Click for next page ( 7

The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement

Below are the first 10 and last 10 pages of uncorrected machine-read text (when available) of this chapter, followed by the top 30 algorithmically extracted key phrases from the chapter as a whole.
Intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text on the opening pages of each chapter. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

Do not use for reproduction, copying, pasting, or reading; exclusively for search engines.

OCR for page 6
6 Truck Drayage Productivity Guide Table 21. Entry/exit transaction types. Entry Transaction Types Bare Empty on Load on Bobtail Chassis Chassis Chassis Bobtail in Chassis in Empty in Export in Bobtail Bobtail Out Bobtail Out Bobtail Out Bobtail Out Bare Bobtail in Chassis in Empty in Export in Chassis Chassis Out Chassis Out Chassis Out Chassis Out Exit Empty on Bobtail in Chassis in Empty in Export in Chassis Empty Out Empty Out Empty Out Empty Out Load on Bobtail in Chassis in Empty in Export in Chassis Import Out Import Out Import Out Import Out In both inbound and outbound moves, inspection of the chassis may require more time than inspection of the container itself. This situation would change if, and when, chassis are no longer interchanged with the terminal operator or kept on the terminal. There are many possible exceptions and variations in this process, such as: Dual transactions (e.g., empty return/import load, export load/import load, export load/empty pickup); Trouble-window transactions (e.g., documentation problems, turnaways, or the need to pick up a different container); Equipment issues (outbound chassis roadability, inbound damage dispute, delays for repairs); Off-terminal storage or repair trips (significant where refrigerated containers must be "pre- tripped" for perishable exports); and Dray-in imports (imports coming into the terminal that were discharged at another port) and dray-off exports (exports being re-delivered to shippers instead of being loaded onto a vessel). All port drayage processes at terminals have the same basic objectives and the same basic steps. The following sections describe generic drayage processes for import, export, and empty moves. The complete cycle may involve more than one driver on separate days. Marine Container Terminals Marine container terminals all served the same basic functions but differ in ways that affect drayage operations. "Wheeled" terminals park containers on chassis. From a drayage driver's point of view, a wheeled terminal is a self-service parking lot in which he leaves and picks up containers on chassis without interacting with terminal personnel inside the gates. For this reason, wheeled terminals are usu- ally the easiest and most economical for drayage firms to serve. Wheeled terminals require an on-terminal chassis supply, and are rare outside the United States. "Stacked" terminals store containers and chassis separately. Container yard lift machines, such as straddle carriers, rubber-tired gantries (RTGs), or sideloaders are used to stack containers and transfer them between stacks and chassis. To drop off a container, a driver waits at the storage area for the container to be lifted from the chassis, and then parks the chassis in a separate area (unless he reuses the chassis for an outbound move). To pick up a container, a driver must locate a suit- able bare chassis (if he does not have one from a previous move) and take it to the storage area to receive the container. Serving stacked terminals typically takes longer and has more opportunity for exceptions and delays than serving a wheeled terminal.

OCR for page 6
The Port Drayage Process 7 TOP-PICK EMPTY HANDLER REACH STACKER SIDE LOADER STRADDLE CARRIER RUBBER-TIRED GANTRY (RTG) RAIL-MOUNTED GANTRY (RMG) Figure 21. Container yard handling equipment types. At "transfer zone" terminals, a driver dropping off a container waits in a designated area to be served by a mobile lift machine. A driver picking up a container waits in the transfer zone with a bare chassis, and the mobile lift equipment brings the container. In both cases, the driver must move the bare chassis to and from a separate area. Almost all major U.S. container terminals are actually hybrids, with some containers wheeled on chassis, empties handled by mobile lift equipment, and loaded containers handled by RTGs or straddle carriers. Typical handling equipment types are shown in Figure 21. Rail-mounted gantries (RMGs) are uncommon in the United States. Figure 22 displays the progression of terminal handling methods from lowest to highest den- sity. Virtually all U.S. marine container terminals use a mix of the handling methods shown in Figure 21, and vary that mix to provide sufficient capacity at minimum cost. Terminal operators gravitate to low-density, low-cost operating methods whenever possible. DENSITY TYPE COMMENT Ro/Ro or Ship's gear Very small, barge, specialized VERY LOW DENSITY Wheeled Combination Small, mixed, legacy Dedicated Wheeled Older terminals when new Wheeled/Top-pick Transition terminals LOW DENSITY Top-pick/Wheeled Transition terminals Straddle/Top-pick/Wheeled Hybrid terminal MID DENSITY RTG/Top-pick/Wheeled Dominant hybrid type Straddle Carrier NIT Virginia HIGH DENSITY RTG No US Example VERY HIGH DENSITY Pure RMG APM Portsmouth Figure 22. Progression of terminal handling methods.