Public Transport

Subways

Pros:

• Fast, as they don’t have to obey speed limits.

• Unaffected by weather.

• Can be automated, doing away with the need for drivers entirely.

Cons:

• Least pleasant to ride.

• Hideously expensive.

Elevated Rail

Pros:

• Fast.

• Safe, as it never comes into contact with pedestrians or other street traffic.

• Can be automated.

Cons:

• Expensive.

• The track is a major eyesore, and casts huge areas of shadow.

Monorail

Pros:

• All the benefits of elevated rail, but with a narrower, more attractive guideway that does away with the huge areas of shadow.

Cons:

• Just as expensive.

• Yet to gain any real credibility outside of Japan.

Light Rail

Pros:

• Long vehicles require fewer drivers.

• Vehicles can be connected together in trains for busy periods.

Cons:

• Still quite expensive.

• Unable to drive around obstacles.

Diesel Buses

Pros:

• Cheapest option.

• Also the most adaptable.

Cons:

• Smelly, noxious exhaust is hazardous to human health.

• Noisy.

• Lurching ride.

• Vibrations from the diesel engine.

Diesel-Electric Hybrid Buses

Pros:

• More fuel efficient than regular diesel buses.

• Reduce emissions by up to 40%.

• Quieter.

Cons:

• Still emit pollutants into the street.

Hydrogen Fuel-Cell Buses

Pros:

• Non-polluting.

• Quiet.

• No overhead lines required.

Cons:

• Very inefficient.  Using electrical energy to synthesise hydrogen, transporting that hydrogen, and then recovering electricity from it with a fuel cell is very wasteful of energy.

• Expensive.

• Unproven technology.

Trolleybuses

Pros:

• Non-polluting and quiet.

• Much smoother ride than diesel buses.

• Can leave overhead lines to bypass obstacles.

Cons:

• Even double articulated, they can only seat around 90 passengers.

• More expensive than diesel buses.

• Overhead lines regarded as an eyesore.

The Verdict

Subways, elevated rail and monorails are probably too expensive for towns and small cities.

Diesel buses are even louder and smellier than the fifty or so cars they replace.  Hybrid buses are better, but still pollute.  And hydrogen fuel-cell buses are massively wasteful of energy.

This leaves light rail and trolleybuses.  Both are non-polluting, both are very energy efficient, especially when equipped with regenerative brakes, and both offer smooth, quiet rides.  In short, both are excellent.  But which is best?

Trolleybuses score over light rail in reliability.  Fitted with auxiliary batteries, trolleybuses can leave the overhead lines completely to bypass obstacles such as broken-down vehicles or road works.  Light rail vehicles cannot.

But light rail has a major advantage of its own.  Light rail vehicles can be much longer, so each driver can transport many more passengers.

Thus in towns and small cities, the trolleybus should be favoured for its higher reliability.  But in medium size cities, the higher capacity of light rail makes it more or less essential.