Smarter Cambridge Transport

How much do you value your journey time?

If you currently drive into Cambridge, why would you support a congestion charge? Probably for one of two reasons: the journey time is sufficiently shortened to be worth paying for (like the M6 Toll); or you’re given an alternative that is better value than driving now.

Whether either (or both) reasons hold depends largely on how much value you attach to your time. Academic research into this is based on surveys in which people choose between travel options that are either faster but more expensive, or slower but cheaper. This informs the official figure used in the UK, currently £13/hour for commuting trips. (Other trip types have different values.)

That figure is just an average though: the value you put on your time is likely to be different. The less money you have, the less you are willing or able to spend to save time. For the very poorest, the trade-off might be with paying for food or heating.

So, how does this apply to a congestion charge? Imagine it costs £10 to drive into Cambridge at peak times, but your round-trip commute by car becomes 20 minutes quicker. Rationally, you would pay the charge if you value your time at £30/hour or more. Otherwise, you will be excluded or feel aggrieved if you do not have a better-value alternative.

Assuming you need a car anyway; that parking at work is free; and the petrol cost is £1.50. The cost to drive is £11.50/day. Now, imagine you can travel by bus for £5/day, but the return trip takes 30 minutes longer than driving. If other factors balance out, do you pay a £6.50 premium to save 30 minutes? Rationally, yes – if you value your time at £13/hour or more. So, about half of people with those two options will choose to drive, and half will take the bus.

What about people who don’t have that choice and value their time under £30/hour? The travel time saving is simply not enough to compensate for having to pay the congestion charge. That is why local authorities must provide good-value travel options for everyone before introducing a congestion charge.

This article was first published in the Cambridge Independent on 13 November 2019.

Edward Leigh

Edward Leigh is the leader of Smarter Cambridge Transport, chair and independent co-opted member of the Cambridgeshire Police and Crime Panel, chair of the South Petersfield Residents Association, business owner, consultant, and occasional blogger about making the world and Cambridge a better place to live.


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  • A Cambridge Stagecoach Dayrider ticket is £4.50, or £7.00 if you live a little bit further (e.g. Cambourne) – prices and maps on this page:

    There’s factors to consider as well as the journey time:
    * predictability – the variation in the times of the bus arriving and leaving against the time table
    * capacity – the assurance of getting a seat on the specific bus, on days with normal demand at peak times
    * reliability – the probability that a specific bus will actually arrive and provide service
    * coverage – whether the bus provides service at a time convenient to the users especially if they need to start work early or finish work late
    * environment – does the bus provide a clean pleasant environment at the right temperature

    I am fortunate to live near the Citi 4 route which provides a regular service Monday to Saturday. How does it rate on those measure above?
    * predictability – off peak runs fairly on time, at peak, can be 5 to 10 minutes late, worse if A428 is congested
    * capacity – off peak fine, at peak you might be unlucky 1 in 20 journeys
    * reliability – 1 in 14 journeys may suffer an unscheduled bus cancellation and thus a long delay in arriving
    * coverage – good for a normal working day, very poor on Sundays, relatively infrequent outside of core hours
    * environment – adequate in moderate weather, can be deeply unpleasant in the heat of summer or the depths of winter

    Faced with these factors, there are significant times when I happily drive to avoid the bus. Or, do something else entirely like go shopping to Peterborough on a Sunday.

  • It would be interesting to add to such a model the psychological effect of the sunk cost of car ownership. A car costs the driver in depreciation, road tax and insurance whether they drive it or not. As a non car-owner I am often struck by how keen friends and acquaintances are to offer me a lift over sometimes rather short distances. They are being nice to me, but I suspect they may subconsciously be motivated to get more “value” from their car.

    • Businesses work on the basis of cost per mile for a car.
      However, I think that’s wrong, and Mehmet is right to point out the psychology of already owning a car. A car costs you money every day to sit and slowly rot away, whether you use it or not. It’s likely to be at least £5, for depreciation, tax, insurance and servicing.
      The marginal cost of fuel and additional servicing and maintenance might only be another £0.20 per mile.
      So if you want someone to use the bus, you’re competing with a thing they have already paid for.