Different cities around the world deploy road charges in different ways – each model with its own pros and cons.
Heavy-Vehicle Bypass System
Some cities, such as Atlanta in the United States, designate a highway lane as heavy-commercial-vehicle only.
The trucks using the lane pay a fee; the rest of the traffic rides free. The system reduces congestion, allows trucks a free ride through the city, and by separating cars and trucks, reduces the likelihood of a car-on-truck crash.
However, some research points to truck companies’ wariness of toll roads. According to an American study, freight needs to realise significant benefits in reduced travel time and fuel costs from reduced congestion in order to make tolls cost-effective. This calculation is made more difficult because heavy vehicles generally pay a much higher toll than car drivers – especially if they’re the only ones being tolled and the cars are driving free.
Of course, this is generally true of toll roads; they need to be significantly better than the alternative for drivers to be willing to pay to use them.
HOT Lanes
High-occupancy-toll-lanes offer no fee or reduced tolls to cars with a certain number of occupants. As the number of occupants decreases, the toll charge increases. This system is designed to reduce single-occupant car trips and encourage car pooling, which reduces congestion.
Allowing drivers to choose their lane – and toll – means they can make decisions that suit them; someone in a hurry might choose to drive in the HOT lane and pay the toll, for example. However, HOT lanes compete directly with public transport for passengers choosing not to drive a car, which may not be desirable.
Conventional vs variable
Some cities run toll roads with a variable charge that increases and decreases based on time of day and total amount of congestion on the road. This type of tolling is operated on some roads in Sydney.
A major risk faced by the constructors of toll-roads is over-optimism.
Toll road operators bid for government contracts based on their own models of how many users will use – and be charged for – the new road. But these forecasts can sometimes be inaccurate.
Brisconnections’ $4.8 billion toll road in Brisbane fatally overestimated traffic volumes, leading to the company going bankrupt, with taxpayers ending up footing the bill.
Sydney’s Cross-City Tunnel has been in receivership twice after its total traffic numbers were less than a third of those its optimistic modellers originally predicted.
