Transportation Requirements: Reliability

One requirement of any transportation system is that it be reliable--absent reliability, people on inflexible schedules who have a choice of transportation mode won't choose public transit. In order to test the reliability of public transit in northern Virginia, we used an Apple iPhone with GPS enabled to capture (see photos below) the arrival times on four randomly selected stops served by the Fairfax Connector.

How reliable is public transport in Northern Virginia? In our sample, the best arrival was one minute late, the worst was 11 minutes late, with a seven minute average. When routing passengers with connections, the local transit Route Planner builds in five minutes between arrival of one segment and departure of the next segment, which means with this seven minute average delay, most connections would be missed. While this sample size is too small to give any confidence in the level of system reliability, a seven minute delay is a cautionary indicator that calls for closer examination.

Date.time (yymmdd.hhmm)	LatLong	Stop	Scheduled	Route	Late?
110805.1133	38.9165, -77.220667	Tysons Corner Shopping Center	11:32	FC402	1
110806.2102	38.895667, -77.225	Gallows Rd & Elm Pl	20:54	FC401	8
110806.2107	38.916333, -77.221333	Tysons Corner Shopping Center	20:59	FC401	8
110806.2233	38.914333, -77.221667	Tysons Corner Shopping Center	20:22	FC402	11
					7

- Stuart M. Whitaker