Busses, shuttles, and similar specialty vehicles are designed to fill sometimes very large public transportation contracts. Because of this, safety and durability are paramount – and all commercial vehicles must meet stringent federal transportation standards. For vehicles purchased with federal funds, there is an added step. Prior to FTA approval, busses and similar public transportation vehicles must demonstrate that they can meet the structural integrity and durability standards of the Altoona proving grounds.
As with most proving grounds, there are set costs associated with facility usage, fuel, and the driver. For this type of testing, the manufacturer is typically asked to deposit a significant percentage of the cost upfront prior to any testing.
In addition to forfeiting these expenses, failure to pass the endurance test of the Altoona track generally means time-consuming and costly design changes. So naturally, vehicle manufacturers want to arrive at the proving grounds confident that certification is a mere formality.
ARBOC
With more than 4,500 buses in service, Middlebury, Indiana’s ARBOC Specialty Vehicles leads the low-floor cutaway bus market providing unsurpassed passenger accessibility and comfort over traditional high-floor cutaway vehicles. ARBOC also offers a medium-duty bus for transit and shuttle applications.
With a contract for a fleet of shuttles on the line, the manufacturer needed to demonstrate Altoona durability compliance. To better ensure that a new design would pass these testing standards, Six DoF Testing & Analysis (6D) was commissioned to help validate the new bus design.
The 6D Process
Together with its strategic partners, InDepth Engineering Solutions and Navistar Proving Grounds, 6D provides specialty vehicle manufacturers with more confidence that their vehicles will achieve FTA/Altoona certification. 6D combines field testing with analytical simulation to provide a low-cost solution for predicting vehicle survival relative to the required number of Altoona track durability miles. As an initial step, InDepth Engineering Solutions provides the analytical modeling to help determine where strain gauges and accelerometers are to be placed on the vehicle structure. 6D then instruments the vehicle and prepares it for testing.
Because Navistar maintains a course similar to that at Altoona, tests are performed on the company’s proving grounds. As the vehicle is driven a handful of laps (generally 2-3) around the course, data is collected, analyzed, and correlated to Altoona durability events.
6D analyzes the data to predict fatigue life at the measurement locations. Customers are provided with a report estimating how many miles into the Altoona qualifier the manufacturer can expect to see a failure. Now, in just fraction of the time and expense manufacturers can predetermine a vehicle’s expected success rate for Altoona compliance.
Improving Success Rates
Armed with this information, leading vehicle manufacturers like ARBOC can make any needed design changes or adjustments prior to committing designs and costs to Altoona testing.