Learn Hardcore Finnish: Me ollaan puhuttu siitä, miten jalankulkijat ja pyöräilijät voisivat kunnioittaa toistensa tilaa paremmin. - We have talked about how pedestrians and cyclists could respect each other’s space better.

Grammatically, ollaan puhuttu looks like a passive perfect (“has been talked”), but in speech it’s used as 1st person plural (“we have talked”). This is extremely common in colloquial Finnish, especially with me and te:

Me ollaan nähty = Me olemme nähneet = we have seen
Te ootte käyneet = Te olette käyneet = you (pl.) have visited

What exactly is the form puhuttu, and how is it formed from puhua?

Puhuttu is the passive past participle of puhua (“to speak, to talk”).

Formation (verb type 1 like puhua):

Take the verb stem: puhu-
Add the passive perfect ending -ttu/-tty
→ puhuttu

This participle is used:

in the passive perfect:
- On puhuttu siitä, että… = “It has been talked about that…”
in spoken plurals like in your sentence:
- me ollaan puhuttu (spoken) ≈ me olemme puhuneet (standard)

For comparison:

syödä → syöty
pelata → pelattu
kirjoittaa → kirjoitettu

Why is it puhuttu siitä, with siitä? What case is siitä, and why is it used here?

The verb puhua normally takes the elative case (-sta/-stä) for what you talk about:

puhua jostakin = to talk about something

Se (“it, that”) in the elative is siitä (“about it / about that”):

puhua siitä = to talk about it / that

So in Me ollaan puhuttu siitä, miten…, siitä is:

the pronoun se in elative,
required by the verb puhua,
and it points forward to the following clause starting with miten (“how”).

Functionally, the whole thing means “We’ve been talking about how…”

What is the role of miten here, and why is there a comma: siitä, miten jalankulkijat…?

Here, miten introduces a subordinate clause that explains what you have been talking about, namely how something could happen.

Structure:

Main clause: Me ollaan puhuttu siitä, …
Subordinate clause: miten jalankulkijat ja pyöräilijät voisivat…

In English, this is similar to:
“We’ve been talking about how pedestrians and cyclists could…”

In Finnish, a comma is usually placed before a subordinate clause that starts with a linking word such as että, koska, kun, jos, vaikka, miten, etc. So the comma before miten is the normal rule.

Could we use että instead of miten, like siitä, että jalankulkijat ja pyöräilijät voisivat…? What is the difference?

Yes, you can also say:

Me ollaan puhuttu siitä, että jalankulkijat ja pyöräilijät voisivat kunnioittaa toistensa tilaa paremmin.

The nuance is:

siitä, miten… = “about how …” (focus on the manner / way / method)
siitä, että… = “about the fact that …” (focus on the existence of the situation)

Your original sentence:

siitä, miten jalankulkijat ja pyöräilijät voisivat kunnioittaa…
→ more about the ways in which they could respect each other’s space.

With että:

suggests you’ve been talking more generally about the idea or fact that they could/should respect each other’s space, not necessarily about the specific methods.

Is there a difference between miten and kuinka here? Could I say kuinka jalankulkijat ja pyöräilijät voisivat…?

You can say either:

miten jalankulkijat ja pyöräilijät voisivat…
kuinka jalankulkijat ja pyöräilijät voisivat…

In this meaning (“how”), they are largely interchangeable.

Nuances:

miten is more common in everyday spoken Finnish.
kuinka often sounds a bit more formal, bookish, or stylistically elevated, although in many contexts it’s completely neutral.

So your sentence would still be correct and natural with kuinka, but miten matches the colloquial style of me ollaan puhuttu better.

What does jalankulkijat look like grammatically? How is it formed?

Jalankulkijat is:

the plural nominative of jalankulkija (“pedestrian”).

Formation:

singular: jalankulkija (a pedestrian)
plural nominative: jalankulkijat (pedestrians)

Ending:

the -t at the end marks the plural subject in nominative case.

So in the subordinate clause:

jalankulkijat ja pyöräilijät = “pedestrians and cyclists” (two plural subjects joined by ja / “and”),
which explains why the verb is voisivat (3rd person plural).

What form is voisivat, and why is the conditional used here instead of voivat?

Voisivat is:

the 3rd person plural conditional of voida (“can, to be able to”).

Conjugation (3rd person plural):

present: he voivat = they can
conditional: he voisivat = they could

In your sentence:

jalankulkijat ja pyöräilijät voisivat kunnioittaa…
= “pedestrians and cyclists could respect…”

The conditional is used:

to express possibility or potential (“could, would be able to”),
and often softens the statement, making it sound more polite, suggestive, or hypothetical rather than a blunt statement like “they respect”.

Voivat (“can”) would feel more factual/strong:
“how pedestrians and cyclists can respect…”
Voisivat implies: in what ways they could (possibly) respect each other’s space better.

What is toistensa exactly, and how is it different from toisten?

Toistensa comes from toinen = “(an)other, one another”.

With plural people, toinen is used for reciprocal meaning: “each other, one another”.

Forms:

toinen = another / the other (sing.)
toiset = the others (pl. nominative)
toisten = of (some) others (genitive pl.)
toistensa = of each other / each other’s (reciprocal genitive pl.)

So:

toisten tilaa = the space of (some) others
toistensa tilaa = each other’s space

In the sentence, we want “each other’s space”, because pedestrians and cyclists are mutually respecting each other’s space, not just the space of some random other people. Hence toistensa.

Why is it toistensa tilaa and not toistensa tila? What case is tilaa, and why is it used here?

Tilaa is the partitive singular of tila (“space”).

The reason is the verb kunnioittaa (“to respect”). It typically takes its object in the partitive case:

kunnioittaa vanhempiaan = to respect one’s parents
kunnioittaa lakia = to respect the law
kunnioittaa toisen mielipidettä = to respect someone’s opinion

So here:

kunnioittaa toistensa tilaa
→ tilaa must be partitive, because that’s how kunnioittaa governs its object.

If you said toistensa tila, it would sound ungrammatical or at least very odd to a native speaker.

What is paremmin grammatically? How is it related to hyvin or parempi?

Paremmin is an adverb, the comparative form of hyvin (“well”).

Paradigm:

hyvin = well
paremmin = better (adverb)
parhaiten = best (adverb, superlative)

Adjective equivalents:

hyvä = good
parempi = better
paras = best

So:

kunnioittaa toistensa tilaa hyvin = respect each other’s space well
kunnioittaa toistensa tilaa paremmin = respect each other’s space better

In your sentence, paremmin modifies the whole verb phrase kunnioittaa toistensa tilaa.

Why does the verb voisivat come after the subjects (jalankulkijat ja pyöräilijät voisivat) instead of before them, like miten voisivat jalankulkijat ja pyöräilijät…?

Finnish word order is quite flexible. Both are grammatically possible:

miten jalankulkijat ja pyöräilijät voisivat kunnioittaa…
miten voisivat jalankulkijat ja pyöräilijät kunnioittaa…

The most neutral, everyday order in a statement is:

Subject + Verb + (rest)
→ jalankulkijat ja pyöräilijät voisivat kunnioittaa…

Putting the verb before the subject (voisivat jalankulkijat ja pyöräilijät) often feels:

more emphatic, stylistic, or poetic, or
like a question in speech, depending on intonation.

So the chosen order here is the most natural for a neutral explanatory sentence.