The costs associated with throttling/halting these sectors far outweighs the cost of overbuilt infrastructure. Electricity is already sold by the megawatt in "day ahead" commodity form so businesses have already priced this information into the market.
[1] http://en.wikipedia.org/wiki/Electric_energy_consumption#Ele... [2] http://www.eia.gov/todayinenergy/detail.cfm?id=10211
Can everyone dynamically shift business routines due to "demand"?
There's no particular reason emergency service shift changes need to be synced to the common business day -- indeed, my intuition would be that accident timing patterns would make this a bad idea independent of traffic impacts -- but there's also no reason that employers with employees for which they have strong fixed-time needs couldn't subsidize (or, in the case of public necessity where the employer is the government, exempt) their employees traffic fees.
> Can everyone dynamically shift business routines due to "demand"?
Yes, they can -- but, of course, there is a cost (which varies from situation to situation) in doing so. Of course, there's also a cost -- particularly an externalized cost born by others -- of traffic. If you effectively internalize the external cost (i.e., make it born by the people making the decision to engage in the action), then behavior should reflect the true costs and benefits resulting from the action.
I remember an enlightening graph of power grid demand over a year sorted by demand. (Which I can't find for the life of me.) The vast majority of the time is spent very near the average, but a very small amount of time needs almost twice the average, and another very small amount of time demands half the average. The problem is, the grid must be big enough to supply that 3-times-a-year double the average demand, which just sits there idly the rest of the year.
I imagine demand for transportation is similar though not as exaggerated.