The Port Authority of New York and New Jersey publish an annual Airport Trafic Report, a mine of information about its airports and their traffic.

One gem I noticed in the 2008 issue (published last May: the 2009 issue should be out soon) concerns inter-airport transfers.

Table 2.8.1, part of the Passenger Demographics section, shows the profile of departing passengers - including their trip origin.
17% of JFK's passengers and 17.4% of Newark's passengers said that this was "another airport".

The survey was done in the terminals, but it isn't clear whether it was landside or airside. I'm trying to find out - does anyone out there know?

If it was airside, then these passengers could be in transit. They could have started their journey at London Heathrow airport, and were caught by survey staff as they passed through Kennedy or Newark Airports where they were catching flights on to domestic US destinations.

If however it was landside, then it implies that about one in six of the passengers departing those two airports had arrived at another New York airport and made a surface connection.

This, of course, isn't impossible - it's just time-consuming and not particularly easy, especially if you don't like cabs!

So it's curious that so many people appeared willing to do it - and, presumably, for them it was the best way to make the trip they were making.

In 2008, JFK saw 48 million passengers and Newark 35 million: 17% of these is about 8 million and 6 million.

Given the nature of the traffic at the major airports in the region, it is likely that a significant number of these passengers were transferring from LaGuardia airport. Supposing the number really is 8 million a year between JFK and LGA - that's around 30,000 a day or over 800/hour (assuming an 18 hour day). That's a lot of people!

People sometimes suggest to IARO that there should be inter-airport rail links - Heathrow to Gatwick is the favourite. But it's always felt that relatively few people actually make that kind of trip. People dislike journeys involving a change of terminal, leave alone a change of airport!

But recently a proposal has surfaced in China for a high speed rail link betwen the airports of Hong Kong (mainly served by international flights) and Shenzhen (mainly domestic flights). The concept is that people would fly into Shenzhen from mainland China, take the airside train for the 50km to Hong Kong Airport, then catch an international flight from there. A recent IARO report highlighted some of the difficult issues needing resolution for that system to work - and one of these was forecasting the size of the market (see the publications page of the IARO web-site.)

So it's interesting to see these figures from the other side of the world!

At the end of March, the UK Department for Transport issued its "Transport Carbon Reduction Delivery Plan".

A major problem I have with it is the downbeat attitude to freight transfer from road to more benign modes. This is typified by the use of statistics which, while no doubt true and accurate, are downright misleading. Moreover they've been known to be misleading since the mid 1970s.

The report, on page 64, says that, "68% of all road freight movements (measured by tonnes lifted) are within the same region and so are unlikely to have a viable mode shift option".

Let's set aside the fact that historically some of the heaviest freight flows in the country - by tonnes lifted - have been within the same region: these are flows of coal for power stations.

But let's look at two important factors.

First, we're talking carbon reduction. And that is a function, not of tonnes lifted, but of tonne-kilometers moved. 100 tonnes moved 20 kilometres use a lot less carbon than 100 tonnes moved 200 kilometres: you need the distance factor to measure the potential importance. Tonnes lifted is irrelevant.

Second, in 1974 a book called "Changing Directions" was published (and I remember, as a post-graduate student at Birmingham University, meeting some of the team who wrote it). This showed the the importance of distance very vividly on page 229.

The then Department of the Environment had calculated that the maximum amount likely to be transferred from road to other means was only 1.5%, based on the average length of haul of road freight travelling over 25 miles.

However, "Changing Directions" made the point that, if there was a mode transfer away from road of 60% of the road freight in the 150 miles and over range, 40% in the 100 - 149 mile range and 30% in the 50-99 mile range, the figure would be very different. About a quarter of all road tonne miles would be removed to other modes.

"Those who cannot remember the past are condemned to repeat it" (George Santayana).