PlanItMetro

Adopted from queueing theory, this new method of assessing delay on transit systems with tap-in-tap-out fare systems accounts for natural variations in customer behavior.

As you may have heard, Metro is testing out a new customer-oriented travel time performance indicator. Many departments here at Metro have been collaborating on this effort. Metro has decided to initially pilot a measure where we define delay as anything greater than train run time, a headway, and the 1-3 minutes it takes to travel from the faregates to the platform. However, as we began our research into customer travel time, we got to asking the question, “How do we define customer delay on the rail system?”

As we quickly learned when digging into the data, on good days with no delay on the rail system, there is still a wide variety of “normal” customer travel times. Some variation in travel time is because customers arrive at random to the origin station, but all leave the destination station more or less at once.  Additional factors influencing this variation include walking speed, use of elevator vs. stairs, escalator or elevator outages, and customers with suitcases and strollers.

We could start with a threshold for “on time” but by definition we know on a good day there were no rail delays so we would be counting slower customers as “late.”

Additionally, on a day when we know a disruption has occurred, we might count very quick customers as “on time” when in fact we know that everyone experienced some delay.

So we set to determine a method for calculating delay that accommodated for the natural variation in customer speeds.  These travel time curves started reminding me of delay calculations from queueing theory from grad school. Read more…

At the 2016 TRB Annual Meeting last month, Metro, together with DDOT and AECOM, presented the H and I Streets Bus Lanes as a case study of a bus lane in a downtown environment. TCRP Report 118 concluded that arterial bus lanes, ranging from low-cost restriping of existing lanes to new bus lanes, could offer 12-57% reliability improvements.

The presentation, built upon the 2013 study – H and I Streets Bus Improvements, highlighted the need for actions for all users and provided a range of improvement options for the H and I Streets corridor through downtown DC. We discussed details of the bus lane alternatives and benefits back in November 2013, and in the study’s final report (PDF). Here is a snapshot of the alternatives considered in the study:

Summary of Alternatives, click for a larger version.

The TRB session participants were interested in the status of the study recommendations, and raised a big question on how to solve bus delays in a large downtown area including river crossings.  The good news is that DDOT is including the bus lane alternatives in a new study — more details soon — that aims to improve the urban design and enhance the streetscape along Pennsylvania Avenue between 17^th St. NW and Washington Circle.  The DDOT study intends to assess the operational feasibility of the contra-flow bus lane on H Street – the best performing bus lane alternative in the 2013 study. This study will be initiated in 2016.

Stay tuned.

Update, 2/25/2016:  The paper has been accepted for publication in the Transportation Research Record, Journal of the Transportation Research Board.