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Shared-Track: A Handbook of Examples and Applications 59 b. The lower acceleration and braking rates of compliant DMUs are not conducive to the frequent stops required for an effective downtown service design. This equipment also is unsuited to an operation that may require traffic light stops. c. The residents of downtown are concerned about the noise and vibration generated by a compliant commuter rail car operating in the street. A lighter rail car with a smaller diesel engine would generate substantially less noise (comparable to common motor vehicle or bus). d. The option to construct a new grade-separated railroad to reach the downtown was not considered due to its high expense and inability to serve multiple stops within the city. 4. Two other alternatives are to consider terminating a commuter rail service at a main station and serving the dispersed demands of downtown via a transfer; or to provide two-seat-rides. Two typical scenarios for the latter are: a. Hourly commuter rail service with bus connection. This is an economical option with much potential, requiring one push-pull trainset and a fleet of buses; b. Quarter-hourly commuter rail service with light rail connection. An option entailing high capital and operating costs compared to a shared-track option. Separate vehicle fleets and facilities are required for the street running and railroad portions of the routes respectively. The transfer penalty of five minutes represents an increase of 20% to 45% in journey time. A ridership decrease may result. A sample analysis worksheet is shown in Table 8. Overview of Shared-Track Options--Operating Plan Prepare a summary review of typical and most likely alternative operating regimes that would share track or ROW with a freight operator. The four listed cover the broadest range of choices. Other permutations are possible, perhaps modifying or combining aspects of the four shown below. For each operating regime, a different service plan, infrastructure, physical plant, and train control system is required. This approach can be tailored to site-specific circumstances. Table 9 summarizes the important systemic differences between the operating plans and the associated infrastructure, physical plant and systems for the four options. Structures Considerations If there are major structures on the route, then these structures must be inspected and rated for passenger service. In some scenarios, the structures must be expanded, replaced, or new structures erected. Structures affected could be none, some, or all of the following: Overbridges and overpasses; Elevated sections or viaducts; Grade separations; Shared ROW and retaining walls with highways; and Bridges over rivers or bodies of water. Typical structural changes should be identified and recorded on a worksheet similar to Table 10. Table 8. Worksheet 2--Ridership impacts of forced transfer. Suburban Time to Increase Inbound Boardings Outbound Total Originating Downtown in Travel Disembarkations Ridership Station (Minutes) Time Direct Forced Direct Forced Losses Service Transfer Service Transfer Total