I've wondered myself that since April and I've come to the conclusion it would take a lot of missiles and it would only put those roads and railways out for at least a couple days. Is it worth it if you're just hitting the road and railway and not the actual weapons? Targets like that need to be taken out by aircraft carrying 2000lb+ of ordinance to really mission kill it for more than a week or two. That's how the US does it no cruise missile for such targets always aircraft.
This is not entirely true, at least with regard to railroads.
This Western aid could have been drastically reduced if the Russians had done their job. It is not possible to reduce deliveries to zero due to the extension of the common border and the developed road transport network. But the AFU clearly needs fuel and other supplies from the West, so the delivery of equipment, ammunition and other military equipment is mainly carried out by rail, as close as possible to the troop concentration areas. The target of these attacks should have been infrastructure located in close proximity to western borders in Ukraine. What the AFU will definitely not be able to do quickly is restore the destroyed railway bridges, that takes a long time to rebuild.
Just make an analysis of all rail corridors between Ukraine and neighboring countries. And in each of these corridors, a critical point was found in the form of a railway bridge, the failure of which would paralyze the transport line and significantly complicate railway logistics.
The following is the ideal list of railway bridges, whose single failure will paralyze the rail supply of western countries. A total of 21 bridges would need to be decommissioned. If at least one of the bridges survives, the AFU will still have the opportunity to deliver weapons and military equipment to Ukraine by rail.
Vinnytska region -
railway bridge (Mohyliv-Podilskyi settlement) - 48.460294, 27.766381
Border bridge over the Dniester River (Mohyliv-Podilskyi settlement) — 48.449110, 27.779921
Volynska region -
Double railway bridge (Kovel settlement) — 51.226367, 24.700441 | 51.228894, 24.700672
Railway bridge over the Putylivka river (Romashkivka settlement) - 50.781638, 25.804592
Railway bridge over the Stokhid River (Goloby settlement) - 51.029249, 25.108861
Railway bridge over the river Stokhid (Zayachivka settlement) - 51.282653, 25.206144
Transcarpathia Region -
Double rail bridge over the Vecha River (Volovets settlement) - 48.710053, 23.155696
Railway bridge (viaduct) over the Uzh River (Uzhok settlement) - 48.985140, 22.843154
Railway bridge over the Tisza River (Kruhlyi settlement) - 47.963468, 24.189143
Lviv region -
Double railway bridge over Vereshytsya River (Kam'yanobrid settlement) — 49.842649, 23.651923 | 49.843007, 23.651934
Railway bridge (Stryi settlement) — 49.244127, 23.856522 | 49.269314, 23.886442
Railway bridge over the river Mlynivka (Zavady settlement) - 50.074812, 23.896215
Railway bridge over the Rata River (Mezhyrichchya settlement) - 50.343717, 24.231357
Railway bridge over the river Dniester (Sambir settlement) - 49.506856, 23.222314
Railway bridge over the Strvyazh River (Khlopchytsi settlement) - 49.605139, 23.415355
Odessa Region -
Railway drawbridge on the coast of Odessa (Karolino-Bugaz-Zatoka settlement) - 46.076304, 30.469847
Others -
Bridge over the river Dniester in Khmelnitsky (Makarovka-Velyka Slobidka settlement) - 48.555192, 26.743138
Bridge over the river Siret in Cherepkovtsy (Staryi Vovchynets settlement) - 48.014033, 25.959089
Bridge over the Stalyneshty River in Chernivtsi (Novoselyts'kyi settlement) - 48.242906, 26.541793
From what I remember of that war, the Russians probably only attacked the bridge in the Odessa region more than once, but they didn't do the same with the other bridges.