ALEXANDER DENNIS INC. Download PDF Report
Alexander Dennis Inc. submitted a model Enviro 500, diesel-powered 82 seat (including the driver) 39-foot bus, for a 12 yr/500,000 mile STURAA test. Testing started on February 1, 2005 and was completed on August 25, 2005. The Check-In section of the report provides a description of the bus and specifies its major components.
The primary part of the test program is the Structural Durability Test, which also provides the information for the Maintainability and Reliability results. The Structural Durability Test was started on March 3, 2005 and was completed on August 22, 2005.
The interior of the bus is configured with seating for 82 passengers including the driver. Free floor space will accommodate 40 standing passengers resulting in a potential capacity of 122 persons. At 150 lbs per person, this load results in a measured gross vehicle weight of 54,670 lbs. In order to avoid exceeding the GAWR of all three axles, ballast for 26 standing passengers was eliminated. This reduction from full capacity resulted in an adjusted measured gross vehicle weight of 50,980 lbs and was used for all dynamic testing. The middle segment was performed at a SLW of 48,890 lbs and the final segment was performed at a CW of 36,560 lbs. Durability driving resulted in unscheduled maintenance and failures that involved a variety of subsystems. A description of failures and a complete and detailed listing of scheduled and unscheduled maintenance are provided in the Maintainability section of this report.
Accessibility, in general, was adequate, components covered in Section 1.3 (Repair and/or Replacement of Selected Subsystems) along with all other components encountered during testing, were found to be readily accessible and no restrictions were noted.
The Reliability section compiles failures that occurred during Structural Durability Testing. Breakdowns are classified according to subsystems. The data in this section are arranged so that those subsystems with more frequent problems are apparent. The problems are also listed by class as defined in Section 2. The test bus encountered no Class 1 or Class 2 failures. Of the 80 reported failures, 53 were Class 3 and 27 were Class 4.
The Safety Test, (a double-lane change, obstacle avoidance test) was safely performed in both right-hand and left-hand directions up to a maximum test speed of 45 mph. The performance of the bus is illustrated by a speed vs. time plot. Acceleration and gradeability test data are provided in Section 4, Performance. The average time to obtain 50 mph was 43.62 seconds.
The Shakedown Test produced a maximum final loaded deflection of 0.102 inches with a permanent set ranging between -0.002 to 0.004 inches under a distributed static load of 45,750 lbs. The Distortion Test was completed with all subsystems, doors and escape mechanisms operating properly. No water leakage was observed throughout the test. All subsystems operated properly.
The Static Towing Test was performed using a target load (towing force) of 43,872 lbs. All four front pulls and all four rear pulls were completed to the full test load with no damage or deformation observed. The Dynamic Towing Test was performed by means of a front-flat tow. The towing interface was accomplished by incorporating the manufacturer supplied towing apparatus. The bus was towed without incident and no damage resulted from the test. The manufacturer does not recommend towing the bus from the rear; therefore, a rear test was not performed. The Jacking and Hoisting Tests were also performed without incident. The bus was found to be stable on the jack stands, and the minimum jacking clearance observed with a tire deflated was 4.0 inches.
A Fuel Economy Test was run on simulated central business district, arterial, and commuter courses. The results were 2.26 mpg, 2.55 mpg, and 4.59 mpg respectively; with an overall average of 2.75 mpg.
A series of Interior and Exterior Noise Tests was performed. These data are listed in Section 7.1 and 7.2 respectively.