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Terminal Versus Overall Turn Times The key measure of drayage performance within the terminal is turn time, the time required to complete an activity cycle. In the large picture, turn time refers to the entire round-trip move- ment between port and customer or rail terminal. Those turn times are, however, customer spe- cific and location specific, and influenced by distance, highway conditions, business practices, drayage strategies, etc. There are two different turn times associated with marine terminal visits, as follows: ⢠The terminal turn time recorded by the marine terminal is gate to gate, triggered by arrival of the drayage driver at the entrance gate and ended when he leaves the exit gate. These recorded turn times range from a minimum of about 10 minutes for a completed simple transaction to as much as 8 hours. Marine terminals have no data on drayage activity out- side those gates. ⢠The overall turn time experienced by drayage drivers, however, includes queuing time before they reach the terminal gate itself. The additional time spent waiting outside the entrance gate has been reported in various surveys to be as long as 2 hours. The study team observed waiting times ranging from effectively zero when there was no queue, to 4 hours or more when termi- nal operations were severely disrupted. Turn Time Distributions Gate-to-gate terminal turn times typically show, as expected, a skewed distribution (Fig- ure 5â1). The first terminal shows a few unusually quick transactions of less than 30 minutes, a large number of ânormalâ transactions of 30â60 minutes, and a few much longer transac- tions that reflect exceptions. The second, more heavily used terminal shows somewhat longer turn times but the distribution has the same overall shapeâskewed toward the longer turn times by exceptions. The ânormalâ time varies with the complexity of the transaction and the type of terminal. Figure 5â2 compares a distribution of port-wide trucker turn times (includes queuing) with ter- minal turn times (does not include queuing) from one of the terminals in the same port. Although the comparison is not precise, the available data suggest that the truckerâs turn times typically include 20â30 minutes of queuing time, shifting the distribution to the right. The critical factor is the common shape of the distributions in Figure 5â1 and Figure 5â2. In each case there are roughly 5% of the trips in the extended right-hand âtailâ of the distribution that experience much longer turn times and account for a disproportionate share of drayage time, cost, and emissions. The system is effectively operating at âtwo sigma,â with about 95% 39 C H A P T E R 5 Truck Turn Times
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 5â3. Figure 5â3 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. 40 Truck Drayage Productivity Guide Figure 5â1. Gate-to-gate turn time distributions. Figure 5â2. Trucker and terminal turn time comparison. 0% 5% 10% 15% 20% 25% 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 Fr eq u en c y Import Loads Export Loads (a) Terminal 1. 0% 2% 4% 6% 8% 10% 12% 14% 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 Fr e qu en cy (b) Terminal 2. 0% 2% 4% 6% 8% 10% 12% 14% 16% 18% 20% 0-1 5 15 -30 30 -45 45 -60 60 -75 75 -90 90 -10 5 10 5-1 20 12 0-1 35 13 5-1 50 15 0-1 65 16 5-1 80 18 0-1 95 19 5-2 10 21 0-2 25 22 5-2 40 24 0-2 55 25 5-2 70 27 0-2 85 28 5-3 00 Example Terminal Turn Time Port-wide Trucker Turn Time
Figure 5â4, 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. Truck Turn Times 41 Figure 5â3. Drayage turn time segments. Figure 5â4. Terminal turn time variability by segment. 0 5 10 15 20 25 30 35 40 45 50 Jan Feb Mar Apr May Jun Jul Aug Sep A ve ra ge T ru ck T ur n Ti m e (m inu tes ) Entry Gate Process Yard Process Exit Gate Process Source: Port terminal data, outliers removed. -10.00 0.00 10.00 20.00 30.00 40.00 50.00 60.00 70.00 Jan Feb Mar Apr May Jun Jul Aug Sep A vg . P ro ce ss in g Ti m e +/ - O ne S td . D ev . (m inu tes ) Entry Gate Process Yard Process Exit Gate Process Source: Port terminal data, outliers removed.
Within the terminal, the major determinants of turn time are as follows: ⢠The nature of the transaction, ⢠On-terminal chassis supply, ⢠Congestion in container stacks or parking areas, and ⢠Exceptions and trouble tickets. Causes of Long Turn Times Congestion at marine terminal gate queues and container yards is primarily caused by peaking, and can be exacerbated by limitations on working hours, external factors such as the OffPeak Pro- gram, or shortcomings of legacy facilities. ⢠Longer turn times can be expected for more complex transactions. Truckers prefer âdoubleâ moves (e.g., returning an empty container and pulling an import load on the same trip) rather than making two trips for the same work. ⢠On-terminal chassis supply is a focal point for process improvements and long-term institu- tional change, and is discussed in more detail later in the guidebook. ⢠Congestion in container stacks or parking areas is a function of terminal CY capacity, lift capa- bility, configuration, and peaking. Peaking is endemic in containerized shipping, and it would be impractical to build terminal capacity for the peak volumes. The bigger issue is the division of lift capabilities and staffing when vessels are in port. ⢠Exceptions and trouble tickets add an average of about an hour to affected moves. At about 5% of the total, trouble ticket transactions add about 3 minutes to overall average turn times. On a given day, turn times for trucks can vary substantially, even when trucks enter the ter- minal under similar conditions. There are a number of factors that can extend the time required. The average (mean) daily turn time may provide very little information about what is possible for any individual truck that day. When a terminal is operating close to its capacity, the prob- ability of high turn times significantly increases. In examining the patterns of delay throughout the day, the researchers found that turn times tended to come down later in the afternoon as the number of arrivals dropped. Furthermore, the probability of a truck experiencing an extra long turn time was lowest toward the end of the day. It should also be noted that the capacity of a terminal is dependent not only on the physical attributes of the terminal such as the num- ber of lanes and cranes, but also the amount of labor that has been assigned to work a particu- lar shift. Terminals attempt to anticipate high-volume periods and assign labor accordingly. If the terminal misjudged the volume for a particular day, higher average turn times and greater variability can result. The impact of congestion can be seen in the relationship between volume and turn times in Fig- ure 5â5. Although the general relationship is clear, the specifics will vary by terminal. In the exam- ples, the first terminal is relatively unaffected by volumes of up to 1,100 per day while the second shows marked increases in turn times for volumes above that level. Suboptimization A substantial portion of the delays and bottlenecks in port drayage are traceable to suboptimiza- tion of the complex intermodal system. Drayage firms and marine terminals would both prefer an even, predictable, and uninterrupted workload over the day, week, month, and year. The context in which they operate, however, makes that unlikely to ever happen. A system optimized for the drayage customers (the importers and exporters) is unlikely to be optimal for the marine terminal customers (the ocean carriers). 42 Truck Drayage Productivity Guide
There is no one in charge of the entire process, so rational and well-informed actions by partic- ipants still do not optimize the whole. It is helpful to place drayage and terminal operations in context. Drayage of marine containers to and from port terminals is a complex process involving interactions between customers (importers, exporters, 3PLs), ocean carriers, terminal operators, and trucking firms. The funda- mental transaction is between the ocean carrier and the customer, with the customer paying for waterborne transportation of the goods inside the container. Marine terminal operations and drayage are intermediate steps, and both must cope with the movement preferences, policies, and capabilities of the ocean carriers and their customers. This intermediate position requires both drayage firms and marine terminals to cope continually with unevenness of demand, inconsistent priorities, mismatched information flows, and cost pressure. Truck Turn Times 43 Figure 5â5. Congestion impacts. Drayage Volume vs. Average Turn Time - Jan - March 2009 - 10 20 30 40 50 60 70 80 90 0 200 400 600 800 1000 1200 Number of Trucks Entering Av er ag e Tu rn T im e (m in) (a) Case 1. Import Deliveries vs. Non-Trouble Turn Time - 2008 30 40 50 60 70 80 90 100 500 700 900 1100 1300 1500 1700 1900 2100 Daily Import Volume Av g. T ur n Ti m e (m in) (b) Case 2.
The direct customers of the drayage firms are usually the importers and exporters. (Although so-called âstore doorâ drayage is theoretically controlled by the ocean carriers, in practice, the importers and exporters often chose the drayage driver.) The primary goal of importers and exporters is to obtain their import goods (or ship their export goods) at their preferred time at low- est possible cost. Customers see the cost, time, and uncertainty associated with drayage and seek to minimize all three, but are first and foremost concerned with the cost. The direct customers of the marine terminal operators are the ocean carriers. Although marine terminal operators do pay attention to the needs of importers, exporters, and drayage firms, the ocean carriers pay the bills. Many marine terminal operators, such as Eagle Marine Services and APM Terminals, are ocean carrier subsidiaries. The primary goal of the ocean car- riers is to turn the ship (unload import boxes and load export boxes) on schedule at lowest pos- sible cost. Carriers will pressure terminal operators (even their own subsidiaries) to handle the vessel on schedule at lowest possible cost, regardless of impacts on other terminal functionsâ notably drayage. As a result, drayage queues lengthen and turn times rise while a vessel is being worked. Although the ultimate customer pays the entire cost, that customer does not see all the compo- nent parts or the tradeoffs between them. An importer with a âstore doorâ rate will receive a sin- gle bill from the ocean carrier, with no breakdown between ocean, terminal, and drayage costs. An importer or exporter with a âlocalâ rate will pay for drayage separately, but will not see a break- down between terminal and ocean costs. Need for Buffers Vessels arriving at the terminal unload a large number of containers in a relatively short time. The vessel arrival therefore creates a backlog or stockpile of import containers on the ter- minal, which draymen will pick up and deliver over the next few days. Vessels departing the terminal likewise load a large number of outbound containers in a relatively short time, clear- ing the terminal of a backlog that draymen created by delivering export loads and empties over the previous week. The desire and ability of import customers to receive containers may bear little relation to the pattern of vessel arrival. One customer may want âhotâ boxes immediately, while another may want arrivals spaced out over several days. At most ports the typical pattern is for import pick-up demand to peak on the day of first availability (usually the vessel arrival day), and to taper off thereafter. Empty container returns will lag import pickups by a day or more. Export loads typically build up in the week prior to vessel arrival, often peaking the day before the out- bound cutoff. The flow of containers between vessel and landside customer is therefore anything but smooth. Rather than a steady conveyor-like stream, the flow is a series of surges. Any system that must accommodate uncoordinated flows and surges requires buffersâ intermediate stopping or storage points that allow parts of the system to operate at different rates or on different schedules. As a buffer, however, the gate queue is costly, inefficient, and envi- ronmentally unsound. Each container in a terminal gate queue is being attended by a driver, chas- sis, tractor, and diesel engine burning fuel and emitting pollutants. Best practices should conserve some or all of those resources by minimizing the time in the queue. The potential for uneven arrivals, the fixed throughput capacity of the gates and the terminal, and the relative difficulty of adapting the number of open gates together imply the need for a buffer in the system. The marine terminal gate acts as a metering device, with the queue outside serving 44 Truck Drayage Productivity Guide
as a buffer. Appointment systems reinforce this metering function. Terminals make only as many appointment slots available as the CY can handle. The gate queue is currently functioning as the buffer. Some sources refer to the queue as the âholding pen,â which is an accurate, if somewhat unflattering, description. Turn Time Solutions Terminal Capacity and Performance With such a large part of drayage inefficiency and delay traceable to congestion, terminal capac- ity and performance is a logical place to look for improvement. Annual terminal throughput capa- bility is less important in this connection than ability to handle surges. In particular, the ability of a terminal to sustain efficient high-volume trucking operations at the same time a vessel is being served is crucial, and often lacking. It is common to reduce the scope of drayage transactions while a vessel is being worked, either by restricting operations, such as empty returns, or by closing off busy areas of the terminal. Drayage drivers may find gates understaffed, lift machines busy, and clerks preoccupied with other tasks on vessel days. One promising approach is to design the terminal so truck and vessel operations do not overlap or share equipment. The APM Portsmouth terminal and the proposed Ports America terminal for Oakland are examples of designs with container stacks perpendicular to the vessel. These stacks are served by one set of gantries to load and unload the vessel from the berth end, and by a second set of gantries to load and unload drayage trucks on the CY end. Such large-scale investment and reconfiguration is beyond the short-term need and capability of most port terminals. More modest means of improvement would include enough efficient lift equipment and staffing to handle both vessels and trucks in existing configurations. If the gate throughput capacity is the same as the terminal CY throughput capacity, there may be no point in speeding up the gates, since it would merely result in CY delays instead. From the terminalâs perspective, there is no need to improve gate throughput since, as long as there is one limiting factor, overall efficiency is compromised. However, from the drayage driverâs perspec- tive, they would still like to see congestion-free gates because then they at least have a chance of getting through within an acceptable time window provided they are not particularly unlucky within the terminal. If the gate capacity is less than the terminal capacity, then the gates are a bottleneck and a case can be made for speeding them up or opening more when a queue develops. Speeding up the gates through institutional or technological means is probably a long-term solution and would apply to all days and all gates. Likewise, building more gates would be a long-term endeavor. Port Community Meetings Regular meetings between port or terminal officials and major dray companies are an effective strategy for identifying bottlenecks and inefficiencies. The introduction of Web-accessible termi- nal information also has been an effective strategy for providing dray companies and drivers with greater information as to port processes. The working relationship between all of the parties involved improves with regular contact and communication. Although terminal operators do not earn more revenue for faster drayage turns, they do bear the additional costs for clerical handling of trouble tickets and additional CY staffing or equipment to handle congestion. Truck Turn Times 45
For over 20 years, the Port Authority of New York and New Jersey (PANYNJ) has been conven- ing semi-monthly port user group meetings. These meetings include ocean carriers, marine termi- nal operators, International Longshoremenâs Association (ILA) representatives, drayage firms, customers, and third parties. The meetings provide a venue for announcing and discussing planned developments and changes, solving problems, and forging an ongoing working relationship between the parties. In the observation of the research team, these meetings have resulted in a far better mutual understanding of concerns and goals. The longevity and regularity of these meetings also has given the Port Authority and its staff much deeper insight into the operations and con- cerns of the port community than would be gained from occasional issue-based meetings. The Port of Houston Authority also has convened periodic meetings with drayage firms and both parties report these meetings to be valuable and productive. Such meetings do not solve every problem. The differing interests and goals of the parties make some degree of conflict all but inevitable. The meetings do facilitate solutions when solutions are possible, and encourage cooperation and communication on other less controversial matters. Segment by Segment Improvements Overall turn times are made up of multiple time segments: gate queuing, gate processing, chas- sis supply, CY operations, etc. Each of these time segments is treated in the guidebook chapters that follow. A comprehensive approach to drayage turn time reduction would entail identifying and prioritizing the drayage activity segments with the greatest delays and addressing them individu- ally. Care must be taken, however, to acknowledge and manage tradeoffs. 46 Truck Drayage Productivity Guide