General: Revision of Motorway Speed Limits and Rules

[chelle_belle]

Fully loaded lorry in lane one hits a slight hill his speed drops to say 45mph, lorry behind is unloaded and can do 56mph but cant use lane two,
You can see where i am going with this.

[christheancient]

Originally Posted by volvorocks

Its the stopping from those speeds that will be problematic

Spot on!

At 100mph...

Thinking Distance = 100ft
Braking Distance = 500ft
Overall Stopping Distance = 600 ft (approx the length of two football pitches)

At 70mph...

Thinking Distance = 70ft
Braking Distance = 245ft
Overall Stopping Distance = 315 ft (approx the length of one football pitch)

For that extra 30mph, the overall stopping distance is nearly doubled!

And that is if the brakes are in good nick, the driver is alert and the road is nice and dry with a good surface.

I know which I prefer!

[stephend]

And the energy that has to be dissipated in a crash goes as the square of speed: in fact, it doubles on going from 70 to 100 mph. So if you crash at 100 mph, it's a lot more serious than if you crash at 70 mph - which is bad enough already.

I used to think that 80 mph was more realistic than 70 mph, and ACPO seemed to agree. But with the price of petrol nowadays, I'm starting to think again.

[volvorocks]

Originally Posted by chelle_belle

Fully loaded lorry in lane one hits a slight hill his speed drops to say 45mph, lorry behind is unloaded and can do 56mph but cant use lane two,
You can see where i am going with this.

Hi Chelle Belle and Craig!

Do see your point.

Would it be too much to expect though to expect the faster lorry to simply follow at the reduced speed for a little while until the slower lorry is back to 56mph?

TBH I have not come across that many lorries doing 45mph on the mway as the majority of HGV nowadays can maintain 56mph ish up and down hills loaded or unloaded due to their powerful engines. Yes ok they may have to drop a cog or 2 (or 3)..!!

My scenario from the previous page thus applies in this instance!

[volvorocks]

Originally Posted by stephend

And the energy that has to be dissipated in a crash goes as the square of speed: in fact, it doubles on going from 70 to 100 mph. So if you crash at 100 mph, it's a lot more serious than if you crash at 70 mph - which is bad enough already.

I used to think that 80 mph was more realistic than 70 mph, and ACPO seemed to agree. But with the price of petrol nowadays, I'm starting to think again.

Good point Stephend

Although regards petrol use at 80mph you still have the choice to do 70.
80 would be a limit not a target..LOL

Regards

[DesertDog]

People seem to think that the speed limit is the MINIMUM speed they should drive at....

[JamesV70R]

Originally Posted by adieu

But if the trucks keep a SAFE distance between themselves you'd have plenty of room. Vans should be able to travel as fast as cars on motorways, but keep the present 60 mph and 50mph limits.

Ducks behind sofa.

Originally Posted by volvorocks

Hi Chelle Belle and Craig!

Do see your point.

Would it be too much to expect though to expect the faster lorry to simply follow at the reduced speed for a little while until the slower lorry is back to 56mph?

TBH I have not come across that many lorries doing 45mph on the mway as the majority of HGV nowadays can maintain 56mph ish up and down hills loaded or unloaded due to their powerful engines. Yes ok they may have to drop a cog or 2 (or 3)..!!

My scenario from the previous page thus applies in this instance!

A lot of lorries, (although the MAXIMUM speed they are limited to is 56mph) are actually doing LES than that. Drop in behind a Tesco/Sainsburys truck and you'll likely find they are doing 53/54 for "fuel saving"

You say you think its not that bad to sit behind a slower lorry - if it wasn't that bad why do the ones that can do 0.5mph faster attempt the overtake in the first place? Because they CAN! Because they have deadlines to meet.

If its not that bad, why do *you* overtake anyone on the motorway? To get where you are going a few minutes (tops) quicker? Heres an experiment for you: Join the motorway, and stay a safe distance behind the HGV infront of you. Don't overtake, stay there.

You also mention lorries and safe distances ... How often do you see them driving so close together you couldn't fit your car between them if you tried? (These are the "bad eggs" I'm talking about here - the majority are pretty good)

[adieu]

245 ft wow....

VEHICLE TYPE: front-engine, rear-wheel-drive, 4-passenger, 2-door coupe

PRICE AS TESTED: $49,925 (base price: $38,990)

ENGINE TYPE: DOHC 24-valve V-6, aluminum block and heads, direct fuel injection

Displacement: 217 cu in, 3564 cc Power (SAE net): 304 bhp @ 6400 rpm Torque (SAE net): 273 lb-ft @ 5200 rpm

TRANSMISSION: 6-speed automatic with manumatic shifting

DIMENSIONS: Wheelbase: 113.4 in Length: 188.5 in Width: 74.1 in Height: 56.0 in Curb weight: 4093 lbs Braking, 70–0 mph: 156 ft

It's the last bit.... 156 ft
And its a yank tank.

[Daim]

Okay, higher speeds seem "scary" for some of you (by reading some of the posts here I got that impression) but have any of you driven on German Autobahns for a while exceeding speeds of 130 km/h (80 mph)?

The problem isn't your stopping distance, it is the other drivers. If the other driver won't expect someone to be driving 160 km/h (100 mph) and simply pulls out infront of you THEN you have the issue. BUT here in Germany people use their mirrors. They get the appropriate driving education needed...

Ever been overtaken by a car going 400(!) km/h (400 km/h = 248 mph!!!)? No? What do you do? You keep your eyes on your driver's side mirror and as soon as you think you are able to overtake, you look into it a few times! Not only once! And then you are on the safe side...

An increase in speed will require MAJOR education of the masses!

[volvorocks]

Originally Posted by Villan

A lot of lorries, (although the MAXIMUM speed they are limited to is 56mph) are actually doing LES than that. Drop in behind a Tesco/Sainsburys truck and you'll likely find they are doing 53/54 for "fuel saving"

You say you think its not that bad to sit behind a slower lorry - if it wasn't that bad why do the ones that can do 0.5mph faster attempt the overtake in the first place? Because they CAN! Because they have deadlines to meet.

(1)If its not that bad, why do *you* overtake anyone on the motorway? To get where you are going a few minutes (tops) quicker? Heres an experiment for you: (2)Join the motorway, and stay a safe distance behind the HGV infront of you. Don't overtake, stay there.

You also mention lorries and safe distances ... (3)How often do you see them driving so close together you couldn't fit your car between them if you tried? (These are the "bad eggs" I'm talking about here - the majority are pretty good)

Have highlighted the bits above to answer

1. Because I can - in safety and without pulling out too suddenly and slowing others down (No brown underwear if I pull out in front of you)

2.From time to time I do this as I enjoy a slower more relaxed speed sometimes BUT 3 under applies

3.Inevitably I get a lorry tailgating me maybe him thinking why is a fast car in the "slow" lane and reducing my lorry speed to 55.8mph (cue the lorry pulling into lane 2 for a 6 mile overtake manoeuvre) - so I either speed up (which may make the lorry driver think Im being awkward) or slow down in order to let him pass - which means me coming off cruise which I do not really want to do although if I stay on cruise the 6 mile overtaking manoeuvre commences.

regards