What is considered a “representative sample” in terms of data logging?
A representative sample of buses should include at least one bus of each group of buses with the same engine and all “worst case” buses. “Worst case” refers to buses where the bus route may not be sufficient to attain the required temperature profile. These routes will be mostly urban routes with a lot of stop-and-go driving and no or few hills. Worst case buses may also include those with alternate engine configurations. For buses where data logging is not individually conducted, a simple explanation, such as “same engine and similar route schedule as bus X that was data logged,” must be provided. The vendor also must affirm that those buses not data logged will meet the minimum temperature requirements for the filter and, therefore, will work effectively with the engine/bus. If you have a specific question as to how many buses comprise a “representative sample” to data log, please contact the program hotline at (703) 934-3040 or via e-mail at info@cleanbusesforkids.com.
