Under a plan approved last month by the NSW government, much of George St in Sydney's CBD is to be converted to a pedestrian mall. There will be few cars and trucks; there will be no buses. Instead, long light rail vehicles will connect Circular Quay to Randwick and Kingsford via Surry Hills. The NSW government says the project will generate about 10,000 jobs, with economic benefits to NSW at $4 billion, easily justifying the project's expected cost of $1.6 billion.

But there is an elephant in the tram. The light rail system described by the government won't have enough capacity for peak-hour passengers. The arithmetic is quite simple: 220 peak-hour buses, which conservatively carry an average 40 seated passengers, will initially be replaced by 20 light rail vehicles which the government claims can each carry 300 passengers. Squeezing 8800 bus passengers into 6000 light rail spaces might sound conceivable, but only 1600 of them will get seats.

The light rail system described by the government won't have enough capacity for peak-hour passengers: The elephant in the tram.

Worse, Sydney's light rail system has been designed in a way that will make any expansion expensive and disruptive. Transport for NSW needs to re-think its flagship plan and make major changes before construction starts in a few months' time.

According to the environmental impact statement published last year, the ultimate maximum capacity would be 30 vehicles each way per hour, totalling 9000 passengers per hour in each direction. There are two exaggerations in that official calculation.