On Coverage vs. Expedience, or why the #24 is slow

November 7th, 2012

By looking at the routing of a transit line, one can with a little study discern the motives of it’s establishment. I’ll take SORTA’s #24 as an example. The #24 is a relatively infrequent line, but one with trips evenly spanning most of the day.

The #24

The #24 goes from Anderson Township to Downtown through Mt. Lookout, Hyde Park, Walnut Hills, and Corryville.

It travels a fairly corrugated route, going, as the crow flies, only about 9 miles but taking a full 19 miles actually on the street to do it. It takes an average total time end-to-end of about 70-80 minutes, meaning an absolute end-to-end average speed of 7.2 MPH(as the crow flies) and as it actually travels on the street, closer to 15.2 MPH.

I take the #24 as an example particularly because of it’s illustrative zigzag in Mt. Washington.

#24 in Mt. Washington

The illustrative zigzag

This deviation from Beechmont Avenue takes an additional 2.8 miles over a hypothetical course that simply follows Beechmont through Mt. Washington.

possible #24 allignment

This doesn’t actually exist.

That means it accounts for about 15% percent of the surface distance of the trip. If we assume that the vehicle’s speed is roughly constant(its not getting on the highway or flying through the air at any point), we may fairly assume that the deviation also accounts for about 15% of the trip’s total travel time, 11.3 minutes, and a decrease in potential average speed(as the crow flies) of 1.65 MPH(8.9 MPH potential vs. 7.2 MPH actual).

This feature of the routing isn’t dictated by topography, nor by the necessity of of driving a large vehicle or any other purely mechanical matter. Indeed, Beechmont just carries right on and the bus seemingly can’t make up it’s mind as to whether it prefers main roads or side streets. The reason this zigzag exists it to provide access to transit. In another post I defined ‘access’ as the end goal of mobility. I also said that mobility tends, all things being equal, to enhance access. Thus the route deviates to pass directly in front of supposedly somewhat immobile people to provide them access to mobility itself and thereby access to many other things. But all things are rarely equal.

This zigzag itself introduces significant delay into the trip of anyone not stopping on one of the streets off of Beechmont to which the line deviates. That decreases their potential for mobility by substantially reducing the real distance they can travel in a given time. It also means, in a world of limited resources, that money spent here (gas, driver wages, maintenance) isn’t spent in some other part of the transit system.

Map of the #24 showing 10 minute travel distance

Here’s how much farther you can go with an extra somewhat-less-than 10 minutes.

schedule of the #24

Numerical proof of the above

For people living off of Beechmont who do have the ability to reasonably get to Beechmont, it may significantly add to travel time as well.

The zigzag, and it’s possible absence raise the question of who the line is designed to serve. In it’s current form, the line indicates a choice for closer access to transit itself for the people south of Beechmont in Mt. Washington over the expedience of those coming from or going to Anderson Township. This indicates that SORTA sees the line as serving people to whom the challenge of getting to a stop on Beechmont is greater than the cost of their time. This could include several general categories of people. People for whom the cost of traveling to a stop is high include the disabled, the elderly or people carrying small children or heavy bags. Then there are the unemployed and unattached, for whom time is of relatively little cost.

It assumes that there are people who can’t or won’t come to a stop on Beechmont and that coming to them instead is justified. This is transit as a social service. Providing easy mobility to these groups is a legitimate public goal(as is providing food to the hungry), and one among many goals that transit should strive to serve. The #24, at least by this segment then, does not as much intend to serve people to whom time is more of a cost than somewhat of a walk.

The #24 makes another important assumption. It assumes that people live where they do and will continue to do so, even if where they live comes to have minimal direct access to transit and that such access is critically important to them. It’s perfectly plausible that if the line were moved to our hypothetical Beechmont-only route that over time people who needed very close access to transit and who nonetheless want to live in Mt. Washington would move closer to Beechmont. This would give us the best of both worlds by allowing the line to directly serve people who need access to mobility and chopping about 11 minutes off the total trip time for everyone passing through. It would do so at the cost of people who need access and live somewhat far from Beechmont; they would either have to move or suffer from more limited access. However it’s important to note that the cost of delay from deviation is an ongoing one, and the cost of inducing people to relocate would be felt only once, though surely over the course of several years.

People not as well served by the #24 include able-bodied people with jobs, families and other significant time constraints, people who would rather walk a few extra blocks than wait 11.3 more minutes. SORTA seems to have recognized and compensated for this to some extent. Running an almost parallel overall course is the 30X, a rush hour only line going(mostly) toward Downtown in the morning, away in the evening.

SORTA 30X route map

Lines like this, of which there are more than a dozen in the current system almost exclusively serve people making trips to Downtown offices in the morning and home to the suburbs in the evening. The times the 30X operates, departing between 6 and 7 AM then again between 4 and 5:50PM, make it useless for almost any other type of trip.

The 30X also operates at a significantly higher speed, bypassing much of the course of the #24(including the off-Beechmont zigzag)and completing the same end-to-end distance in 30-36 minutes, less than half of the time the #24 takes to complete the same (insert lots of qualifiers…) trip. The combination of these two lines gives us a transit corridor with quite specialized, and actually bipolar goals. On the one hand, we have a service with a fairly high speed trip between Downtown and Mt. Washington(via Beechmont) and Anderson Township that almost exclusively serves downtown workers. On the other we have a slow, meandering line between the same points that seems to want to serve many people with low time costs and high travel costs, door to door with minimal walking.

Is there some middle ground? Is there some middle transit customer? Or could both goals, access to transportation and access generally for a broader group of people be met by some other configuration of transit service? More to come! And more to come even even on the subject of the #24. We didn’t even get to the unique connection with Uptown!

Sources: SORTA’s schedules and Google Map’s little ruler tool. Please check my math!

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