Maybe "tomo tawa kulupu" 'group travel space'
> train,
Maybe "tomo tawa linja" 'long stringy travel space' (or alternately "tomo tawa pi kiwen linja tu" 'travel space of two stringy solids')
> airplane,
I've previously used "tomo tawa kon" 'air travel space'
> elevator,
Maybe "tomo tawa anpa" 'downward travel space'
> shipping container,
Maybe "tomo tawa esun" 'commercial travel space'
> bobsled...
Maybe "tomo tawa pi telo lete kiwen" 'hard cold water's travel space'
I'll also add that there's been some debate between "tomo tawa" 'travel building, travel space' and "ilo tawa" 'travel tool' for vehicles. I would certainly regard a bicycle as an ilo tawa because you don't enter inside of it. (A problem with "tomo tawa" is that "tomo tawa kon" 'air travel space' is arguably ambiguous between an airport and an airplane!)
Although toki pona is super-bad for any kind of precision, you can often figure out how to express more than you might first think. :-)