Yes, but (at least in my experience) pensioners don't tend to ride around all day on crush loaded services.
They ride around on the marginal services you describe.
So they do not significantly increase the peak service loading.
As once the busses crowd out the pensioners go home because its not that comfortable any more.
Beyond that, demand beond the route's carrying capacity is
entirely irrelevant.
It doesn't matter if a quadrillion people are at the bus stop ,if the bus can only embark 30 more people then we only have to pay to carry 30 more people.
And thus when the calculations are done they can make the case for additional bus capacity.
But this is additional spending beyond the ~£3.3-£3.5bn that I outlined. I would argue that spending more would be better, considering the potential for environmental benefits - but that doesn't change the fact that you could abolish bus fares for the amount I said.
Well if you take out
all the seats you can crush in 170 or so people.
JUst like I have seen rather more than 80 people fit onto a double decker.
EDIT:
Since TfL was crowing about (regular) hybrid buses managing 6.1mpg in an urban environment
7-8mpg sounds rather
optimistic.
EDIT #2:
As to the price of vehicles, as of 2008, from the American document '
Use of Higher Capacity Vehicles in Transit Service' [which you can download as a guest just be giving an email].
It can be seen that an Alexander Dennis E500 (a three axle double decker) was actually around the same price as a variety of articulated vehicles (see page 47/80) so it is does not appear significantly different.
I will look up for figures associated with a two axle decker but these figures are obviously hard to find.
EDIT:
A handy table on page 49/80 of the same document shows a figure of 3mpg(US) combined transit service fuel economy for an articulated bus, versus 2.8mpg(US) in combined transit service for thre three axle double deckers.
3mpg US is ~3.8mpg Imp, which compared with the TfL figure above indicates that comparison of pure diesel artics versus pure diesel deckers gives us a comparison of
3.8 versus 5.3.
Even at 130 people versus ~85 the articulated vehicle still wins on fuel consumption per passenger (marginally).
EDIT:
Volvo claims that the 7900 Hybrid Articulated bus has a capacity of 154 with seats still in.