Why demand for transport is a derived demand

Well, first of all:

Derived demand - demand for a good or service not for its own sake, but for what it produces.

In case of transport we can see 2 types of derived demand for transport:

1st is passenger demand, usually we need transportation to our workplaces, shops, schools, red bull factories etc. we need no ride on bus\car\train\whatever itself but we need to be somewhere. this is the final product of transport - getting somewhere you need to get.

2nd is freight transport demand. The companies usually transport all sorts of goods around the world not because they like how lots of boxes with Red Bull cans look in the vehicles\huge containers, but because their consumers want to get it. Or somebody needs raw materials to produce their good, let's say, books. Transportation itself is not doing anything to the product, but eventually the raw materials get from A to B - and that is what demanded, that is what the final product of transport.

Characteristics of the main modes of transport

Passenger transport:

Private car.
Advantages: most flexible and convenient, the only mode of transport that is able to give door to door service, is used for all types of journey purpose, can carry luggage and shopping stuff
Disadvantages: the least environmentally friendly type mode

Advantages: most effective on the main corridors in large towns and cities, most attractive (when there are short waiting times)
Disadvantages: users are limited by the service provided

Advantages: speedy carrier of large volumes of passengers, very effective on middle and long distances, has a good access to the cities
Disadvantages: may not be so effective on short distances

Advantages: moving passengers over longer distances at speed
Disadvantages: limited use for internal transport in th UK, but widely used elsewhere

Freight transport:

Road vehicles.
Advantages: convenience, flexibility, connectivity + is suitable for carriage of the most goods
Disadvantages: environmental problems arise, dependence on congestion levels

Advantages: best suited for moving bulk loads, efficient and speedy for transporting over distance
Disadvantages: the problems of interchange can reduce its efficiency

Advantages: appropriate for moving time-sensitive and expensive cargo, mainly over long distances
Disadvantages: not so effective on short distances (?)

Advantages: cheap, moves bulk cargoes & containers
Disadvantages: quite slow, efficient mainly on long distances