Section 490.609 - Data requirements(a) Travel time data needed to calculate the Freight Reliability measure in § 490.607 shall come from the travel time data set, as specified in § 490.103(e) .(b) State DOTs, in coordination with MPOs, shall define reporting segments in accordance with § 490.103(f) . Reporting segments must be contiguous so that they cover the full extent of the directional mainline highways of the Interstate in the State.(c) When truck travel times are not available in the travel time data set (data not reported, or reported as "0" or null) as specified in § 490.611(a)(1)(ii) for a given 15 minute interval, State DOTs shall replace the missing travel time with an observed travel time that represents all traffic on the roadway during the same 15 minute interval ("all vehicles" in NPMRDS nomenclature).(d) If an NHS roadway is closed, the State DOT is not required to include those time periods for those segments of road in the calculations required for the Freight Reliability metric/measure.