I'm on T17 as Soviets 1941-45 GC, Sudden Death, Normal, Art plus 1, SU plus 1 reduced Blizzard effects and no Soviet combat bonuses.
Um I've had Soviet SU RR Construction Brigades repair rail line hexes as close as two away from German Divisions, including stacks of 2 Panzer Divisions and triple stacks of mixed German Divisions, although all were cut off and had been for several turns, so not prevented within 5 in these cases.
On T15 I finished off the pocket battle of Minsk & Yuratishi which eliminated Panzer Group 3 and parts of 2 while on T16 I finished off the rest of Panzer Group 2 in pocket battles of Slutch & Baranovichi and in the greater Rovno area the last of Panzer Group 1.
At Minsk on the start of T12 there was the 29th Motorised Division just NE of the city (Hex X69, Y56) and the railway was being repaired from the Berezina at Smolevichi town Hex by a West Front RR Construction Brigade to Minsk at Hex (X71, Y56) so within 2 hexes range. But while both Minsk itself and the hex East of it (Hex X67, Y57) were undamaged they still seemed to wait a while after that turn (T12) when I pushed 29 Mot Div back west one hex onto a triple stack hex NW of Minsk which included two Panzer Divisions, 4th & 12th IIRC and only just just re-connected the line on T15 there in the hex west of Smolevichi with this time a Romanian RR Construction Battalion Hex (X70, Y56), so again within 2 hexes range of the German stack at NW of Minsk hex (X68, Y56). This Romanian RR Battalion from 3rd Rom Army was also 5 hexes range from a triple stack in the Hex East of the town of Slutch (Hex X68, 61) unless the 5 hex thing doesn't work on flipped Romanian RR Btlns.
At Baranovichi there was a two Panzer Division (10th & 18th Pz Divs) stack just SW of the town in Hex (X62, Y62) while for a few turns the rail line was repaired very near it starting from Gantsevichi town hex on T11 (Hex X65, 64) 4 hexes away from double PzDs, then 3 range away on T12 in hex NW of Gantsevichi in them light trees, then 2 hexes away in the town hex of Lyakhovichi on T13 and again 2 away on T14 at the angled T junction clear hex NW of Lyakhovichi. I have checked each and this was all done by West Front RR Constuction Brigades only (4th & 29th RR Bgds) no Romanians here in this region at all.
On T16 within both 2 & 3 hexes range of divisional stacks just East and SE of the town of Slutch hex there are RR Contruction Brigdes repairing the lines, before I destroy them and the two PzDs SW of Baranovichi, PzG 2 RIP.
Now I wish I could say the same as this about the SW Front area, but I can't, nada, nilch by them! I held out at the rough hex of town Lisko from T1 and the rail line to it from Sambor and SE towards Stanislav, also on the rough hex at Nikolaev two hexes south of Lvov, so looking at some of the damaged rail hex around here they have been from 10 to now 17 hexes away from German Divisions, and still no repairs anywhere here, with SW Front having four RR Construction Brigades in it at start of T17 and two in it start of T16! Luckily I held out around Kovel, even got pocketed, that I broke through to so that at least all the repairing the West Front and Reserve/Kalinin Front have done in and from the forward edge of the marshes has now extended the line one hex NW & SW of the town of Kovel. My railnet is four damaged hexes away from Breast-Litovsk with a West Front RR Construction Bgd at Drogchin (Hex X56, Y68) but I have just managed to be successful in storming from six sides and eliminated the 37 CV 267th German Infantry Division in B-L on this turn, T17.
In the greater or in this case lesser Rovno pocket area no SW Front rail repair have taken place yet either and I destroyed PzG 1 here last turn, what remains of AGS is behind and cut off beyond the Vistula!
But OTOH in the NW Front sector there are two RR Construction Brigades that have been repairing the railway within 2 & 4 hexes away from German Divisions and stacks of Divisions that appeared on T17, but there were earlier repairs that were carried out here earlier that were danger close too!
While all these examples are of German Divisions that were cut off I do remember earlier in this very game when a Soviet RR Construction Brigade repaired a railway hex only 2 or 3 hexes from supplied German Divisions just NE of Riga, when I managed to push back AGN from cutting off my Riga stalwarts, I'll check later though too be sure, but it was way earlier, well before I captured Memel on T12 and flipped the remaining Axis railnet behind AGN and basically won the game it feels, Urrah!
Hmmmm, interesting. You have some pictures of this? Are you on current patch?