Cantrell Rail Services, Inc.
Addressing Track Modulus at Bridge / Track Transition Zones
Two main problems have existed for years in the railroad industry. The low bridge ends have been causing damage to the bridges and causing damage to bridge ends. Both of these have been a severe maintenance issue. For years the railway engineering departments have been trying to match the Vertical Track Modulus at these locations. They have used 9 -10 foot transition ties between concrete or regular woos tie tracks. Thus normally the transition area becomes extremely muddy. The purpose of this paper is to show how different plates on the bridge can reduce the impact loading on the bridge. Transitioning off the rigid bridge structure onto the bridge end causes excessive loading of the sub-grade. When the bridge ends are low and the train goes onto the bridge, the impact loading is severe, causing damage to the bridge and the supports under the bridge. ( Not only damaging the Bridge but is damaging the rail with impact and sets up a lateral loading that not only damages the rail but also the locomotive wheels. And it eventually does damage to the car wheels.) The vertical track modulus on the bridge is 12,000 to 13,000 psi and the vertical track modulus is 3500 to 7000 psi on wood or concrete tie tracks. The paper will look at different transitions on the bridge ends, not only on concrete and steel open deck structures but also on concrete ballast deck. On concrete tie tracks, we have used the wood transition ties for a considerable length of time. This paper will show that when this happens, it sets up three different transitions in approximately 40 to 50 feet. When this occurs, there are severe maintenance issues and drainage problems as a result. The paper also emphasizes the importance of determining the cause of the maintenance problems in order to apply the proper solutions. The paper will also explain lateral and vertical loading on the bridge.