I-35 is the only major interstate that runs through Central Texas and right between Belton and Jarrell it's a big a parking lot.
From the air you can see the backup that starts at the accident scene in Salado.
According to some traffic guides, the congestion to the south for northbound drivers starts to build up around Jarrell.
To the north of Salado for southbound traffic that appears to be coming to a stop around Belton.
There are two quick detours to consider.
To the east is HWY 95 that runs from Elgin through Taylor around Salado to Temple.
From there you can work your way back to I-35, you can go all the way to Temple or cut back west on HWY 436 at Little River Academy.
To get to HWY 95 from Austin you can take HWY 290 east to Elgin.
From Round Rock you can take HWY 79 or can go on up to Georgetown and get to 95 by going east on HWY 29.
A possible west side route to consider involves taking HWY 195 in Georgetown.
That road will take you to Killeen.
From there turn east on HWY 190 and head toward Belton, once there you will be able to re-connect to I-35.
Be aware traffic will be building up on those routes, so you could venture even farther west by taking HWY 183 and HWY 281.
Both those roads will get you up toward the metro-plex.