M5 J8 slip south

Anyone on here with inside info on why this slip is reduced to one lane,which is now causing traffic to backup to J10a on a daily basis which according to info boards is going to last til oct 2018,bearing in mind it was only two years ago or so it was the same for a year while they worked on concrete sub base/drainage/new road base,or is it to do with the 40mph limit towards J1 M5, now all traffic is fired out into lane 3 while every man and his dog is under taking you at 70 as you try to get back into lane 1,seems bonkers but there must be a logical explanation,captain?

They’ve got nowhere to store the cones.

My boss pays for the toll motorway, get a discount if have a lot of motors, the amount of time,fuel and wear and tear lost stuck in that cluster ■■■■ up.
The only issue is using the toll then hit rush hour on the M42 .
The so called road works around Birmingham motorway network is a national disgrace.
The routes are major international connecting routes, and only one lane open.
How can it take years and years to finish a job, when its done, they start again near to where they finished. ?