see it this way
The Singapore roads are very buumpy. Even the F1 racers think so
in Sep 2008.Allmost everywhere u see roads dug up for powerline and
pipe maintenace or replacement. Roadworks abound everywhere.
In other coountries, roads are less buumpy and bus
suspensions work less.
In Siingapore, most bus suspension use air suspensions. This
greatly reduces the bumps n joingz (is that even a word?)
u feel on the road. The air suspension cannot totally eliminate all
Singapore roads bumps.
recently even new bus model with offerings like 4 suspension
pads 9comapred to two on msot older bus models) at rear
cannot do much. This i refer to the MAN 18.240HOCL SBS80321J or i
think the SMRTbuses OC500LE offerings.
In order to get a feeling of how a bus suspension REALLY reduces
the bumpy and jerky ride, you have to go overseas. In malaysia
roads are sometimes better. A ride on the old school
Mercedes buses there through well paved village roads will
show you the true power of a Mercedes
Suspension.
ZYX
Hi ZYX, as far as i know, starting from the B10M MKII, there
were 4 airbags per rear axle, that includes the CRBs and O405s.
Even the O305s have them.
Anyway, the airbags aren't there to absorb bumps. Its meant to
absorb vibrations and small jolts. Bumps are absorbed by the shock
absorber, which were placed side by side with the airbags. 2 per
front axle and 4 per rear axle.
That said, the pressure inside the airbag also cannot be too
high, otherwise it would become so stiff that its practically "no
suspension". It has to work side by side with the shock absorber to
produce a smooth ride.
Anyway, I've ridden an old sch merc at malaysia before, on both
paved road and unpaved road. And yeah, its a great merc suspension,
until my bus rode over a huge pot hole. 
The
entire goes "poom!" and shook everyone violently, but suprisingly
tho, nothing of the bus suspension or axle is damaged. Still can
cruise on highway smoothly like its brand new.
