I need to get from A to B, how should I do it? My obvious considerations include cost, environmental impact and my non-working time.

There is parking at the destination and a nearby train station so I can choose between car and train.

Option 1 - car

Time

Google maps has plotted a pretty simple route that it thinks will take 31 minutes and is 11.1 miles long. I wont be travelling at peak times, so hopefully the estimate is reasonable. With time to get in and out of the car this will consume about 35 minutes of my day (each way), during which time I obviously can't be working.

Cost

At 11.1 miles and approximately 30mpg (which my new car seems to be managing), the fuel cost is approximately £2.

Environment

My car claims it outputs 124g/km of CO2. I suspect in the real world it's actually slightly higher, but I don't have any better number to use. So for 11.1 miles it will produce about 2.2kg of CO2.

Option 2 - train

Time

National Rail can offer me a fairly well timed train, although I do need to change once during the journey. The total travelling time is 38 minutes. During which I can probably squeeze 28 minutes of work in (ie excluding change over time and assuming I get a seat on both trains).

However the public transport option has an extra time cost - I must walk at both ends of the journey to reach the stations. The walking time for a single direction would total approximately 30 minutes.

So this option, while providing me some working time while travelling, actually still removes about 40 minutes from my working day.

Cost

The train cost for each direction is £6.25 (the return fair divided by two).

Environment

According to the train CO2 calculator at co2balance, my single train journey would produce 2kg of CO2. Although this appears to be to the nearest kg and when I ask it to calculate for a return journey the total is only 3kg, so I will use 1.5kg as a fairer number.

Conclusion

I was expecting to travel by train, however it turns out that travelling by car for the day would save me 10 minutes of working time and £8.50 of real cash. It would however cost the world an extra 1.4kg of CO2.

Going back to co2balance they have a number of projects you can put money towards in order to offset the CO2 you produce. The most expensive project they currently offer is £9.00 per tonne. So the "cost" (if I wanted to offset it with money) of my 1.4kg of CO2 is approximately 1p. Although co2balance appear to insist on a minimum payment of £2.50.

So if I offset the extra CO2 (at £2.50), using the car still saves me £6 of real money, 10 minutes of working time, any risk of getting hot/sweaty/rained-on and all the normal train hassles (changes, late, cancelled, etc)!

This is a fairly local journey so perhaps that's just not where trains excel!?