Transportation Research Record: Journal of the Transportation Research Board, No. 1863, TRB, National Research Council, Washington, D.C., 2004, pp. 61–67. 61 Presented are the results of Phase I of an FRA-sponsored study on low- cost means to increase safe speeds through turnouts by way of a retrofit or upgrade. Turnout lead length and frog angle were considered fixed, eliminating costs in relocating the frog or switch points. After in-depth research and dynamic simulation testing, it was determined that the best approach was to optimize existing American Railway Engineering and Maintenance of Way Association (AREMA) turnout geometry. This required a new diverging switch rail and reshaping both the curved stock and closure rails. This low-cost modification applies to most existing turnouts and is expected to improve ride quality and decrease wear with- out detriment to current maintenance practices. The optimization of a conventional AREMA #20 turnout with straight switch points is dis- cussed as an example. The best vehicle performance in simulations was achieved by a design having a very low entry angle. Vehicle behavior at a speed of 51 mph was significantly improved over the AREMA straight point design at its speed limit of 36 mph, as well as that of the AREMA curved point design at its limit of 50 mph. Also, simulated vehicle per- formance was nearly as good as for a #20 tangential turnout that has a 20 ft longer lead length. Finally, there was improved performance at speeds as high as 60 mph without exceeding any established safety lim- its. From these results, a turnout with the reshaped geometry has been constructed and is scheduled for installation on New Jersey Transit. Turnouts are discontinuities in the track structure, necessitated by the physical requirements for moving a rail vehicle from one track to another. In traversing a turnout, railroad wheels and flanges must travel across a running rail in either the straight or diverging direc- tion. The discontinuities necessary to allow this to happen can cause derailments due to abrupt or nonuniform changes in track geometry, which can produce excessive force levels. These discontinuities also frequently create a need for speed restrictions. The highest diverg- ing speed permitted on turnouts of conventional design in North America is generally 45 mph. To obtain a higher diverging speed, it is usually necessary to completely replace an existing turnout with a new one. Doing so can be extremely costly. There have been many attempts at improving turnout design (1–8). However, new turnout designs (such as tangential geometry points or swing-nose frogs) are generally incompatible with con- ventional American Railway Engineering and Maintenance of Way Association (AREMA) designs. This is especially significant because many turnouts are never completely replaced. There are about 280,000 turnouts on freight railroads in North America, of which only about 25% are ever replaced in their entirety. That number translates into only about 1,750 turnouts per year, assuming an aver- age life of 40 years. The balance of turnout replacement is under- taken component by component, and secondhand materials are often used in yard and branch line turnouts. This means that however superior a new turnout design might be, if it is incompatible with the existing turnout population, it will spread only slowly through the railroad network, and it will never encompass more than 25% of total turnouts. Further, while many new designs offer significantly better performance than does that of conventional AREMA standard turnouts, a substantial investment is required to take advantage of this improved performance. In addition, it takes time to replace turnouts. For example, Amtrak has committed to upgrade most turn- outs on the Northeast Corridor to a tangential geometry design. While this will increase speed as well as greatly improve ride quality, safety, and maintainability, Amtrak estimates that 25 years will be required to achieve a complete replacement. For these reasons, interest has grown in finding a low-cost means of increasing permissible speeds through turnouts that are compatible with the conventional AREMA standard designs. This paper presents the results of an FRA-sponsored study, Investigation of Low-Cost Techniques for Increasing Speeds Through Special Trackwork. The objective of the study was to identify potential turnout modification techniques that may be used to retrofit or upgrade existing turnouts for the purpose of increasing operating speeds. The results of the study led to the development of the new design turnout that will be presented here. PROJECT CONSTRAINTS As noted, turnouts are seldom completely replaced. In addition, mod- ifications that would alter the overall layout (geometry) of the turnout are generally costly and often impractical due to external physical conditions. Consequently, a constraint was established early that any feasible turnout modification would not require any change in the overall geometry of the turnout. Graphically this is demonstrated in Figure 1, where the lines A-A and B-B are used to show the bound- aries of the area that can be modified. Given the boundary lines estab- lished in Figure 1, only those modifications that do not change the relative placement of, and the angle between, the straight and diverg- ing sections of track (to the right of line B-B) could be considered Increasing Speeds Through the Diverging Route of a Turnout Without Increasing Lead Length Clifford S. Bonaventura, Allan M. Zarembski, Joseph W. Palese, and Donald R. Holfeld ZETA-TECH Associates, Inc., 900 Kings Highway North, Suite 208, Cherry Hill, NJ 08034.