What does this sentence mean?? '' the distribution between modes has tipped sharply in favour of road transport since the 1990s. '' [closed]

...the distribution between modes has tipped sharply in favour of road transport since the 1990s

In this case 'modes' is referring to modes of transport (road, rail, river, etc.). The 'distribution between modes' is therefore referring to the relative share (of all transportation) that each of the modes has.

So the quoted sentence is stating that since the 1990s these relative shares have changed with road transport now having the greatest proportion.