Do TheBus’s long headways and indirect routes reduce ridership?

This post is part of an ongoing series about how Prince George’s County could improve TheBus, its public bus system. You can read the previous post here.

Prince George's TheBus has low ridership compared to other local bus networks in the region. Part of the reason is low-quality service, including infrequent buses and indirect routes that significantly lengthen trips for riders.

Short headways significantly increase the quality of bus service

If Prince George's County wants to increase ridership on TheBus, providing better service is essential. After longer hours of operation, the most common service improvement riders want is for buses to come more frequently.

However, providing more frequency is expensive. For a bus system, costs scale with the number of buses and the number of hours they're in operation — so doubling a route's frequency can also double the cost of operating it. However, reducing the headway, or the maximum time passengers have to wait between buses, makes transit much more useful for passengers and in turn, more people tend to ride.

Rapid transit systems like Metro usually aim for headways of 10-12 minutes or less. That's short enough that passengers can go to a station without worrying about the schedule and expect a train to arrive shortly. High ridership bus lines in most cities usually aim for similar headways for the same reason.

While TheBus's routes (with the possible exception of the 17) don't serve the sort of core lines that would likely justify such short headways, a number of TheBus routes would benefit from having buses come much more frequently than they do today.

Since TheBus doesn't provide evening or weekend service, headway at mid-day on weekdays is a good guide to the minimum frequency provided on each route. While higher frequencies at rush hour may make sense, they're also expensive to provide. Buses and drivers that run the extra rush-hour runs will be idle at midday.

Many high-ridership lines have unacceptably long headways

Ideally, the routes with the highest ridership would also be those with the shortest headways. It makes sense to devote limited resources to improving frequency on high-ridership routes first because this will benefit the most passengers, and these routes are more likely to be overcrowded.

Frequency and Ridership of TheBus Routes

TheBus Route	Feb 2018 Daily Ridership	Mid-day Headway		TheBus Route	Feb 2018 Daily Ridership	Mid-day Headway
Route 32	806	30 min		Route 34	340	15 min
Route 18	781	80 min		Route 26	317	45 min
Route 16	718	60 min		Route 23	274	~30 min
Route 51	711	10 min		Route 13	261	40 min
Route 20	668	60 min		Route 15X	206	no service
Route 24	661	30 min		Route 22	202	40 min
Route 21X	655	20 min		Route 12	186	60 min
Route 21	456	66 min		Route 36	168	45 min
Route 17	443	30 min		Route 27	168	30 min
Route 30	431	50 min		Route 37	160	no service
Route 33	408	40 min		Route 28	146	45 min
Route 35	386	~30 min		Route 25	126	70 min
Route 11	355	30 min		Route 53	28	50 min
Route 14	344	45 min		Route 35S	31	no service

However, no such pattern is apparent when one compares ridership to mid-day headway for TheBus routes. The busiest route, the 32, has a mid-day headway of 30 minutes, but the next-busiest routes, the 18 and 16, have headways of 80 and 60 minutes respectively.

While a bus with a mid-day headway of 30 minutes is relatively convenient for shopping trips and getting to work — a rider will want a schedule, but can reasonably plan around departure times — a bus that comes every 80 minutes can force passengers to waste a substantial part of their day, especially if the timing of the route doesn't line up with when they get on or off of work or need to be at a doctor's appointment.

Continuing down the list of routes in order of decreasing ridership, the mid-day frequencies of routes seems to vary, largely at random, between 30 minutes and about an hour. Buses come every hour or less frequently on many of the system's higher-ridership routes, which is a serious problem. After increasing the system's hours of operation to include evening and weekend service, the next priority for TheBus should be reducing mid-day headways on its highest-ridership routes to 30 minutes.

An additional issue is that many routes have headways that are numerically odd — 66 or 70 minutes, for example — making it nearly impossible to memorize the route's schedule. Where possible, these headways should be reduced to a more regular interval and repeat at regular times after or before the hour.

Direct bus routes generally provide faster service, but they aren't always practical

In dense cities with regular grid systems, bus routes are usually designed to run in relatively straight lines so that they connect their destinations as quickly and directly as possible. If the city is dense enough to support parallel bus lines every half mile or so, every destination will be within walking distance of a bus stop and riders shouldn't need more than one transfer to reach their destination.

Unfortunately, in a suburban environment such as much of Prince George's County, this sort of bus grid isn't a viable option. Density, and thus ridership, is lower, which means that some areas don't have bus service, and routes often need to detour to serve pockets of density and major destinations. This is made worse by a suburban built environment where major destinations are often located some distance off of major roads.

Unlike in Montgomery County, Metro stations in Prince George's County tend to be located far from major thoroughfares. That's a particular problem for TheBus, since its routes are generally designed to get passengers to and from Metro stations, where they can transfer to trains and other bus routes.

The street grid in certain parts of Prince George's County, particularly around Largo where many county offices and Prince George's Community College are located, makes this problem even worse because there often is no direct route between two points. Even major roads often end in culs-de-sac.

Many of TheBus routes are quite indirect

Given the constraints TheBus operates under, most — but not all — of its routes are reasonably direct. To quantify the directness of TheBus routes (excluding small-area circulators, like the 51) I used the online tool Gmap Pedometer to measure their lengths as well as the straight-line distance between their endpoints.

I then divided the route length by the straight-line distance to produce a measurement of circuitousness: a value of 1 means that the bus route is perfectly straight, while higher values mean it travels further out of its way.

The Most Circuitous TheBus Routes

TheBus Route	Region of County	Daily Ridership	Route Length	Straight-Line Distance	Ratio of Route Length to Distance
Route 26	Central	317	10.1 mi	1.4	7.2
Route 24	Central	661	13.5 mi	2.5	5.4
Route 28	Central	146	8.1 mi	1.6	5.1
Route 14	North	344	8.3	1.7	4.9
Route 23	Central	274	11.5	2.5	4.6
Route 22	Central	202	7.2	2.2	3.3
Route 35	South	386	14.4	4.5	3.2

Using this measurement, I found seven TheBus routes with circuitousness values greater than 3. Unsurprisingly, given that that area has particularly disconnected street grids, five of them, the 26, 24, 28, 23, and 22, were in the central portion of the county, between US-50 and Pennsylvania Avenue. The other two, the 14 and the 35, are located north of US-50 and south of Pennsylvania Avenue, respectively.

Not all indirect routes are necessarily bad, but some have serious problems

The 24, one of the most heavily-ridden routes in the system, does quite poorly by this metric. However, like the 14, 23, and 26, it's a U-shaped route with both ends anchored by Metro stations. While the route does not run directly end-to-end, most passengers will have a relatively direct route to a Metro station. Except for the 23 which serves Cheverly and Addison Road, each of these routes connects to two stations on the same line, making it unlikely that many passengers would travel the full length of the route.

The non-direct routes taken by the 22 and 28 are more problematic.

The 22, which serves the area east and north of the Morgan Boulevard Metro station, is constrained by a poorly-connected road network that forces it into spiral-curled route. The combination of the spiral route and the fact that the 22 backtracks several times to serve destinations far from its route make it an indirect and inconvenient service.

Similarly, the 28 has a number of backtracking sections and does not provide a direct ride from most places it serves en route to the Largo Town Center Metro station at its southern end. However, it is somewhat less constrained by the street grid, and its issues seem to be more due to a desire to serve more destinations with one route than is really viable.

The 35 is actually less of a problem than it looks at first glance, which likely explains why it has the second-highest ridership of the apparently-circuitous routes. It provides a very indirect connection between the Camp Springs area and the Southern Avenue Metro Station, but other routes, including the 32 and 33, connect these areas more directly.

The 35 is better understood as connecting the Camp Springs area to National Harbor and northern portion of Oxon Hill Road, while also connecting those areas to Metro. Like the U-shaped routes mentioned above, few passengers are likely to want to ride the full length of the route, and it provides relatively direct trips for passengers on each half of its route.

One-way loops create significant inconveniences for riders

Route 12, the lowest-ridership route in the northern part of the county, poses a different sort of problem. Although the route serves a quite-dense area of the county, it does so in an ineffective way. Most of the length of the route is a one-way loop between Queen's Chapel Road and Rhode Island Avenue, although there is also a two-way section between the West Hyattsville Metro station and Sargent Road in Chillum.

The Chillum portion of the 12 is reasonably direct, given the constraints of the local road grid. The roughly two-thirds of the route southeast of Queens Chapel Road, however, operates as a one-way loop, meaning that passengers from much of this route have to make either their inbound or outbound trip by going around the loop the long way. Providing bidirectional service on the route or else restructuring it is a must if the southeastern portion of the 12 is to provide effective service.

It is still possible to submit your comments on how transportation could be improved in Prince George’s County. In upcoming posts, we will share more ideas for how to improve TheBus.