know what the objection is to calling the said road (between the M25 "proper" and the Hewitt's roundabout) as the M25 is. It's less than a mile long and is really just an elongated slip road (albeit from both directions of the M25). It has to have Motorway ("M") classification because it provides access solely to and from the M25 proper. Non Motorway traffic has no business using it.

BTW, the "Explosives" establishment nearby is Fort Halsted.

Edited by Middleman on 26/06/2019 at 00:04

M25 J4 stub - why is this M25 not A21? - dan86

You are right the traffic in the area can be bad and no matter what route you take.

My usual route to the M25 is via 5 ways up the A20 joining at Swanly but then the dartford crossing can be bad so depending on destination I might take the blackwall tunnel it all depends on where and when I'm going somewhere.

M25 J4 stub - why is this M25 not A21? - Bolt

You are right the traffic in the area can be bad and no matter what route you take.

My usual route to the M25 is via 5 ways up the A20 joining at Swanly but then the dartford crossing can be bad so depending on destination I might take the blackwall tunnel it all depends on where and when I'm going somewhere.

I think its about time a new crossing was built, or traffic control was improved over/under the Thames (doubt now that would help) due to volume of traffic

when that comes to a standstill everyone tries to go through Orpington and what a joke that has now become, it used to be a quiet Town who no one knew, on occasions you cant move because of traffic and as mentioned the centre being nearly finished next to Honda is going to make it even worse!

They cannot make a duel carriageway all the way through A224 because of the railway bridge unless they make a relief road but that's too expensive

M25 J4 stub - why is this M25 not A21? - dan86

You are right the traffic in the area can be bad and no matter what route you take.

My usual route to the M25 is via 5 ways up the A20 joining at Swanly but then the dartford crossing can be bad so depending on destination I might take the blackwall tunnel it all depends on where and when I'm going somewhere.

I think its about time a new crossing was built, or traffic control was improved over/under the Thames (doubt now that would help) due to volume of traffic

when that comes to a standstill everyone tries to go through Orpington and what a joke that has now become, it used to be a quiet Town who no one knew, on occasions you cant move because of traffic and as mentioned the centre being nearly finished next to Honda is going to make it even worse!

They cannot make a duel carriageway all the way through A224 because of the railway bridge unless they make a relief road but that's too expensive

Something needs to be done. My wife works in the esso station long sevenoaks way and can take 45 minutes sometimes to do a 15-20 minute journey.

M25 J4 stub - why is this M25 not A21? - Bolt

You are right the traffic in the area can be bad and no matter what route you take.

My usual route to the M25 is via 5 ways up the A20 joining at Swanly but then the dartford crossing can be bad so depending on destination I might take the blackwall tunnel it all depends on where and when I'm going somewhere.

I think its about time a new crossing was built, or traffic control was improved over/under the Thames (doubt now that would help) due to volume of traffic

when that comes to a standstill everyone tries to go through Orpington and what a joke that has now become, it used to be a quiet Town who no one knew, on occasions you cant move because of traffic and as mentioned the centre being nearly finished next to Honda is going to make it even worse!

They cannot make a duel carriageway all the way through A224 because of the railway bridge unless they make a relief road but that's too expensive

Something needs to be done. My wife works in the esso station long sevenoaks way and can take 45 minutes sometimes to do a 15-20 minute journey.

Only thing they appear to be doing is coming up with ideas that help to make more congestion for longer.

so far nothing apart from Leeson's hill lights has made a very small difference to waiting times as the traffic going into Leeson's hill, Station road have there own lights but that only helps them rather than speed up straight through traffic.

they could make most of it duel carriageway as there is plenty of room apart from the bridge, but even that may be re`opened up a bit as the paths were widened years for pedestrians

M25 J4 stub - why is this M25 not A21? - Middleman

There is absolutely no chance of the Sevenoaks Way/Cray Avenue being made into a dual carriageway. There is far too much commerce along its length and, although the footpath is wide under the railway bridge, to widen the road there (and in other locations) would mean the virtual disappearance of the footpath. More than that, the footpath accomodates a cycle lane for much of its length. A far better diversionary route when the junction 4/3 (and usually beyond) stretch is congested is the A225 through Shoreham and Eynesford but even this is unsatisfactory as it is single carriageway and not particularly straight.

I think drivers caught in traffic around J4 would do better to simply sit it out. The A224 and A225 had enough congestion when the M25 was incomplete and traffic from Dartford to the A21 or M25 towards Clackets Lane had no choice.

M25 J4 stub - why is this M25 not A21? - dan86

They'll probably leave it to get worse so more people will consider public transport but the growing traffic shows theirs no appetite for people to want to use the current model of public transport if so many are using their personal motorvehicles .