SPECIAL ROADS

2024-06-20

Sometimes I've seen signs on dual carriageways and motorways that seem to
specify a speed limit that's the same as the national speed limit (i.e. 60 or
70 mph for most vehicles, depending on the type of road), which seem a bit...
pointless? Today I learned why they're there, and figured I'd share with you!

To get there, we need a history lesson.

As early as the 1930s, it was becoming clear that Britain might one day need a
network of high-speed, motor-vehicle-only roads: motorways. The first
experimental part of this network would be the Preston By-pass (The Preston
By-pass lives on, broadly speaking, as the M6 junctions 29 through 32.).

Construction wouldn't actually begin until the 1950s, and it wasn't just the
Second World War that got in the way: there was a legislative challenge too.

When the Preston By-pass was first conceived, there was no legal recognition
for roads that restricted the types of traffic that were permitted to drive on
them. If a public highway were built, it would have to allow pedestrians,
cyclists, and equestrians, which would doubtless undermine the point of the
exercise! Before it could be built, the government needed to pass the Special
Roads Act 1949, which enabled the designation of public roads as "special
roads", to which entry could be limited to certain classes of vehicles
(There's little to stop a local authority using the powers of the Special
Roads Act and its successors to declare a special road accessible to some
strange and exotic permutation of vehicle classes if they really wanted: e.g.
a road could be designated for cyclists and horses but forbidden to motor
vehicles and pedestrians, for example! (I'm moderately confident this has
never happened.)).

If you don't check your sources carefully when you research the history of
special roads, you might be taken in by articles that state that special roads
are "now known as motorways", which isn't quite true. All motorways are
special roads, by definition, but not all special roads are motorways.

There's maybe a dozen or more non-motorway special roads, based on research by
Pathetic Motorways (whose site was amazingly informative on this entire
subject). They tend to be used in places where something is like a motorway,
but can't quite be a motorway. In Manchester, a couple of the A57(M)'s
sliproads have pedestrian crossings and so have to be designated special roads
rather than motorways, for example (There's a statutory instrument that makes
those Mancunian sliproads possible, if you're having trouble getting to sleep
on a night and need some incredibly dry reading.).

Now we know what special roads are, that we might find them all over the
place, and that they can superficially look like motorways, let's talk about
speed limits.

The Road Traffic Act 1934 introduced the concept of a 30mph "national speed
limit" in built-up areas, which is still in force today. But outside of urban
areas there was no speed limit. Perhaps there didn't need to be, while cars
were still relatively slow, but automobiles became increasingly powerful. The
fastest speed ever legally achieved on a British motorway came in 1964 during
a test by AC Cars, when driver Jack Sears reached 185mph.

In the late 1960s an experiment was run in setting a speed limit on motorways
of 70mph. Then the experiment was extended. Then the regulation was made
permanent.

There've been changes since then, e.g. to prohibit HGVs from going faster than
60mph, but fundamentally this is where Britain's national speed limit on
motorways comes from.

You've probably spotted the quirk already. When "special roads" were created,
they didn't have a speed limit. Some "special roads" were categorised as
"motorways", and "motorways" later had a speed limit imposed. But there are
still a few non-motorway "special roads"!

Putting a national speed limit sign on a special road would be meaningless,
because these roads have no centrally-legislated speed limit. So they need a
speed limit sign, even if that sign, confusingly, might specify a speed limit
that matches what you'd have expected on such a road (An interesting
side-effect of these roads might be that speed restrictions based on the class
of your vehicle and the type of road, e.g. 60mph for lorries on motorways,
might not be enforceable on special roads. If you wanna try driving your lorry
at 70mph on a motorway-like special road with "70" signs, though, you should
do your own research first; don't rely on some idiot from the Internet. I Am
Not A Lawyer etc. etc.). That's the (usual) reason why you sometimes see these
surprising signs.

As to why this kind of road are much more-common in Scotland and Wales than
they are anywhere else in the UK: that's a much deeper-dive that I'll leave as
an exercise for the reader.

LINKS

National speed limit

Special Roads Act 1949

Based on research by Pathetic Motorways

A statutory instrument that makes those Mancunian sliproads possible

Road Traffic Act 1934

During a test by AC Cars