Click for next page ( 41


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 40
40 Truck Drayage Productivity Guide 25% 14% 12% 20% 10% Import Loads Export Loads 15% F re q u e n c y F re q u e n c y 8% 6% 10% 4% 5% 2% 0% 0% 0-10 10-20 20-30 30-40 40-50 50-60 60-70 70-80 80-90 90-100 100-110 110-120 120-130 130+ 0-10 10-20 20-30 30-40 40-50 50-60 60-70 70-80 80-90 90-100 100-110 110-120 120-130 130+ Minutes Minutes (a) Terminal 1. (b) Terminal 2. Figure 51. Gate-to-gate turn time distributions. of the transactions (about two standard deviations from the mean) in the expected range and 5% outliers. Turn Time Components Most terminal turn time data are not segmented, so only the total turn time is available for each transaction. One of the case study terminals, however, made segmented data available for import deliveries, as shown in Figure 53. Figure 53 shows clearly that most of the time at the terminal (once past the queue) is spent in the calendar year (CY). For modern terminals with a high degree of gate automation, the actual time spent at the gates is usually only a few minutes. 20% 18% Example Terminal Turn Time 16% Port-wide Trucker Turn Time 14% 12% 10% 8% 6% 4% 2% 0% 0 10 5 15 5 0 5 0 15 0 22 5 27 0 12 0 13 5 19 5 16 5 24 0 28 5 0 18 0 25 5 21 0 0 -3 -7 -9 -4 -6 19 18 15 22 25 27 12 13 16 21 24 28 30 -1 0- 75 15 30 45 60 5- 0- 0- 5- 5- 0- 0- 0- 5- 5- 0- 5- 5- 90 Figure 52. Trucker and terminal turn time comparison.

OCR for page 40
Truck Turn Times 41 50 Entry Gate Process Yard Process Exit Gate Process 45 40 Average Truck Turn Time (minutes) 35 30 25 20 15 10 5 0 Jan Feb Mar Apr May Jun Jul Aug Sep Source: Port terminal data, outliers removed. Figure 53. Drayage turn time segments. Figure 54, from the same source, shows that the variability of the CY process is also far greater than the variability of the gate processes. Accordingly, CY processes are a major focus for identify- ing potential bottlenecks. The relatively small amount of time spent at the gate itself might seem to diminish the impor- tance of gate processing in attempts to reduce turn time. Gate processing times, however, determine outside queue times when trucks arrive faster than they can be served. Each unnecessary minute at the gate is multiplied by the number of trucks in line. 70.00 Entry Gate Process Yard Process Exit Gate Process Avg. Processing Time +/- One Std. Dev. (minutes) 60.00 50.00 40.00 30.00 20.00 10.00 0.00 Jan Feb Mar Apr May Jun Jul Aug Sep -10.00 Source: Port terminal data, outliers removed. Figure 54. Terminal turn time variability by segment.