That is not too far away from the projected toll for the Western Harbour Crossing at $30 a car when it is due to open in 1997.

Furthermore, extrapolating out the $28 figure, to 1997 using an average 10 per cent inflation figure, the Cross Harbour Tunnel toll by that date would theoretically be about $45.

That suggests that future users of the Western Harbour Crossing will be getting a bargain at $30 a car, when inflation is taken into account.

As the Government has rightly pointed out, even this toll of $30 in 1997 dollars is only equivalent to $20 in today's currency - after allowing for inflation.

Of course, even the projections from 1972, using the original $5 toll, fail to take into account the additional $5 tax introduced by the Government in June 1984 for the Cross Harbour Tunnel.

If that tax is included in the calculation - assuming the tax also increased with inflation, and using a $5 toll from 1972 to 1984 and a $10 toll thereafter - motorists would be looking at a $37 toll per car today, if the overall charge had risen with inflation.

Moreover, if this indexation is carried through to 1997 - again, using an average 10 per cent inflation - then motorists would be looking at a theoretical $60 toll for the Cross Harbour Tunnel.

That is double the 1997 dollars toll proposed for the new Western Harbour Crossing. This again suggests that future users will be getting a bargain.

Of course, the effective ''economies of scale'' of the Cross Harbour Tunnel have changed dramatically over the intervening years.

What makes the tunnel viable for the operators at $5 per car, or $10 including the tax, is the volume of cars using the facility.

Without that increase in volume of cars, the tolls being charged for all vehicles would have had to be raised years ago, although not in line with the rate of inflation.

Over the same period, too, the cost of construction, and financing, of tunnels has gone up considerably.

It is, therefore, understandable that both the future operators of the Western Harbour Crossing and the Government have had to look to a $30 toll for each to use the tunnel in 1997.

This is especially the case if - as with the Cross Harbour Tunnel and the new Eastern Harbour Tunnel - it took some years for the volume of traffic to build up to a viable level.

To be sure, the Eastern Harbour Tunnel volume took a far shorter time to increase than did the volume in the Cross Harbour Tunnel.

But there are no guarantees for the future builders and operators of the Western Harbour Crossing that the traffic will build up at the same, or better, rate than for the two other tunnels.

Economists, analysts and traffic planners can do the most meticulous studies they like in an attempt to predict the likely traffic flow through the tunnel and the likely revenue raised, but no one can predict the state of economy at the time of the opening.

This point is critical when considering the fact that a lot of cross harbour traffic is business orientated.

The Western Harbour Crossing will also have to compete with the existing tunnels at probably lower tolls, as well as the even less expensive cross harbour vehicular ferry services.

Put another way, the original, and present $5 toll - without taking account of the $5 tax - is only equal to 75 Hongkong cents today in real terms (that is, 1972 dollars).

It would be impossible for any contractor today to build the Cross Harbour Tunnel and then charge a $5 toll for each passenger car, let alone 75 cents at today's inflation adjusted values.

WHEN the preliminary Hongkong trade figures for May were issued on June 29, there was some justifiable concern about the slowing in the growth rate of exports.

These figures show that total export growth in May slowed to 11.1 per cent over a year ago, re-exports growth had slowed to 17 per cent year-on-year and domestic exports were actually down 6.5 per cent on a year earlier.

Various theories - the state of the global economy, the downturn in Europe and overheating in China - were put bandied about to explain the slowdown at the time.

Analysts also attempted to assess whether the May figures were a one-month aberration, or an indication of a slowdown still to come.

Unfortunately, no one followed through on the country-by-country breakdown of the figures issued on July 12.

It is difficult to assess anything very much from one month's figures, but what the country breakdown does appear to show is: the slowdown in the rate of growth of re-exports cannot be slotted home to an easing off in demand in one country or region.

having said that, however, there was a marked slowdown in the growth rate of re-exports going to China since the beginning of the year.

there had also been a marked slowdown in re-exports growth to Europe, although US and Asian demand has generally remained strong.

The one exception in Asia is Taiwan, where there had been a downturn in re-exports for several months, although the rate of decline had diminished greatly from the slump in February, March and April.

As far as domestic exports are concerned, a similar pattern emerges, with the decline being spread fairly widely, rather than attributable to one country or region.

What can be said, however, is that domestic exports to China did maintain their positive pace of growth in May - albeit at a slower rate than previous month.

This would suggest the overheating of the economy and its inflationary effect on products sold had shown little impact on the demand for Hongkong goods in China up to the end of May.

But the slowing in the pace of growth may be a signal of what to expect in the near-term future.

The really negative performance, as far as domestic exports are concerned, has been in the markets of Europe and North America.

But, with these markets still struggling to maintain their own economic growth - one slipping into recession, the other trying to get out of it - little improvement is expected.

In Asia, on the other hand, both Singapore and Malaysia have maintained their strong rates of growth in the purchase of Hongkong domestic exports.

Ian Perkin is chief economist with the Hongkong General Chamber of Commerce. The views expressed in this column are his own and may not necessarily reflect Chamber Policy