21 Feb 2010

Will logic dictate?

I’ve been reflecting on my driving habits and looking to see how I can help myself and the environment. And of course ah trying tuh show Jumbie a li’le t’ing about scientific/mathematical analysis. :) ;)

I travel about 500 miles per week in a car sometimes, but on average 180 miles.

On many a morning I have 60 mile journey which takes me roughly an hour (60 mins). The return journey is about the same. Part of the journey is speed limited to 50 mph (in a 70 mph zone) due to road works – they’re widening part of the M25. [The M25 is probably one of the worlds biggest roundabouts – it circles London]. I’ve noticed that on the zones that are not limited I often try to catch up by going 75 mph or briefly over. Well lots of others do the same, some doing easily 100mph – not me, of course.

So, I’ve been thinking about the cost of my driving habits. I’ve noticed that even if I push it on the motorways I cannot (with the road works limitations) exceed an average of 60 mph. But I’ve been thinking about the cost of going faster in the areas outside of the road works.

Here’s some of the math based on ideal speeds, for the sake of analysis, over a 60 mile outward part of the journey.


Speed (mph)

Time (min)

Mileage (mpg)

Cost (£)

(petrol costs £5.00/g)











What the above suggests is that a time-saving of roughly 15 min would cost approx £2.60 for easy figures. Now here’s the thing – that’s £5.20/day (return) or probably £15.60/week and probably £624 per year (40 of 52 weeks) – at conservative estimates!! At an even more conservative estimate I could surely save £500/yr – just for easy and surer figures – if I drive slower.

However, the cost in terms of time of driving slower adds up i.e. 30 min per day extra on 3 days per week, for 40 weeks comes up to 60 hours in a year! That equates to 500/60 or £8.33/ hr. Well that ain’t bad for a tax-free saving.

The extra 60 hours on the roads comes with some benefits:

  1. More relaxed i.e. less adrenalin and less stress, so lower blood pressure.
  2. Less wear and tear on my car means longer life of engine, and better wear on tyres.
  3. Less greenhouse gases.
  4. Less risk of accident and injury (higher speed correlates well with the latter two).
  5. More time to think, plan, or take in more audiobook or Radio4 discussions.

The downside, if it is that:

  1. Getting up earlier.
  2. Extra effort to become more organised.
  3. Increased time exposure to static risk of actually being on the roads.

Overall there seems to be more benefits – tangible and not-so-tangible – to do all that allows me to drive at 55-60mph over the long distances. I’m coming to a conclusion that I need to do battle with my love of speed – ah mean one ah my machines can do 140 mph without a sweat (never done it doh). Logic dictates I should drive slower all round. Ah now have a problem – will I allow logic to dictate my actions?