They always should have just built an extra lane or two and kept the hard shoulder.
Probably would have been cheaper too
My understanding is that it costs far more money to retrospectively go back and add an extra lane than to build it with the extra lane to begin with.
Back in Victorian times we seemed to grasp these big projects with a "Can do" style attitude and approach which is why we were world leaders, where did it change to the "It will do" penny pinching non progressive approach

I don't know the figures so may be wildly out but someone once told me that building a 3 lane motorway may cost say £10M / mile but building it 4 lane is only slightly more at say £11M as they often buy up the required land anyway just in case expansion is needed at some point.
My argument is why aren't we automatically building this stuff 5 or 6 lane

I'm aware of a road that was built just over around 35 years ago and was constructed as a combination of 2 and 3 lane rather than duel carriageway as it was "Cheaper"
Even back then everyone was saying how short sighted it was and likely to be dangerous as 40 years before these 3 lane sections with a shared overtaking lane was known as "The coroners corridor"
It's taken them another 35 years to now start upgrading sections to DC but obviously not all of it due to the cost

I recall tales of bridges that were going to be built and town bypasses etc during WW2 that are only now just being put into action, back then the Americans were going to build them as they could see they were needed for the war effort and in some cases they just got on with it and got it done.
The plans that didn't happen in time were put on ice for another 50 years or so