Intermodal Environment Study
More than ever, shippers are interested in how to prevent damage to their products. At the same time, the shippers are looking for the most economical ways to package, load and brace shipments in order to reduce costs. Information on the railroad environment provides shippers and their suppliers information with which to make decisions in these areas. Changes in railroad equipment and operating practices over the last several years have resulted in a need for new data establish the shock and vibration environment for today's domestic intermodal service.
In order to begin addressing the need for this type of information in the area of intermodal rail shipments, the AAR Freight Claim and Damage Prevention Division undertook a study the domestic intermodal service environment.
The study was divided into three phases. In the first phase, a standard 89' TOFC flatcar was loaded with two trailers and moved in excess of 9,000 miles. The test car was placed at various locations in several dedicated intermodal trains. Mountains, rolling hills and level terrain were traversed along two transcontinental routes, one in the United States and one in Canada. In the second phase of the study, four loaded standard 40' ISO type containers were entered into dedicated intermodal trains operated in principal U. S. rail corridors. The test containers were moved in doublestack rail cars, on articulated COFC cars and on articulated TOFC cars over a total of more than 10,900 miles.
In the third and final phase of study a 45' intermodal trailer was moved over 2,600 miles of interstate highway, 1,900 miles of primary (non-interstate) highway and 400 miles of urban streets. Data was also collected for lift-on/lift-off operations at several intermodal ramps.
Throughout the study, shock and vibration data were collected on preprogrammable data recorders. Each of these recorders housed a longitudinal, vertical and lateral (triaxial) accelerometer set.
Two data recorders were installed on each test trailer or container. One of the recorders was programmed to record random data samples at specific time intervals. This provided the random vibration data for the environmental analysis.
The second data recorder was set to record only when acceleration levels exceeded a present threshold. This recorder provided shock data for each test vehicle.