‘How much extra carbon dioxide was emitted because of the cyclist?’ asks A-Level exam paper

Ricardo did a more thorough exercise in evaluating any increased emissions on introduction of 20mph speed limits. Their conclusion:

• 1. There is no direct relationship between fuel economy and posted speed limits – the impact of 20 mph speed limits depends on changing driver behaviour

• 2. Steady-speed results and “emissions factor” curves must be used with care

• 3. IF the reason to introduce 20 mph limits is to: • encourage more walking and cycling • encourage slower, smoother, more considerate driving THEN it seems likely that this should result in a reduction in carbon emissions and quite possibly NOx and PM

And the DoT concurred:

“In principle, driving more slowly (at a steady pace) will always save fuel and carbon dioxide emissions unless a quite unnecessarily low gear is being used. The underlying arguments are that moving a vehicle at a lower speed requires less power, and that avoiding unnecessary acceleration and braking saves energy.” Department for Transport 

Erm yes the amount would be affected as the cyclist is breathing out carbon dioxide but otherwise the emissions from the cars don't actually matter as cars give out way to much no mater how fast they travel unless there electric power that is

And there I was thinking that physics was a science of observation and fact. 

I also understand that observation and fact has shown that 'Vorsprung durch Technic' really means 'Technology will overcome the test'.

I rode down the huge traffic jam this morning - two miles of stationary traffic in two lanes, with just enough room between them for little me.  Curiously, I was the only bicycle and the only vehicle making any worthwhile progress.

Is this what science education has come to now?

In an effort to make it 'socially relevant' they end up just revealing their ignorance of politics and sociology?

Do they make any attempt to justify their assumption that the speed of cars is entirely independent of the distribution of transport modes? Or that the car driver's decision to drive that route, use that vehicle, or to undertake the journey at all, is independent of their expected journey time? Everything else is held constant? How realistic an assumption is that?

I'm glad we had proper O levels in my day, as I'd have lost marks by just writing 'oh, just piss off, you're fooling no-one ' as my answer.

Um, the curve on the graph is entirely wrong. It's well known that driving faster uses more fuel, not less!

The question also doesn't address the Co2 that goes into the rebuilding of roads that's required due to vehicle loadings...  I am thinking of repeated decelerations and accelerations of  100's of kgs

you also need to calculate the total life-cycle cost, not just of manufacture, but of disposal too. You also need to factor in the cost of road construction, as cyclists can use the same standard of road, but don't need to. You could easily use these calculations to justify better provision of segregated routes.

But I am interested, as they've actually put some effort into quantifying the question. I thought this video was a one-off: https://www.youtube.com/watch?v=eS5fQqnB24U  , as it suggests there is an environmental impact of queueing behind cars, but makes no effort to do the boring actual sums

At least with this you have a starting point and some of the core variables to consider. Obviously there are other questions - you regularly see huge queues of cars, without a cyclist in sight, so if you switched from bike to car you would be increasing the probability and impact of those jams.

You also need to consider the total impact of these incidents against the reduced impact of switching from cars to bikes -  yes, there may be the odd occasion where other road users increase their CO2 pollution, but what's the overall situation

I love these sort of questions ...

And of course this makes no mention of the fact that CO2 isn't even close to being the worst thing that comes out of a cars exhaust pipe.

Added to which, were they Volkswagen cars? If so, you can multiply that CO2 figure by a few......

Is the Carbon Dioxide figure the actual figure or the lies that are put out by the manufacturers and never challenged by Governments?

As the roads are narrow and rural, the top speed the cars may travel at may well reach 65KpH, however as the nature of these roads are invariably narrow and twisty, how often would the cars reach this speed and what is the effect of acceraltions and deceleration when aproaching other hazzards on the road such as bends, unsighted crests of hills and approaching traffic?  Edexcel please show your workings.

18kph! - is this road through a ploughed field?

Just typical of the nasty insidious anti-cycling propaganda and clearly designed to detract from the overwhelming benefits of cycling.

Judging by part ii) Edexcel are a bit sexist too

Or, cars release the same amount of CO2 during their manufacture as they do, on average, for a lifetime of use. In the situation described above, what additional CO2 is released over a cyclist whos bikes manufacture cost 0.02kg per km on average?

Was the cyclist wearing a helmet?

c. The CO2 emmissions quoted are for the fuel consumed by each vehicle. Factor in the CO2 generated by the car production and end of life recycling processes, also the CO2 associated with the recovery of crude oil, refining into road fuels and delivery to the petrol station forecourt.

What if there were 3 cyclists on the road that would mean 3 less cars = zero emmissions, in turn cancelling out the immisions of the 3 cars queing behind them? 

But YES, propaganda I agree

Propaganda, pure and simple.