solving cambridge congestion (and increasing inner-city trade)

Cambridge has a traffic problem. It’s not the worst in the country I’m sure, but it’s problematic enough that various expensive and almost certainly fatally flawed schemes have been proposed, and some even mostly built as a result.

Whilst something as drastic as a one-way inner ring road would certainly be bold, it’d also be expensive and the outcome might not be quite what was expected. One thing that hasn’t been done is try a very simple and fairly cheap experiment, which changes just one aspect of charging for parking: charge less the longer you stay.

All short stay parking in the UK that I’ve been in charges by a unit of time with increasing amounts for longer stays – a typical weekday tariff for Cambridge (Grafton East) currently is:

Up to 1 hour    £1.50
Up to 2 hours £3.00
Up to 3 hours £4.50
Up to 4 hours £7.50
Up to 5 hours £14.00
Over 5 hours £19.00

To balance this out, the Park & Ride service is a flat £2.20 per adult (up to 3 kids per adult free), so based purely on up-front cost a trip to town for a family of four is cheaper by bus if they expect to stay for more than 2 hours.

So what is the purpose of parking charges ? It’s too expensive for residents to use instead of on-street parking, and it’s also not cost-effective for general shop workers to use so it must be intended for visitors to the city.

So what are these parking charges actually doing ? They’re creating a high number of short visits by multiple people, thereby increasing the number of cars on the road. The people who do drive in are also conscious of the cost per hour, and so are unlikely to linger but rather go to the shops they know they want to visit and then leave.

Right – now invert the charging structure:

Up to 1 hour    £19.00
Up to 2 hours £14.00
Up to 3 hours £7.50
Up to 4 hours £4.50
Up to 5 hours £3.00
Over 5 hours £1.50

This has now given a huge incentive for shoppers to stay longer in the city, so coffee and food traders will see an increase in earnings. It encourages people to wander around the side streets and investigate small shops they might otherwise rush past, and supermarkets will tell you all about the money to be made from impulse purchases (look at the end-of-aisle promotions and stock next to the tills). Rather than rushing back to the car to get into a cheaper ticket rate, visitors would be encouraged to spend another 20 minutes instead.

It would also encourage shop workers to drive in – these people are essential to the centre of town as without them there would be no place for the money to be spent, so it makes no sense to exclude them, and yet given that living in Cambridge is so expensive most workers live outside and have to depend on public transport to get to work. There are many complaints about the lack of services at the times the workers need them, as there’s not the volume of people other than the workers wanting to catch the bus to make running early/late buses cost-effective.

But the most drastic effect would be on traffic volume – the morning and evening volume would be increased, but could easily be compensated for by having longer retail opening hours which would be made possible by the increased spend per person. Notice how in the current system a family needs to be in and out in 2 hours or less. Given a typical 9am to 5pm period of 8 hours that means that for each parking space there could be 4 cars in that time frame, but in the inverted model it would be likely just to be one car per space – 75% of the daytime traffic has been removed ! People just wanting to get one or two items would now be much better off using the Park & Ride, reducing congestion, increasing bus reliability and keeping the traffic on the surrounding dual carriageways and out-of-town car parks.

In order to ameliorate the morning and evening volumes, there would need to be encouragement given to retail outlets to open from 8am to 8pm and that specifically includes all food outlets. No-fee extensions to food/drink licences to match the new hours would be a good start, and other bureaucratic reductions should be enough to stimulate this move (eg: make business rates variable with opening hours, and make it cost more for retail premises to open from 9am to 5pm than from 8am to 8pm).

An 8am retail start would mean that shop workers would arrive before office workers, and with a 2pm shift change this should see a second traffic peak finish before the end of school traffic builds up. Having later opening in the evenings would make it far less important to get into the city at the weekend, and encourage families to meet up there, shop and eat into the early evening. Just as the idea of having a half-day on Wednesday and Saturday mornings has passed into the ‘quaint’ category, it’s time to question the sense of a single start and end time for everyone as it’s readily apparent that transport infrastructure can’t cope, but changing hours is far simpler than building roads.

Moving away from a single work day of 9am to 5pm and towards a split 8am-2pm/2pm-8pm working pattern would also make retail work more attractive for students able to fit in work around lectures as well as offering parents with families a chance to work around school hours without having to pay for expensive childcare or ask for special dispensation from business owners. This would then enable the start of a much bigger social change, and keep skilled and motivated employees able to work instead of being forced to choose between family or career.

It’s so simple and cheap (reprogram tickets machines in 6 or 7 car parks and reprint notice boards with new pricing for the same) that it could never possibly work, of course. Why ? The main looser is the council. Despite being a public body elected to serve the needs of residents and businesses the fact that the vast majority of the parking charges under this scheme would be very likely to fall into the £1.50 or £3.00 range would mean that it wouldn’t even be tabled as a serious motion. It’s a pity that the elected officials can’t see that some short term pain is required to actually create a solution rather than make it “Someone Else’s Problem”. I’d say it will cost more in real terms not to try this for 18 months and see what the results are: if it works well then the increased number of businesses in town generating income via rates should offset the parking losses.

(With many thanks to James for the retail hours/office hours split).


  1. andrew January 28, 2009

    Nice reasoning. One problem though: how do you stop the car parks filling up from town-centre office workers, leaving no space for shoppers. Perhaps you want a price function that dips then rises again?

    Ideally you want to make the pricing proportional to the traffic volumes at the time of entry/exit, so 9-5 is exhorbitant. But that wouldn’t fit easily on a display board.

  2. ian January 29, 2009

    Hi Andrew,

    Well initially I had in mind that the staff should be allowed to park all day, but I’m now wondering if that would cause an increase in staff car usage and fill all the spaces. Instead, I’m leaning towards the social change aspect of removing the ‘one working day’ idea and using existing legislation to help drive this.

    Apparently (as told to me by someone in retail: I must follow this up) if you work for no more than 4 hours then employers aren’t obliged to offer a lunch break, so instead of moving towards two large chunks of 8am to 2pm and 2pm to 8pm (loosely modeled after the current ‘working day’) get slightly more creative and have three shorter ‘days’ of 8am to 12pm, 12pm to 4pm and 4pm to 8pm. This has the advantage of reducing the costs to employers, and also enables workers with families to more easily fit around school times and so go back to work when they otherwise couldn’t (as childcare would cost more than their salary).

    So to bring that back to parking charges, the tariff and the Park and Ride need to be kept so that the typical one shift worker would be better off on the bus (as it is with the inversion, happily !). There’s no need to worry about anyone doing back-to-back shifts as I would expect them to be less common than single ones, and there’s also no need to be concerned about a worker staying in town after their shift and shopping until the charges drop again, as that’s exactly the point of the charges, and they are then contributing back to the shops in the centre. The Park & Ride agreement does need to have some legal work done by the council to ensure that it runs for a minimum of 40 minutes before the retail outlets open and an hour after they shut.

    To fill in another glaring hole, there also needs to be an 18 hour or 24 hour limit on a stay before a penalty is applied (perhaps £100 ?) to prevent residents from staying in a car park. Although for the record I think the way residents permits are issued in Cambridge is bordering on criminal, there’s simply not enough space to sort that mess out with car parks. It would also be helpful for hotels to be able to do something to allow very long stay parking for city visitors, as Cambridge is certainly the sort of place that you could drive into on a Friday evening, park until Sunday afternoon and walk to most places of interest. This is the kind of use that ought to be encouraged as being a great way of bringing money into the city, so maybe the hotel could sell a ticket that is accepted at the car park barrier and is tied to the number of nights the room is booked for at, say, £10 per day.

    Thanks for your comments,

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