Wednesday, March 9, 2016

Do buses have to be slow?

There are many reasons why buses are frequently regarded as the last resort when it comes to mobility options and choices. Speed or the lack thereof is one of them. There are as many reasons why city buses have a hard time breaking the speed barrier of, say, 12mph. Chief among them is that buses stop a lot to take on passengers or to let them off.

A bus system without riders would clearly be faster. Well, silly as it sounds, that gets to the crux of the matter: what is the optimal intersection between convenience (the bus stops right where you live, work or otherwise want to go) and expediency (once you are on the bus, you want it to go without stopping until it arrives at your destination).
Riders slow down the bus

Clearly, anything that makes the bus quicker without taking away convenience would take the cake. 

What are the chief slow downs for buses that are not related to the convenience of riders?

Or,  to put it more appropriately, what is slowing the trip without adding any benefit to the rider? Bus speed isn't everything. A long walk to and from the bus stop, a transfer without a prompt connection, buses that pass by because they are full, those things don't relate to the speed of the bus but they are equally annoying and slow the overall trip.
So for a shorter overall trip one has to look at bus speed and everything else on the trip that doesn't take place on the bus.

The main impediments to bus speed:

- Being stuck in traffic. If the bus sits in a platoon of cars transit riders and cars drivers are equally slowed but transit riders don't have the convenience of the car drivers to eat, listen to music, have privacy and plenty of space to stretch out, instead they may hang on a strap squeezed into a tight spot but don't get any privilege for doing the environmentally friendly thing. Urban transportation policy should change that
Stuck in traffic or at red lights, a common occurrence
- Being stuck at a stop for a long time because a dozen people crowd the front door sorting through fare-cards and cash or because the bus is crowded and nobody wants to make room for those who still want to board 

- Sitting at a red light that doesn't change, especially annoying if hardly anyone gets to use the green cycle but an obstacle for fast transit even if there is a lot of cross traffic.

- a faster bus being trapped behind a slower bus which is loading a wheelchair rider or otherwise slowed down but there is no way to move around because the bus stop is too short or too crowded with buses

The main reasons for long trip times:

- The bus is late (worse: It doesn't show up at all)
- The bus doesn't stop because it is already full.
- To complete the trip one has to wait for a connecting bus which is late, or full
- The stop is far from the origin or the destination

Time , as we all know, doesn't flow evenly. Nothing makes it pass slower than standing still while waiting for a bus while the clock is ticking away, no matter what the reason.

The best solutions to these impediments  vary from case to case, and sometimes are even at odds with each other as already noted. It requires real data to find out which one of these factors contributes to the overall trip time the most. Without exact data it is easy to throw resources at the wrong solution. Still, but a number of candidates for potentially being good solutions come to mind:
Dedicated bus lane on Lombard Street

The best way of combating as bus being stuck in traffic are exclusive bus lanes that allow the bus to proceed no matter how congested the other lanes are. This is cool where there is extra space to mark such a lane off but not feasible if there is only one lane to begin with or two which are already crowded or if much cherished parking has to be taken away, or a bike lane. 

To give lanes to buses requires courage by those who control the road space. In Baltimore that's the City, not MTA. And even after those lanes are created (like on Lombard Street) they are not very effective without enforcement. Related to bus lanes is another tool of getting buses moving on congested roadways is signal priority (TSP). It could mean giving a bus arriving at a signal on its own lane a green light sooner or keeping it green longer, but it can also work when there is no extra lane: As soon as a signal detects a bus in the waiting queue the signal starts waiving everybody through until the bus passed the light. For this to work well, stops must be placed right after a signal not before, otherwise the extra green time would be wasted. For TSP to work signals and buses need hardware and software that can speak to each other, in other words, it costs a lot of money to do this on the large amount of signals a city has on the major bus routes.

Both solutions so far are depending on collaboration between transit the agency and street space administrators (in a region that would be several agencies). 

The obvious way to combat full buses is to run more of them (expensive) or bigger ones (articulated buses, for example), but there are other solutions that are more complicated, such as making sure the buses follow the schedule because nothing crowds a bus more than a long gap in service because a bus is late. It doesn't help then, if two more follow right behind.

A solution that a transit agency can pull off on its own is to accelerate the bus boarding by allowing only prepaid boarding like on the light rail trains. Since those ticket machines are too expensive to be placed on all bus stops, those Charm Cards or other pre-paid tickets would need to be sold or re-charged in stores all over the transit service area. The amounts to be pre-paid need to be small since many people can't afford to load a card up with $20 in one setting as it is done with the EZ passes. Once a transit system would only allow prepayment (as is the case already in many cities), passengers could board through the front and the rear doors. Some transit agencies even bought standard length buses with more than two doors. Of course, a free system like the Circulator also has pretty quick boarding except when the driver is asked for directions. 

For a long time it was a credo among transit operators that a "one seat bus trip" is preferable over one with transfers because it obviously avoids the wait between buses. But here, too, the devil is in the detail. One seat trips tend to entail long routes and that in turn makes delays more likely or schedule adherence more difficult. Buses start to bunch and one gets a cascading negative feedback loop resulting in a longer trip instead of a shorter one.

transit first 

the science of bus bunching
Another expediter is the unbundling of buses vying for the same curb space. If a stop is served by just one or two lines, it won't happen as much that riders wait in the wrong spot, that a bus is trapped behind another that can't pull out or that stops are so crowded that it takes a while before would-be riders show up at the bus door. 

Finally, the biggest expediter of trips may be frequent buses. A schedule with buses coming every 10 minutes or less (headway) allows riders to leave work or the home when they actually want to and not when the bus schedule requires them to, provided the buses adhere to the headway spacing and are not all coming bunched in one heap. The wait at the stop will be shorter and a missed bus doesn't mean immediately that the whole day has to be reconfigured. So even if a bus still travels with only 12 miles an hour, it likely shortens the trip on the front end. And even if doesn't shave off actual minutes, it creates a perception of being faster and certainly more convenient because riders count time differently, depending on whether they are on the bus or off the bus. As already noted, time waiting for a bus counts double! 
High frequency network

This is why the idea high-frequency bus service has become recently popular. A frequent bus is less likely to be late because it will be less likely to be crowded, it reduces the anxiety of missing one and is much more likely to considered a viable travel option.

Watch high-frequency bus systems being implemented in cities across North America. The Baltimore region in a collaboration between City, MTA and the regional BMC is working on it.

Klaus Philipsen, FAIA
  





Three door bus (VanHool)
all door boarding test in LA