Too many stops or not enough?

September 10th, 2013

Chart of the relation between the number of stops on a transit line and it's so-called access

Access is a pretty vague word. I don’t think I could succinctly define it and I suspect no one else could either as it regards discussions about transit and transportation. Still, we can imagine a transit line that makes no stops at all and say that it would provide no access whatsoever. It would be useless. Similarly, a line with infinite stops where the bus moves infinitesimally after each stop before stopping again also has an access value of 0; it would also be useless.1

Somewhere in the middle is the Goldilocks stop spacing arrangement. Where does the m+ fall on this spectrum? Where do the other lines in the system? Might there be an ideal middle ground or are both either too crowded or sparse? Is there room for …lets call it ‘schedule diversity’ within a corridor? What effect does that have on effective frequency and average wait times at the skipped-over stops?

I’d like to hear SORTA’s and TANK’s official positions, or perhaps not positions but perspectives, on these questions as they move forward with their discussions of adding more rapid-transit-like lines to their systems. It’s not evident to me as an outsider that they’ve weighed the issue at all, at least publicly. Transit planners? Can you weigh in please? I’ve made my opinion clear in the above chart but I’m curious how SORTA and TANK would re-draw it and what they might add to it.

Show 1 footnote

  1. Though my line tapers off here without hitting 0 because the driver has some agency in stopping and doesn’t have to stop at an empty stop. Infinite stops might be more comparable to dial-a-ride or flexible schedule or no-stop services.

9 responses to “Too many stops or not enough?”

  1. It really just depends on what you’re trying to accomplish. Sometimes moving people as quickly as possible is not the desired goal, but sometimes it is. In the case of either bus or rail one has to understand what the problem is first before prescribing the solution.

    In most cases I do think that buses stop too frequently, but as a daily bus rider I also know that I value the opportunity to be able to ride the bus at least one or two blocks closer to my destination. I know this is selfish, but I don’t think it’s uncommon. It’s particularly beneficial to the rider when there is inclimate weather or the rider has items they are carrying around.

    I think the new Metro*Plus service to Kenwood shows that much fewer stops are reasonable. I guess we will see how ridership is for that route over the long haul, but it is essentially the same bus service but with fewer stops. It certainly is not anything close to BRT.

    But I think the bottom line is that there is no one clear answer to your question. While each line fits within an overall system, it is also meant to accomplish unique goals relevant to that corridor/route.

    • Nate Wessel says:

      How might you best be convinced, thinking of yourself as a rider rather than an objective judge of the system, that stop consolidation could improve your access assuming it could in a given situation?

      I agree that stop proximity is a psychologically compelling way of assessing access for the average rider. I know it is for me. But I’m interested in balancing that with an equally compelling way of understanding the benefits brought by a more limited-stop, higher-speed service like the m+.

      Isochrone maps? A prosaic description of newly accessible places? A decreasingly complex route map?



  2. Tim Bender says:

    What people perceive as a “reasonable” maximum walking distance and what they tolerate in reality are completely different, and there is much research that supports this. When TANK modified the alignment of the Southbank Shuttle in the CBD public outcry was approaching hysteria. TANK went with their gut anyways, asking everyone to walk just 1 or 2 blocks further to get to the bus (along with several other key changes to the service) and now that service is amazing; ridership gains are exceeding everyone’s expectations.

    I loved the M+ service in concept; limited stops along one of Metro’s slowest, longest and most intolerable corridors. Yet when I look at the public schedule it’s only saving like 15 minutes off the one-way cycle time during rush hour. That’s not improving “access” if you ask me.

    • Nate Wessel says:

      I’m now curious how much time could be taken off the m+’s trip by not stopping at all. What’s the floor? What’s the floor assuming we might eventually get signal priority or a path above, below, or around car traffic?

  3. Nate Wessel says:

    Thanks for your comments guys! :-)
    I’m working on an abstract for a paper/poster I’d like to do on this topic for the next TRB conference and this is all quite helpful.

  4. James Braye says:

    Hi Nate, UC student, long time lurker. I’m always interested in transit and infrastructure!

    Any intention of plotting m+ ridership growth over time and/or doing analysis of ridership affects for the routes that the m+ overlaps? I understand that it’s a new service, but I think that would be some really interesting information! The 4-5 times I’ve used it, the buses have been at ~ 30-40% full from the Gov square to McMillan.

    As for “schedule diversity”, I care most about frequency. As a student, I can typically work on the bus. I often ride the 31 from around USquare to UC Victory Parkway campus to study and grab some McD’s. I suspect my ridership habits would not be changed by having an express 31, but I would be peeved to see SORTA resources being spent on bunched buses with irregular headways (m+ buses have been bunched to each other and the 17/19 that runs a lot of the same route near main campus).

    And I think that calling m+ even a “Pre-BRT” corridor is a mistake. I feel SORTA should save the term for when (if?) they can get dedicated lanes in key areas and traffic signal priority.

    • Nate Wessel says:

      I like the way you think! I have asked SORTA for more..shall we say…longitudinal passenger count data but I think they don’t know enough about databases or don’t have ready enough access to their own data which is stored in proprietary systems to be able to give it to me without unreasonably tasking themselves. Maybe an FOIA request would get them moving. I don’t know. I did also ask about the m+ specifically though as well, and the picture is a bit more complicated there because not all of those buses have been fitted with the passenger counting systems yet. At least that’s what I’m told. I was hoping for a day-do-day passenger count for the first couple of months so we could see how quickly it took off. In any case, I hope we’ll be able to glean something from the new passenger counts when they come out by comparing it to changes in it’s sibling #4. I’d expect them fairly soon. The data I have from them has been averaged over a month and it’s been almost a month since the changes took effect. I bet they’re almost ready!

      It should be noted that I say “schedule diversity” here with my tongue firmly in my cheek”–not really. I actually have no idea what the hell that expression means. But I do say it somewhat sarcastically. I’ll get to illustrating this in another post, but it should be fairly obvious when you think about it that if you take a corridor’s service(assuming operating funding stays the same) and speed up half the buses, the day’s average frequency will stay the same or may even go up a bit while the experience of the person actually waiting for a bus will be much more erratic since buses won’t even try to maintain even spacing. So when I say room for schedule diversity, what I really mean to say is room in the budget to run two high-frequency lines in a given corridor rather than the one that exists–because the frequency of the two lines split from the first will each have to increase to match the previous level of service as measured by frequency.

      Welcome to the blog! Please comment away :-) I feel like I’m just writing to myself sometimes.

      • Tim Bender says:

        Most agencies don’t have passenger counters on 100% of their fleet. They are somewhat expensive, and FTA only requires that you provide a sample of boarding/deboarding counts (search FTA Section 15 reporting requirements) not 100%. So Metro may have counters on just 20% of their fleet and dispatch makes sure those vehicles get cycled through the system on a regular basis. Thus your monthly average data.

        Additionally, as you have alluded to Nate, resources (both money and time) are limited and the value of this data is just recently being realized as important. I would suspect that in 5-10 years (a generation of this technology) you will see much better raw data and analysis.

  5. […] poster topic, and the biggest devourer of my recent time, is a quantitative analysis of total access in several stop-spacing and service frequency scenarios. It’s my intention to prove(or disprove) that people, at […]