The determination of shoppers to drive to the Westgate Centre, despite the likelihood – no, advertised certainty – of a full car park there, comes close to paralysing Oxford at weekends and other busy times.

That urgent action is necessary to end this stupidity is evident to all save those best able to supply it, by which I mean the local authorities, leasehold owners the Westgate Oxford Alliance (of developers Landsec and the Crown Estate) and the police.

Well, it must of course be evident to them too. They just choose to do nothing to alleviate matters.

On two days between Christmas and New Year – with the seasonal sales in full swing – I stopped to study precisely what occurs at the car park entrance in Thames Street. My observation proved most instructive.

Each day I spent about 40 minutes eyeing the traffic: on Sunday between noon and 12.40pm, and the next day from 11.25am till 12.05pm, with a further brief look-in about half an hour later.

There were signs on display throughout these times saying the car park was full. This state of affairs had been spelled out, too, in a notice at the Seacourt Park and Ride, notwithstanding which cars from the west proceeded on the crawl into the city.

This long line of exhaust-belching vehicles is, in effect, the Westgate car park queue, as is the one heading from the south along Abingdon Road.

Road users not bound for Westgate must necessarily join these queues. Absurd, or what?

It is strange to think that the county council is preparing to lavish £9.1m on a scheme designed to cut congestion on Botley Road when its own inaction elsewhere is serving to aggravate this very problem.

During my first Sunday monitoring mission, I saw at once – as who can fail to do – what goes wrong at the car park entrance.

Quite simply, drivers ignore the ‘full’ signs, turn into the car park access road, and continue to do so until this fills up and further admissions are impossible.

When this happens, the last car in blocks the eastbound lane of Thames Street, thereby holding up through traffic. The pinch-point is this single lane. Why the road was constructed in this way I can’t imagine; there are two lanes in the opposite direction, with one dedicated to the car park traffic.

In the course of the 40 minutes I watched, the eastbound traffic stood completely motionless four or fives times, for periods of five minutes or more.

Present, and keeping a vague eye on what was happening, were three yellow-jacketed officials, who observably were mainly inside the car park. I watched three times as one or other of them had words with the driver of the principal blocking car – that is, the one at the rear of the queue. I guessed (I was out of earshot) they were being asked to move on. None did; they simply continued their wait.

During my observation on Monday, I saw only one such request, again not acted upon.

This time, I emailed a series of messages to myself, outlining the hold-ups as they happened. They read: “Stationary traffic 11.30. Two cars blocking, No movement till 11.37. 11.41 blocked again till 11.45. Blocked again 11.46-48. 11.55 blocked till 12.03.”

Then I went off to my bank, looking in again on the way back. I wrote: “Arrived back 12.27. Blocked solid and remained so till 12.34. Left for home.”

So what’s to be done?

First, one needs to ask why shoppers insist on driving to Westgate, to which the answer, of course, is that it’s highly convenient, especially if you are loading up with purchases.

It is also – and this is a crucial point – a cheap way of getting there. Parking charges significantly undercut what is charged elsewhere in the city. For two to three hours parking – a period that would probably suit most shoppers – it costs £5 compared with the other car parks’ £9.

It is also cheaper than Park and Ride when the bus fares are added in. In a sane world this service would be free.

But why do drivers head for a car park when told that it’s full? It’s because they know it won’t be full for long. Such is the turnaround on the 1,000 spaces, they will eventually get in.

So what’s to be done? Clearly an alteration in parking charges – whether up at Westgate or down elsewhere – would be a good idea. Occasional police presence at the Westgate entrance might prevent wilful obstruction of the highway.

One sensible move, given that Botley Road is the beginning of the car park queue, would be to allow through traffic to turn off from it at Frideswide Square, and travel up Castle Street and around the shopping centre on the road currently reserved – a rule strictly enforced – for buses and taxis.

This will not be liked by the bus and taxi operators, but it would show the county council is prepared to act over a problem that is becoming a disgrace to the city.