By Anthony Reuben
Business reporter, BBC News
Have you been cutting back on the amount you spend on transport? Some people have.
There is a very close relationship between use of transport and the state of the economy, according to Stephen Glaister, professor of transport and infrastructure from Imperial College.
He says that he was involved with London government before there were reliable figures for the levels of employment in the capital.
"The best indicator of the level of economic activity used to be the traffic figures for the Tube and commuter railway lines," he says.
One of the hardest hit forms of transport so far has been air transport.
BAA, which operates airports at Heathrow, Gatwick, Stansted, Glasgow, Edinburgh, Aberdeen and Southampton, has reported falling figures for both passengers and freight.
Passenger numbers were down by 6.9% in December, compared with December 2007, while the fall in freight was even more severe, with the amount of cargo carried falling 15.1% last month.
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December's figure was actually a smaller fall than November's, which BAA says is "almost certainly attributable to the strength of demand for Christmas-period travel".
But it confirmed that many airlines had trimmed their services in line with weakening demand.
Such recent data is not available for the use of rail services, with the newest figures coming from the three months to the end of September 2008.
Total passenger kilometres from July to September 2008 up 3.5% on same period of 2007
Source: Office of Rail Regulation
In that period, the total number of passenger kilometres travelled rose to 12.8 billion, up 3.5% from the same period of 2007.
"Disruption causes a lot of long-distance travel," says Dr Tony Fowkes from the Institute for Transport Studies at University of Leeds.
His sources tell him that businesspeople travelling for crunch talks with bankers and lawyers, as well as people looking for new jobs, provide a boost to the figures in the early stages of a recession, before the use of trains begins to fall.
"Recessions tend to depress the number of rail journeys taken, but we haven't seen that yet," agrees John Dennis from the Association of Train Operating Companies.
Taxis and buses
Most information on the use of taxis and minicabs comes from anecdotal evidence rather than nationwide figures.
Radio Taxis, a company specialising in business contracts, ties the slowdown in its business to specific events in the credit crunch.
The company says its business went down by about 15% when Bear Stearns was sold to JP Morgan, 20% when Lehman Brothers went out of business and 30% when the banks had to be refinanced.
Severn Bridge crossings down 7.5% in November compared with November 2007
Source: Severn River Crossing
That 30% contraction is in line with what many cab firms around the country say they are experiencing.
The use of buses and light rail in Britain between July and September 2008 was up 4.6% from the same period of 2007, according to the Department for Transport.
But that figure is somewhat skewed by the new rules allowing free bus travel to those over 60 anywhere in England.
Bus use was up only 0.8% compared with the previous three months.
It is difficult to distinguish the trends in car and motorcycle use prompted by the downturn from those caused by the extreme movements in fuel prices over the past year.
Consumption of petroleum products for transport use fell 8.6% between July and September 2008, compared with the same quarter of 2007, according to the latest figures from the Department of Energy and Climate Change.
Prof Glaister says that traffic usually declines in a downturn and that the government's forecasts for congestion do indeed predict a dip.
The number of vehicles paying to cross the Severn Bridge fell each month from June to November 2008, compared with the same period in 2007, with the 7.5% drop in November the most recent figure available.
In London, the number of vehicles paying the congestion charge also fell 7.5% in the last three months of 2008, compared with the same period a year earlier.
Use of the M6 Toll Road fell 11.5% in the last three months of 2008, compared with the same period of 2007.
So we have already seen reductions in the use of airports, taxis and toll roads.
Rail travel is expected to fall, but has not in the figures published so far, while there is not yet a clear picture of what is happening on the roads because of volatile petrol prices.
Bus travel is expected to have grown further when more recent figures become available.