Boston — Let's say you're an East Coast distributor of products that have to be shipped all the way from California. With the economy picking up, you need new supplies to meet a sudden increase in demand.
But the soonest a shipment can arrive by rail is six days. While you wait, some of the trains that bring your shipment east may be chugging along at less than 40 miles an hour.
That speed could be nearly tripled, some who serve the railroad industry claim, if the tracks on which those trains roll were fastened to prestressed concrete crossties instead of wooden ones. The United States is one of the last major developed countries that hasn't made the switch. The average speed on rail lines in this country has been dropping over the last 30 years - to about 40 m.p.h. today.
Meanwhile, a French passenger train streaked to a world record 237 m.p.h. two years ago, and the Japanese bullet trains cruise to and from Tokyo at speeds in the area of 180 m.p.h. Both ride on rails laid atop concrete ties.
Adopt concrete ties, their producers say, and the average speed of trains on important US routes could climb to more than 100 m.p.h. - possibly making the difference between profit and loss for some companies.
Their advantages are many, according to spokesmen for the concrete industry. They offer a firmer ride than do wooden ties, resulting in a measurable improvement in fuel economy, less wear and tear on both train wheels and rails - especially on curves - less maintenance, and fewer derailments since the gauge of the track remains nearly constant. They also are more durable than wood, since they do not rot, warp, or burn.
But concrete ties have been slow to catch on with rail lines in this country. According to the Association of American Railroads (AAR), less than one-half of 1 percent of the 26 million ties laid in 1980 (the most recent year for which statistics are available) were ''other than wood.''
''We're a little ahead of our time,'' concedes William Read, chief of the railroad products group for Lone Star Industries, one of the major US producers of concrete ties. But if there is to be a railroad renaissance in this country, Mr. Read says, the use of these devices ''is certainly part of the picture.''
Concrete-tie makers have some notable successes to point to. The devices are used by metropolitan rapid transit systems in Boston, Atlanta, Chicago, San Francisco, and Toronto. Amtrak is installing 1.1 million of them as part of its Northeast Corridor improvement project between Boston and Washington. The Florida East Coast Railway is using them so extensively that it has its own manufacturing plant. Seven other US railroads are experimenting with them, as are the Canadian National, Canadian Pacific, and National Railway of Mexico.
One new customer, however, won't be Conrail, the 15,000-mile, federally owned rail freight system. Conrail uses few, if any, concrete ties, its spokesman says , because they cost more than the wooden ones. The line has budgeted $18.50 each for tie replacement this year, whereas the cost of one installed concrete tie can be as high as $60.
Other than higher cost, the concrete ties have some other shortcomings, according to critics. For one thing, the new ties haven't been proved under the variety of conditions endured by wooden ties. Also, their very rigidity means the concrete ties can't be interspersed in ones and twos with the more resilient wooden ties. Instead, they have to be installed along whole sections of track.
D.B. Mabry, executive secretary of the Railway Tie Association, a St. Louis-based trade group representing the major producers, says wooden ties have changed with the times, too. Pressure treatment with wood preservatives has lengthened their useful life to as many as 35 years. And speeds of 100 m.p.h. are just as attainable over wooden ties as they are on concrete, he adds.
In fact, the argument that speed records are set in other countries over concrete ties is misleading, AAR spokesmen say. The highest speeds are achieved not by freight but by passenger trains. Although the latter do not impose as much weight on the rails, their extreme speed still takes its toll. Originally, the Japanese wanted to use the bullet-train tracks for freight service at night. But they found the rails needed so much maintenance after their daily pounding that the idea was impractical.
''I don't think 100 miles per hour is necessary for freight,'' says Albert Reinschmidt, manager of track research for the AAR. ''Studies have shown that reliability is more important than speed - primarily from the standpoint of keeping inventories down.''