Papa, how come the bus so expensive hah?

'No leh. It's cheap cheap. Gover-ment say, only increase by little bit only leh.'

Yes.

They have this rather interesting model that they expect families of lower than average (median, not mean prolly) incomes to follow with respect to their transport habits.

From the appendix of the REPORT OF THE COMMITTEE ON THE FARE REVIEW MECHANISM, www.mot.gov.sg/policy-land.htm:
"Based on the 1997 HIS results, the majority of trips made on public transport consist of home, school and work place as their destinations. These trips are made on both the bus and RTS. To ensure that the travel profile of the characteristic family captures the trips made on different modes, the travel pattern of the characteristic family has been designed to include a mix of rides on feeder and trunk buses, as well as the RTS. To further monitor the change in fares across different fare types, the travel profile also captures both the adult and concession fares. In addition, the family’s total monthly expenditure on public transport has also been cross-checked against the HES findings on the second quintile’s household expenditure on public transport.

The following summarises the weekday travel pattern of the characteristic family:
• One of the working adults commutes to/from work by RTS and the other, by trunk bus;
• The adults travel 12.4km and 6.6km respectively by RTS and bus. These are the average trip lengths in 2003;
• The RTS trip made by the adult requires the use of a feeder bus to make a transfer; and
• The child in the secondary school commutes to/from school by bus using a concession pass and the child in the primary school walks to a school nearby.'

Calculations on how much these families spend on transport are then made based on this model. So, all working adults only travel on buses for work. The secondary school pupil only ever goes to school. And the primary school kid only ever walks.

Now, erhem, how "characteristic" exactly is this family?