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How Do Transit Agencies Decide on What Buses to Purchase, Part 1: Bus Size

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How Do Transit Agencies Decide on What Buses To Purchase?

The biggest capital expense for transit agencies is buses ( recall the difference between capital and operating funding ). As buses in the United States are expected to last at least twelve years before being replaced, poor decisions in the coach procurement process are not only costly but can doom the agency for years. Agencies make the purchasing decision based on the following factors: size, propulsion system, high or low floor, and manufacturer. Let us look at size first:

  1. Size

City buses come in a variety of sizes, from a 20 foot cutaway van used on some lightly patronized suburban routes to a new 65 foot bus that was recently given special permission to operate on Los Angeles's Metro Orange Line. Although larger buses are more expensive than smaller buses, because operator salaries make up the overwhelming majority of operating expenses for transit agencies there is no, contrary to popular opinion, savings to operate smaller buses.

Most transit buses purchased today are of the standard forty foot variety. In some circumstances both smaller and larger size buses are purchased.

When to Buy A Smaller Bus

Certain agencies, particularly ones in smaller urban areas, often buy smaller buses. Here are some factors that may allow the usage of smaller buses:

When Light Demand Allows It

Smaller buses, which are usually thirty or thirty-five feet in length, can be bought if the transit agency expects them to be able to meet the ridership demand at the standard agency headway (usually thirty or sixty minutes with these kinds of routes). However, if the agency miscalculates the demand or if the demand increases, then service will have to be increased beyond what would be required if a larger vehicle were used in order to provide enough capacity. Of course, being forced to add additional buses increases agency cost.

When the Route Traverses Narrow Streets or Parking Lots

Smaller buses also need to be used on routes that traverse streets that are too small to be used by larger buses. In cities that have neighborhoods that have a lot of narrow streets, smaller buses can provide deeper neighborhood penetration and thus better service coverage, since larger buses would have to remain on the nearest arterial.

When Using Larger Buses May Provoke Community Opposition

Smaller buses also are generally preferred by residents, and are used in some areas where larger buses may provoke opposition. Translink, in Vancouver, B.C., has in recent years converted many conventional bus routes into what it calls "Community Shuttles". Community Shuttles generally follow the same routes as the large buses they replaced, although in some cases their small size allows them to deviate into parking lots. The operation of Community Shuttles has been received with strong approval from the community, and has generated increased ridership to the point where on at least one route conventional buses had to replace the Community Shuttles because of capacity problems.

When to Buy A Larger Bus

Transit agencies looking to purchase larger buses can choose from 60 foot articulated buses (the buses with what looks like an accordion in the middle) or double-decker buses (currently used in Las Vegas, Community Transit in Washington, Victoria, B.C., and GO Transit in suburban Toronto in North America). As mentioned earlier, Los Angeles Metro is testing a 65 foot bus, but had to get a special waiver from the California Highway Patrol since they are technically illegal in the state.

When Demand Is Too Great To Be Satisfied With a Regular Bus

The usual reason to operate larger buses is when passenger demand is too great to be served with regular size buses at a given policy headway. Instead of operating regular size buses more frequently, many transit systems have discovered the financial advantage of operating an articulated bus instead, as an articulated bus offers 50% more capacity than a regular bus while still employing only one person.

Unfortunately, several transit agencies that routinely use large buses do so on routes that do not operate particularly frequency. Since one articulated bus has the capacity of 1.5 regular buses, an articulated bus route that operates every 30 minutes provides as much capacity as a regular bus that operates every 20 minutes. Indeed, the aforementioned transit agencies have many routes that are operate with large buses and only operate every 30 minutes. But from a passenger perspective, obviously a service that operated every 20 minutes with conventional buses would be better than one operated every 30 minutes with an articulated bus, as the wait time is much less in the first case.

Special Issues With Larger Buses

Larger buses have some special issues that do not come up with smaller vehicles. For example, they need more space, both at bus stops and in the garage, than smaller buses. Converting a route to articulated buses may require the red curb at bus stops to be lengthened to allow the bus to stop safely, garage equipment may need to be replaced, and parking areas may need to be expanded to allow enough space for these new larger buses to park. Issues specific to double deck buses including making sure that all traffic lights, bridges, and other obstructions are far enough off the ground to allow the bus to pass by. Double deck buses may also result in more passenger injuries, especially on the stairwell, and often have limited space on the first floor for senior and disabled people.

Conclusion

Most transit agencies purchase standard 40 foot coaches. However, in certain instances, when a particular route has light demand, travels through narrow streets and parking lots, or operates in a politically sensitive area smaller buses are justified. In instances when demand is very high, larger buses provide more capacity without the expense of an additional operator, but transit agencies need to be careful that they do not use articulated buses as an excuse to provide poor service. Next, we will look at what kind of propulsion systems are available in today's buses and how agencies decide which one to purchase .

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