Someone asked me, "How can the PRT be more efficient than the MRT?" The MRT has economy of scale and should use less energy. I think that the PRT can be more efficient because:

1. the number of podcars can vary according to demand.

2. the podcars can go straight to the destination, without having to stop at the intermediate stops

A Transportation Enthusiast provided the following useful information for my calculations:

> Consider weight alone as a rough estimate of energy usage. This is not fully accurate, but can give a ballpark number for energy efficiency.

> According to Wikipedia, MRT trains weigh about 214,000 kg unloaded and can carry a maximum of 1920 passengers (492 sitting, 1428 standing).

> A ULTra PRT weighs about 700kg unloaded and carry 4 passengers.

I will approach the calculation in this way:

> Train 214,000 kg / 1920 passenger = 111 kg p passenger

> Podcar = 700 kg / 4 = 175 kg p passenger

Assume an average occupancy of 50% during the peak and off-peak hours.

> Train (50% occupancy) = 222 kg p passenger

> Podcar (50% occupancy) = 350 kg p passenger

We have to consider the energy used in starting and stopping the train. Assume that this adds to an additional 20% in energy use.

The final adjustment is for distance travelled. The podcar can take the direct route and cut down the distance. The train follows the same schedule and forces all passengers to travel longer. Assume that the difference in distance is 30%.

The final energy consumpiton is:

> Train 222 X 1.2 X 1.3 = 346 kg p passenger

> Podcar = 350 kg p passenger

Both train and podcars can probably consume the same energy.

The podcar beats the train in the following respects:

> Shorter travelling time, due to direct route

> All passengers in the podcar are seated.

If the podcar can be filled with 4 passengers (through pod-pooling, to reduce cost per passenger), the pod beats the train in energy consumption as well.

Disclaimer: This is just a simple calculation. It is based on assumptions that may differ in actual practice. Take the conclusion with a pinch of salt!