[dunkalunk]

There are other factors that you need to consider when increasing speed limits:
-The faster you go, the more fuel you consume to maintain that faster speed
-if 120km/h is the speed limit, wouldn't that encourage travellers to travel even greater speeds?
-How much would speed limit enforcement have to increase? Could OPP resources be used better elsewhere?
-The possibility of more fatal accidents.
-Is it safe for cars to be travelling at 140km/h around transport trucks that will likely be going much slower?

[Edit: Removed irrelevant discussion about mid pen highway]

 

[jks]

There are other factors that you need to consider when increasing speed limits:
-The faster you go, the more fuel you consume to maintain that faster speed
-if 120km/h is the speed limit, wouldn't that encourage travellers to travel even greater speeds?
-How much would speed limit enforcement have to increase? Could OPP resources be used better elsewhere?
-The possibility of more fatal accidents.
-Is it safe for cars to be travelling at 140km/h around transport trucks that will likely be going much slower?

All these point are valid.
However, I never understood the whole using more fuel issue. Yes, you will use more fuel, and pollute the atmosphere more, BUT, you will get where you're going faster. This means that you are using more fuel and polluting the atmosphere during a smaller increment of time. It practically balances out.

 

[urbanfan89]

No it doesn't. E = 1/2 m*v^2.

Notice how v is squared. Hence if you double your speed you quadruple, not double, the amount of energy consumed, and you consume double the amount of fuel for the whole journey.

 

[TKTKTK]

There are other factors that you need to consider when increasing speed limits:
-The faster you go, the more fuel you consume to maintain that faster speed

without specific numbers, it's hard to know for sure, but I'd be willing to wager that the numbers aren't THAT different with modern engine technology.

-if 120km/h is the speed limit, wouldn't that encourage travellers to travel even greater speeds?

It shouldn't...our speed limits were intended to reflect the 85th percentile, (the speed that the majority of drivers are already travelling) That's become perverted over time, and now we have limits are that are (in most cases) pretty arbitrary.

-How much would speed limit enforcement have to increase? Could OPP resources be used better elsewhere?

Is speed limit enforcement really a worthwhile use of our limited Police force's time? Is speeding really one of our society's biggest problems?

-The possibility of more fatal accidents.

Possibly, yes. But it's hard to say how many more.

-Is it safe for cars to be travelling at 140km/h around transport trucks that will likely be going much slower?

Transport Trucks shouldn't be in the left-lane anyway.

Back on topic:
I would love to see any new highway construction take a back seat to other infrastructure...

It does.

 

[TKTKTK]

No it doesn't. E = 1/2 m*v^2.

Notice how v is squared. Hence if you double your speed you quadruple, not double, the amount of energy consumed, and you consume double the amount of fuel for the whole journey.

Does that take engine gearing, and the ability to alter your engine's peak efficiency, into account?

 

[waterloowarrior]

without specific numbers, it's hard to know for sure, but I'd be willing to wager that the numbers aren't THAT different with modern engine technology.

.

increasing your speed from 100 km/h to 120 km/h increases your fuel consumption by about 20%
http://retail.petro-canada.ca/en/seasonalarticles/1687.aspx

 

[TKTKTK]

increasing your speed from 100 km/h to 120 km/h increases your fuel consumption by about 20%
http://retail.petro-canada.ca/en/seasonalarticles/1687.aspx

I'm familiar with the graph. What's always struck me about the 100 to 120km/hr 20% efficiency decrease is that it assumes the same gearing for both speeds.

I'm in 5th gear doing 100km/hr, but in 6th at 120km (and the engine is revving about 1,500 less) 6 speed gearboxes are standard on pretty much anything worth driving now.

 

[afransen]

without specific numbers, it's hard to know for sure, but I'd be willing to wager that the numbers aren't THAT different with modern engine technology.

Wind resistance becomes a factor at higher speeds. Resistance due to air increases in proportion to the cube of the relative speed. Good for windmills, bad for cars and planes.

Is speed limit enforcement really a worthwhile use of our limited Police force's time? Is speeding really one of our society's biggest problems?

Two words: photo radar. Have a sign a kilometer before warning that there is photo radar in place. The penalties will have to be strictly monetary as you can't prove the driver in order to assign demerit points.

 

[kEiThZ]

No it doesn't. E = 1/2 m*v^2.

Notice how v is squared. Hence if you double your speed you quadruple, not double, the amount of energy consumed, and you consume double the amount of fuel for the whole journey.

Although you are right that wind resistance is proportional to the square of the speed, that does not comes from quantum physics. It comes from Newtonian physics. See below.

Wind resistance becomes a factor at higher speeds. Resistance due to air increases in proportion to the cube of the relative speed. Good for windmills, bad for cars and planes.

Actually its in proportion to the square of the relative speed:

http://en.wikipedia.org/wiki/Drag_(physics)

And a lot of that can still be minimized by a lower drag coefficient and a smaller reference area.

Two words: photo radar. Have a sign a kilometer before warning that there is photo radar in place. The penalties will have to be strictly monetary as you can't prove the driver in order to assign demerit points.

Don't give the nanny state government any ideas. They might attempt to balance the budget using photo radar!

 

[urbanfan89]

Don't give the nanny state government any ideas. They might attempt to balance the budget using photo radar!

They *might attempt* to use photo radar as a cash cow?

 

[afransen]

If you get nailed by photo radar when you have been warned immediately prior, you deserve the fine. No sympathy here, and all the better that it would go toward the budget balance.

You're right that it's the square and not cube (misspoke). Nonetheless, it becomes a significant factor in overall energy consumption and fuel efficiency for vehicles travelling over 120 kph.

From the wikipedia article Automobile drag coefficient.

The drag coefficient is a common metric in automotive design, where designers strive to achieve a low coefficient. Minimizing drag is done to improve fuel efficiency at highway speeds, where aerodynamic effects represent a substantial fraction of the energy needed to keep the car moving. Indeed, aerodynamic drag increases as the square of speed. Aerodynamics are also of increasing concern to truck designers, where a lower drag coefficient translates directly into lower fuel costs.

About 60% of the power required to cruise at highway speeds is taken up overcoming air drag, and this increases very quickly at high speed. Therefore, a vehicle with substantially better aerodynamics will be much more fuel efficient.

 

[MisterF]

-if 120km/h is the speed limit, wouldn't that encourage travellers to travel even greater speeds?

People tend to drive as fast as it's comfortable to drive, or the speed that the road is designed for. This is why, traffic aside, most people drive faster on a suburban street than a downtown street with the same speed limit. Most freeways in Ontario are designed for 120. Plus the OPP rarely gives tickets to people driving slower than 130. I suspect that if speed limits go up but the OPP doesn't change their standard, the speed people drive wouldn't change much.

Our highways are designed for 120, the police enforce 120+, most people drive 120, and the speed limit is 100. One of these things is not like the other...

 

[afransen]

I wouldn't say most drive 120. A substantial number do not drive that fast, partially for fuel economy.

 

[lordmandeep]

True but you should not be driving in the inside lane then...


Really even on suburban roads people are starting to drive 10km below the speed limit...

 

[catcher_of_cats]

Mods, is it possible to move all of this highway speed vs fuel efficiency to its own thread and allow this one to go back to discussing the mid-peninsula highway?