The Dangers of Using Railroad Ties in Landscaping

ground cover plants spilling over retaining wall built of old railroad ties

James Lavin, Flickr, CC by 2.0

Using old railroad ties for landscaping is something homeowners have done almost as long as there have been railroads. In some places, railroad tracks no longer in use are becoming "rail trails" and the old wood and metal are removed. The heavy, durable wood seems like a no-brainer for those who want to use salvaged materials for greener home improvement. For decades, railroad ties have commonly been used to edge garden beds, or as part of retaining walls. But, as with many outmoded practices we learned from our grandparents or parents (like spraying dandelions with herbicide), we now understand that railroad ties are an environmental hazard.

The Issue With Railroad Ties

The main issue with railroad ties is the presence of creosote, a substance used as a preservative that is banned for residential uses due to its dangerous toxicity. Creosote is an oily by-product of the distillation of coal tar. Creosote treatment of railroad ties allows long term preservation of the wood which must obviously stand up to heavy pressure and harsh weather conditions.

You may also be familiar with creosote as a substance created by woodsmoke that can build up inside your wood stove chimney, as many wood stoves have gauges that indicate when creosote buildup may be happening. Creosote buildup in chimneys is dangerous because it can be flammable, potentially leading to a house fire. Creosote-treated wood used in gardens is harmful for a number of reasons, including direct exposure to the skin.

Dangers from Exposure to Creosote

Exposure to creosote can be dangerous for a number of reasons:

  • Risk of cancer
  • Chemical burns to skin
  • Eye irritation
  • Respiratory problems
  • Kidney or liver problems due to toxicity
  • Convulsions
  • Mental confusion
  • Death

Those are some very alarming potential hazards, so it should go without saying that using railroad ties is not recommended. Creosote exposure is not merely from direct contact with skin. Creosote can dissolve in water and take many years to break down, contaminating ground water in the meantime. This can affect humans, pets, wildlife and beneficial insects. Creosote in soil can also persist for decades.

Other Toxic Chemicals in Railroad Ties

Railroad ties may also be treated for chromated copper arsenate (CCA), a compound intended to prevent microbial or insect damage in wood. This compound typically contains chromium, copper and arsenic. CCA was commonly used for many years as a wood preservative before manufacturers of timber products switched over to creosote. Despite concern over environmental hazards, CCA is still in fairly wide use. Expose can cause arsenic poisoning, and the ashes resulting from burning wood treated with CCA has been shown to cause poisoning in livestock.

Disposing of Used Railroad Ties

Railroad ties should never be burned. This is true for all treated wood products, which may release toxic gases through smoke and cause illness or other hazards. The ash resulting from burned wood containing creosote has been shown to be toxic, also. Similarly, sawdust from cutting treated wood (such as railroad ties) should not be inhaled as it can cause respiratory problems (always use a mask or respirator when cutting wood of unknown origin).

Railroad ties can usually be disposed of in the same way as other solid waste, but you should be sure to check with your local county and municipal laws governing hazardous substances, as some places may not allow disposal of materials that may contain creosote or other toxic chemicals.

Raised garden bed made with cinderblocks
oc gardener, Flickr, CC by 2.0

Alternatives to Using Railroad Ties

Raised beds are great ways to add flower or vegetable beds to your garden. But it's important to use building materials that won't leach toxic materials into soil or the water table. A much safer option than railroad ties is old barn beams, if you can acquire them, but occasionally barn beams may be contaminated with substance such as motor oil or machine oil. Many communities now have groups interested in recycling or reusing salvaged architectural or building materials, so you may be able to locate wood or other materials to help you build your raised beds or create barriers for your plantings.