Category Archives: Environment

Advanced hybrid buses have better fuel economy, fewer emissions

One of Metro Transit’s new advanced “super hybrid” buses—built in Minnesota and billed as the cleanest, most efficient diesel-electric hybrid buses in the United States—garnered national attention at the American Public Transportation Association’s Bus and Paratransit Conference May 5–8 in Indianapolis.

Photo of superbus
Photo: Metro Transit

Unique because of its all-electric accessory systems, the bus was featured at the event so that transit professionals from across the country could experience this new hybrid technology firsthand, says Chuck Wurzinger, assistant director of bus maintenance at Metro Transit. The bus is one of two advanced hybrids built for Metro Transit in 2012. They currently operate on local routes with frequent stops in downtown Minneapolis and its surrounding communities.

The decision to purchase the new hybrids was greatly influenced by the results of a University of Minnesota study aimed at improving fuel economy in diesel-electric hybrid buses, Wurzinger says. The “Superbus” study, led by mechanical engineering (ME) professor David Kittelson, included an energy audit of major accessory systems on a standard hybrid bus. The study was funded by Metro Transit, CTS, and the U of M’s Institute for Renewable Energy and the Environment (IREE).

Study findings indicated that up to half of the fuel consumed by hybrid buses is used to power accessory systems. According to the research team, powering these systems electrically could significantly improve fuel efficiency.

The new advanced hybrids do just that, using all-electric systems to power the heating, air conditioning, engine fans, power steering, and air compressor. These components improve fuel economy, reduce emissions, and allow the buses to be operated in electric-only mode for short periods.

Photo of Metro Transit diesel-electric bus
Photo: Metro Transit

One of the buses also has start/stop capabilities, which allow the engine to shut down at bus stops and traffic lights. “This reduces engine idle time while maintaining all other bus functions, including passenger comfort and safety features,” Wurzinger says.

Although the buses have been in service for only a short time, they are already showing promising increases in fuel economy, Wurzinger says. “We have also operated them consistently on electric power inside the bus garage, which helps keep the air clean in the building. This reduces the amount of ventilation required in cold weather, which means less energy is used to heat the building.”
Metro Transit has more than 130 hybrid buses in services--about 15% of its total fleet

Along with a standard hybrid bus and a conventional diesel transit bus, one of the advanced hybrids will be monitored and evaluated in a new study conducted by U of M researchers in collaboration with Metro Transit. The multidisciplinary research team includes Kittelson, ME associate professor Will Northrop, ME research associate Winthrop Watts, and applied economics associate professor Steven Taff.

As part of the study, funded by IREE, the team will collect real-world, on-the-road data from the three buses in all seasons on a variety of route types. The researchers then plan to compare the efficiency and emissions of the buses and make recommendations to Metro Transit about which configuration is the best for a given application. Data collected from the study will also allow Metro Transit to work with bus manufacturers to optimize bus performance.

“We believe the results will be useful in writing bus technical specifications and also in determining if a certain type of bus is best suited to a certain type of bus route,” Wurzinger says.

Ultimately, this information could be used to determine which buses to assign to which routes as well as which type of bus to purchase given fleet replacement or expansion requirements.

The project is scheduled for completion in 2015.

Reprinted from the CTS Catalyst, June 2013.

CTS Research Conference videos and presentations now available

If you weren’t able to attend the CTS Research Conference, or, if you simply want to check out presentations from other sessions, the videos of the keynote and luncheon speeches, as well as PPTs from most of the concurrent sessions, are now available on the CTS website. You won’t want to miss Minnesota Department of Health Commissioner Ehlinger’s tuneful take on the links between health and transportation and Elizabeth Deakin’s view of new ways to get around.

New video showcases Minnesota city and county stormwater management techniques

Earlier this week, the Minnesota Local Road Research Board released this new video showcasing best practices for local stormwater management. Although it’s primarily a training video for engineers and other public works professionals, non-transportation geeks might also enjoy learning about some of the interesting, innovative techniques being employed in cities and counties across the state.

Those who’d prefer not to watch the whole 14-minute video can skip ahead by clicking on these highlights:

  1. Woodbury’s stormwater ponds (1:52)
  2. Washington County’s bioretention gardens (2:56)
  3. “Green roof” bioretention method (4:02)
  4. Maplewood’s underground detention system (4:39)
  5. Greenway stormwater project in Minneapolis (6:03)
  6. Minnetonka’s hydrodynamic separator treatment system (7:47)
  7. Arden Hills’ infiltration (swales) system (8:26)
  8. Shoreview’s permeable pavements (9:52)
  9. Ramsey-Washington permeable pavement project (11:11)
  10. Tree boxes/trenches in Ramsey-Washington (12:06)

Overall, the video gives you an appreciation for the incredible amount of planning and work that goes into managing stormwater runoff — a task that’s critical to protecting the state’s waterways from pollution (but which many people no doubt take for granted). For those who want to learn more, the best management practices showcased here are examined in greater detail in a recent LRRB report, “Decision Tree for Stormwater BMPs,” which is available for free on the LRRB and MnDOT Research Sevices websites:

U of M transportation research highlights video

U of M transportation research highlights during 2012-2013 include a smartphone app for visually impaired pedestrians, pedestrian and bicyclist safety in roundabouts, methods for counting bike and pedestrian traffic on trails, and a filter that takes phosphorous out of storm water.