Vital Signs: Travel Time Reliability – by corridor

VITAL SIGNS INDICATOR Travel Time Reliability (T9) FULL MEASURE NAME Freeway buffer time index LAST UPDATED May 2017 DESCRIPTION Transportation planners quantify the travel time reliability of a given route by means of a buffer time index (BTI). BTI is a measure of the amount of time, over and above the average travel time, that a driver would need to budget to ensure on-time arrival at the desired destination, with a 95 percent confidence rate. BTI is expressed as a fraction of the average travel time – the lower the BTI, the more reliable the trip. This measure focuses solely on the regional freeway system, as no comparable data is available on the local street network. The dataset includes metropolitan area, regional and freeway corridor tables. DATA SOURCE Metropolitan Transportation Commission/INRIX: Freeway Reliability Analysis California Department of Transportation: Annual Traffic Volume Reports http://traffic-counts.dot.ca.gov CONTACT INFORMATION [e-mail] METHODOLOGY NOTES (across all datasets for this indicator) Buffer time index was calculated based on the average reliability of each freeway segment over the course of one-hour time windows. Peak periods were defined as 6 AM to 10 AM and 3 PM to 7 PM. Regional BTI was calculated using traffic volumes on each segment and weighting BTI accordingly across the network.