12.3 Moving Freight by Rail 1. Intermodal operation between rail and truck 2. Compute rail resistance and locomotive power Chapter objectives covered in CE361: By the end of this chapter the student will be able to:

Chapter Intermodal Rail/Truck Truck Trailers on Flat Car (TOFC)  RRs carry more than 40% of the nation’s intercity freight  RRs carry about 70% of the motor vehicles made by domestic manufacturers.  RRs carry about 64% of the nation’s coal  RRs carry about 40% of the nation’s grain om/watch?v=FoR1Lti1 ujE

Chapter 12 3 The Increasing Role of Containers  Efficiency of transporting commodities from the manufacturer to retailers helps reduce costs, thus prices.  Standardized container size helped their transfer from one mode to another quicker and easier.  The container movement began with railcars carrying truck trailers on flat cars, called TOFC.  Benefits: No driver needed for a long haul and a large number of trailers can be transported by rail at one time  Disadvantage: The air-space below the trailer is wasted, It increases air-drag, They are non-stackable. Truck Trailers on Flat Car (TOFC)

Chapter 12 4 Then changed to COFC Containers on Flat Car (COFC) Intermodal Rail/Truck Yard, SLC  Benefits:  Containers on Flat Car (COFC) do not have the aerodynamic drag disadvantages that TOFC has.  Stackable  Energy savings over TOFC  Disadvantage: Required a full truck chassis at the intermodal yard to go the remainder of the trip by truck.

Intermodal yards Chapter 12 5 TOFC = Trailers on Flat cars COFC = Containers on Flat cars Evolution to more cost effective operations

Chapter 12 6 Relative Cargo Capacity of Three Freight Modes Each truck needs a driver. Labor cost is high. Hence, commodities carried by trucks have higher dollars per ton-mile costs.

Standard track gauge in the US Chapter 12 7 Standard gauge in the US = 4 feet 8.5 inches

Chapter Rail Resistance and Locomotive Power Rail Resistance: For locomotives to pull a train, they must overcome resistance from four main causes: Rail Resistance: For locomotives to pull a train, they must overcome resistance from four main causes: Resistance R tt1, from the weight of the trailing train Resistance R tt2, from the aerodynamic drag Resistance R grade, from the ruling grade (steepest grade along the train’s route) Resistance R curve, from the most severe horizontal curve w = weight of loaded car per axle (tons) V = velocity (mph) K = aerodynamic coefficient n = number of axles per car G = ruling grade (percent) ∆ = degree of curvature (degrees) tt = Trailing ton, lbs/ton TE drawbar = R total *C*w*n TE  Tractive effort

Examples Chapter 12 9

Total tractive effort required to pull the trailing cars (p.12.17) Chapter Resistance: Propulsion: One HP = 550 ft-lbs/sec

Number of locomotives needed Chapter 12 11

What if the train runs on a grade? Chapter 12 12

Chapter What if the train runs on a grade & on a curve?