That might take a week to build, it will be 104 m long. No bypass is possible, except driving all the way around Iceland. 
Icelandic Road and Coastal Administration (IRCA) has already started building a temporary bridge. Hence, the road might be passable again sometime in the weekend 6th to 8th of October. It is not possible to pass at the junction and there is no other route. The road to Jökulsárlón is just fine and no problem for tourists to visit that area, but it is impossible to drive onwards to Höfn.  It rained again the night before Saturday so the damage can not be estimated until today, Sunday. That is necessary to be able to react quickly when nature behaves as did earlier in the week. Work on building a temporary bridge is in full swing since IRCA has always material to build such a bridge handy and runs to teams of bridge builders. All depending on the work going well and no unexpected hurdles will occur. 
The old bridge is not safe since the amount of water due to heavy rain damaged one of the pillars of the bridge. noncleared-maintext”>
The Ring Road is closed at Steinavötn in Southeast Iceland, between Jökulsárlón and Höfn.