High-Capacity Buses - Articulated or Double-Decker?

A Muni articulated bus operating Route 38 Geary boards passengers on its namesake street in San Francisco. Muni operates regular buses, articulated buses, trolley buses, and streetcars. Christopher MacKechnie

High-Capacity Buses – Articulated or Double-Decker?

One of the decisions that transit agencies have to make when deciding what kind of buses to purchase is the size . While standard size buses, which usually seat thirty-eight with a further nineteen places available for standees under normal conditions, are more than sufficient for most urban transit applications in the United States in a few cases more capacity than provided by standard size buses are required.

Additional capacity when high load factors require it can be provided by either articulated or double-decker buses. Of course, additional capacity could also be provided by operating buses more frequently – a better choice for the passenger than bigger buses operated less often but difficult to achieve in the chronically dire financial conditions most transit agencies find themselves in. Assuming improved frequency is not an option, are articulated or double-decker buses a better choice to offer higher capacity?

Articulated buses are most often sixty feet long, although sixty-five feet and even longer versions have been tried in some areas. Articulated buses, called “bendy” buses in the United Kingdom, consist of almost always two sections, a front section with two axles and a back section with one axle, connected by a flexible joint. Double-decker buses are standard forty-foot buses with a second row added.

Use of Articulated Buses in the United Kingdom

While articulated buses are becoming more common in the United Kingdom, double-decker buses are still more common. It is interesting to note that articulated buses were prohibited in Great Britain until 1980.

Use of Double-Decker Buses in the United States

Historically, the use of double-decker buses in the United States has been restricted to tourist uses in places such as Los Angeles. However, beginning in the late 2000s the use of double-decker buses has increased, with a large deployment in Las Vegas as well as smaller contingents in suburban Seattle (Snohomish County’s Community Transit) and Victoria, BC. Intercity trips operated by Megabus also use articulated buses.

Why haven’t double-decker buses been used more in the United States? First, none are currently made in the United States. Transit agencies using federal money to buy buses, which most do, must comply with the Buy America Act. It would take a significant order to entice a manufacturer to do so. Second, maintenance facilities and garages would have to be completely rebuilt – an enormous expense that would only be justified if double-decker buses were clearly superior to articulated buses. As the following section describes, this is not the case. Third, low overhangs and traffic signals make double-decker buses difficult to use in the United States. Occasionally double-decker buses hit overpasses with tragic results.

Which Type of Bus is Better?

Articulated buses generally have several advantages over double-decker buses, which helps to explain why they have become more common in the United Kingdom, Ireland, and other areas which traditionally have been dominated by the double-decker.

The main one is capacity – the combination of the room taken up by the stairs in a double-decker and the lack of headroom preventing standees on the upper deck means that articulated buses can hold about 50% more people than double-deckers (at a capacity extreme, 120 versus 80). Another advantage is that articulated buses avoid the safety problems associated with people climbing the stairs of the double-decker bus while the vehicle is in motion. Articulated buses can board faster because they can have more and wider doors, have a better turning radius, and generally better fuel economy due to their lower center of gravity. Finally, articulated buses provide much better accessibility for the elderly and disabled because low-floor double-decker buses have very little room on the first level due to the staircase and the wheel wells.

Of course, articulated buses need more curb space due to their longer length.

Those above criteria make articulated buses the optimum choice for bus rapid transit . In addition, assuming adequate engine power articulated buses tend to be operated at a higher rate of speed. It is possible that drivers feel more secure driving articulated buses at higher speed because they feel more stable.

Overall

Overall, while double-decker buses have an obvious touristy-feel articulated buses are a better choice for high-capacity transit due to the reasons above.