Why do dual carriageways have 2 lanes?

mkirkby

Strider590 wrote: »

To be even more pedantic again

We all know (or I hope we do) that the highway codes states that the national speed limit on a dual carriageway is 60mph... UNLESS it has a central reservation, in which case the limit is 70mph.

Well yes because on a carriageway where we are not seperated from the oncoming traffic, it's safer to have a slower maximum speed. After all, we all know that a head on crash at a closing speed of 120mph is quite survivable, whereas if we are closing at a speed of 140mph, we must be protected :A

Never could figure out the logic of that speed limit rule

emmell

I was thinking the same as kwaks, maybe all the people in the left lane wanted to go left and didn't want to go flying down the right hand lane, to then have to get back into the left hand lane when the queue is bumper to bumper. That then causes congestion to people who want to turn right.
This happens where the M62 meets the M1 southbound, the inside lane is bumper to bumper, but if you want to turn off a few miles down the road it's very difficult to get back in. So it's safer to sit tight, after all, your not harming anyone who want's to try to progress a little quicker.
ML.

DaveF327

wealdroam wrote: »

What you have described is a single carriageway with wide white painted and hatched area.

Indeed. Look at a "carriageway" as being one uninterrupted width of tarmac from kerb to kerb. If there are two strips of tarmac separated by a physical barrier (usually having some form of kerbstones as its boundary) then you can class the pair as a dual carriageway.

To put it another way, if you can cross the entire road on rollerskates without going !!!! over tit, it's a single carriageway

emmell wrote: »

the inside lane is bumper to bumper, but if you want to turn off a few miles down the road it's very difficult to get back in. So it's safer to sit tight,

That can be quite true, which begs another question: Why can't the muppet at the front of that 10 mile queue put his foot down a bit so the traffic isn't bumper to bumper for miles? Discuss.


That was a joke, by the way...

goldspanners

flyingscotno1 wrote: »

Of course with nothing in sight at all, she joined and spent all of 1 second in lane 1 going straight from slip road to lane 2! :mad: I was amazed- why go to lane 2 when there is nothing else- it states on the signs on the road keep left unless overtaking. Muppet. I would have to go lane 1-3 then back to 1 to get past!

She was incredulous to it all and sat for 4 miles there passing nothing! Really wish the police had been there- people like that should be told to read the rules of the roads, it is so inconsiderate.

she should have been given 12 points, £20,000 fine and never allowed to drive again. folk like her that can't see any further than the end of thier nose should not be allowed to drive on any road.

shes the type of person that causes miles of congestion during the day on the M8.

Pew_Pew_Pew_Lasers!

Strider590 wrote: »

To be even more pedantic again

We all know (or I hope we do) that the highway codes states that the national speed limit on a dual carriageway is 60mph... UNLESS it has a central reservation, in which case the limit is 70mph.
So therefore, there must be dual carriageways somewhere with no central reservation :rotfl:

Im going to call my driveway a dual carriageway

To be even more pedantic, not all single carriageway roads are 60mph. One near me was, until only 2-3 years ago, 70mph. Single carriageway. And a single lane in each direction.

flyingscotno1

Pew_Pew_Pew_Lasers! wrote: »

To be even more pedantic, not all single carriageway roads are 60mph. One near me was, until only 2-3 years ago, 70mph. Single carriageway. And a single lane in each direction.

Only if it was under motorway regs with a number like A1234(M) then 70 is allowed with 1 lane in each direction. However that is technically a motorway not a single carriageway- you can't have an ordinary single carriageway A road at 70.

kriss_boy

jams on dual carriageways are normally because fools tailgait one another.

Pew_Pew_Pew_Lasers!

flyingscotno1 wrote: »

Only if it was under motorway regs with a number like A1234(M) then 70 is allowed with 1 lane in each direction. However that is technically a motorway not a single carriageway- you can't have an ordinary single carriageway A road at 70.

The two (motorway and SCL) are not mutually exclusive.