Railroads need repair too? Not sure if it's every 4 years. Also, the trains I take to/from work are super slow because there is no money to upgrade.

I think we may not upgrade every 4 years, but instead upgrade when the AI models are not meeting our needs AND we have the funding & political will to do the upgrade.

Perhaps the singularity is just a sigmoid with the top of the curve being the level of capex the economy can withstand.