Have you ever heard that scheduling is to dispatching as budgeting is to finance? One cannot dispatch oneself out of an overbooked situation any more than one can achieve financial success with creative bill paying.

I am often told that dispatchers are more efficient if they are running late. But how late must a dispatcher run to feel this pressure? Is 10 minutes enough or is 30 to 60 minutes needed? What does this do to customer service and satisfaction?

So how does a dispatcher avoid overbooking and provide good service? Dynamic Scheduling is a dispatching tool that keeps the dispatch staff informed of truck and plant commitments and displays any overbooking or underbooking situations. Since it is part of a package which includes order entry, ticketing, and truck tracking, as well as other programs, separating out the savings by program is difficult. Scheduling has the greatest impact on savings but tends to be less glamorous than truck tracking, so it is often glanced over.

A typical concrete producer in the U.S. achieves 64% truck utilization. This means that trucks average 6.4 hours of actual work in a 10-hour day. Work is defined as loading, slumping, traveling, unloading, chute washing, and returning.

Excluded from productive or work time is getting ready (startup), waiting in the yard for a load, waiting on the jobsite to unload, and waiting at the end of the day to start wash-up. Dynamic Scheduling by Command Alkon is designed to reduce delivery costs in these four areas. After all, 3.6 hours is a lot of time to be nonproductive. Even a 10% reduction (0.36 hours or 22 minutes) is significant. At $60 per hour to operate a truck, 0.36 hours equals $21.60 per truck per day.

Reducing idle time

A good concrete dispatching schedule needs to keep everyone informed of the latest plan. The dynamic part is required as the day's plan keeps changing and the schedule must be kept up to date to be relevant. Your dispatcher's data display must provide a multitude of information to promote decision-making that will make these reductions in nonproductive time possible.

The display needs to show not only truck commitments by plant but also whether these plants can batch the concrete at the rate required. A list of all orders in the schedule is needed, along with a graphic display of each order's truck and load requirements so orders can be juggled if there are conflicts.

A driver report time schedule is needed if start-up time is to be reduced. An idea of when to wash out trucks is needed to reduce dead time waiting for wash-out and shut-down at day's end. Any overbooking must reflect how far overbooked a plant is and when trucks will be free so new orders can be taken. If there is too much demand in the morning, a pre-loading display is needed to indicate how much time is being wasted.

Dynamic Scheduling uses a familiar graphic presentation with truck requirements on the Y axis and the time of day on the X axis. Each plant can be shown in a separate display or overlaid on the fleet display. See Figure 1.

Dynamic Scheduling in conjunction with a driver call-in report calculates the exact loading time for each truck from which driver report times can be determined. Loading conflicts are dealt with by pre-loading loads so two loads are not scheduled at the same time.

While pre-loading is often required, excessive pre-loading wastes time and money. In Figure 1, the burgundy area at the beginning of Plant 1 shows there is excessive pre-loading. The customer service representatives should begin negotiating with customers about start times for their orders to avoid preloading. Suggesting an earlier or later start time, often by only 15 minutes, is often adequate.

At the same time, loading the trucks early just to get them out of the yard is often counterproductive. Instead of wasting time in the yard, the fully loaded trucks are wasting time on the jobsite. At this point the producer no longer has options for using the trucks elsewhere or for last-minute orders. It is usually better to waste time in the yard and keep the options open.

Loading late is an even more critical adjustment because if a contractor waits for concrete, the producer can't catch up by sending trucks faster than ordered.

Truck scheduling

Dynamic Scheduling constantly updates the schedule with orders as they are entered, deleted, or changed. Each ticket generation initiates another schedule update.

Sometimes overbooking is unavoidable. If a producer is overbooked, when can new orders be taken? Figure 3 illustrates the problem.

As the demand for trucks tapers off at the end of the day, the drivers should wash their trucks and clock out. The graph shows when this is likely to occur so the dispatcher can anticipate the time and plan ahead. With the help of such tools, careful planning, and customer negotiation, you can achieve a more flat graph indicating that there are no “gaps” in the schedule while the trucks are doing nothing but waiting.

As loads are generated, each subsequent load for an order is dynamically rescheduled to maintain the ordered rate. Large deviations from the ordered rate are displayed on truck tracking so the dispatcher can take remedial action. Dynamic Scheduling does not “learn” the unload rate and automatically apply it; it maintains the ordered rate. Learning the rate and adjusting is a job for Dispatch Optimization with COMMANDoptimize.

James Wagner is vice president at Command Alkon. For more information, visitwww.commandalkon.comand booth #S-9923 at CONEXPO-CON/AGG.