Key Takeaways

  • Crushed stone, sand and gravel are called “construction aggregates” and they are used in virtually every construction project, from roads to runways to buildings and sewer systems.
  • In 2016, U.S. Class I railroads originated 1.2 million carloads of stone, sand and gravel (4.3% of total carloads) carrying 128.9 million tons (8.6% of total tons) and earning gross revenue of 2.3 billion (3.5% of total revenue).

Construction aggregates — like crushed stone, sand and gravel — are found in nearly every state in the nation, making long distance shipments of these materials unnecessary.

As a result, freight trains, which typically specialize in long-haul movement of freight, may seem like an unlikely transportation partner.

However, over the past decade, efficiency enhancements and investments have allowed railroads to become serious players in the movement of rock. And because one railcar can carry as much aggregate as four truck-trailers, freight rail is an environmentally friendly way to move aggregates.

Aggregates are used in virtually every construction project, from roads to runways to buildings and sewer systems. Analysts estimate that that approximately 80% of U.S. crushed stone is used as a construction material, mainly for road construction, while 43% of U.S. sand and gravel is used for concrete aggregates.

“Raw materials — crushed stone, limestone, sand, gravel and gypsum—are transported (by rail) from quarries or suppliers to cement and ready-mix concrete plants where cement and clay products materials (such as brick and tile, concrete, wallboard and plaster) are produced,” researchers at Towson University’s Regional Economics Studies Institute noted.

“These materials are then transported to construction distribution centers and construction sites. Each of these raw materials serve an essential function in the construction process. Construction sand, aggregates and cement are used in building foundations. Gypsum is used for wallboard production, plaster, and sealants. Clay-base ceramic tile is used in floors and walls,” they said.

Texas is the largest producer and consumer of aggregates among the 50 states. In fact, Texas’ growing population — particularly around Houston and Dallas, Ft. Worth — has driven the most demand for aggregates shipped by freight rail.