Warning tracks: material selection, construction and maintenance
By Paul Schinner
We’ve all heard the story: a warning track on a baseball field is designed to give the players two to three steps “notice” at full stride, before crashing into the wall. Right? Well, partially right anyway, in my opinion.
There are other good reasons that warning tracks exits. Aesthetically, a red warning track can be a stunning contrast to a lush field of green grass. Throw in a nice mowing pattern and a baseball field is as much a work of art as a playing surface and the track is an important part of the canvas.
The track also serves as a roadway for tractors, utility vehicles, mowers and other equipment to keep them off the grass. I have seen and been part of 5K and 10k races that finish on a MLB warning track. I can imagine the horrified look on a groundskeeper’s face if 3,000 runners were hitting the finish line on their grass infield. Occasionally, cars, floats, fire trucks or horses use the track to deliver team mascots and celebrities to the field for events and ceremonies. So, while player safety may have been the invention of the warning track, there are many other reasons to understand and care for them.
Professional help recommended
Whether starting from scratch on a new field construction or renovating an existing field I recommend hiring a design professional. There are numerous highly qualified landscape architect/civil engineers that specialize in sports field specifications and design. A good designer will take into account the local weather conditions, field use, maintenance capabilities, budget and the overall performance expectation of the owner.
A good warning track design will drain water. This can be done several ways. A material that is designed to drain through may be built over a free draining stone base with drainage pipes underneath to carry water away, while a tighter, more compactable material may need to slope one direction or another and sheet the water away to a trench drain. If budget is a limiting factor, as in a youth, park or rec field situation, find a local contractor that specializes in this type of work and give them a call. There are many professional contractors and groundskeepers in the industry that volunteer their time to help local groups keep up their fields. See the Sports Turf Managers Association (www.stma.org) or American Sports Builders Association (www.sportsbuilders.org) websites for more information.
Build a good base. Whether your track will be flat or sloped, it is vital to have a good base to build on. Subgrades are typically 4 to 10 inches below the finished grade. Make sure your subgrade is compacted and graded to match the finished grade of the surface. Over the years I have found that a good proof roll will tell me more than some expensive compaction testing; all it requires is a Bobcat with a loaded bucket driving back and forth. As you find any soft areas, go around and excavate the area until you get to solid ground; then fill in the hole with good compactable soil or stone in 3 to 4 inch lifts and compact in between each lift.
Once you have filled in any soft spots, repeat the proof roll again to be sure you have fixed the problem. Some subgrades are deeper and have a layer of crushed stone under the warning track material, but the same principle applies. You also want to make sure that the subgrade matches the finished grade, or in the case of a track with a stone base, that the top of the stone matches the surface grades.
If your grades do not match, you will end up with areas that have more or less of your warning track material and this will cause problems. It can also lead to having to use more material, which will cost you money. Most of the warning track products available today are not inexpensive, so you will not want to waste it.
Maintenance of a warning track can vary based on material, use, budget and staff availability. Most high profile venues will treat the track similar to the infield clay by dragging and rolling regularly. You have to use the same care not to drag the material into the grass as you would on your infield. Regularly clean up any trash, grass clippings, peanut shells or sunflower seed that tend to end up on the track. This trash can end up turning to a fine powder and can affect the drainage through the track.
Try to vary your path when driving rubber tired equipment on the track to try to minimize compaction. When compaction and slower drainage rates become an issue after a few years, scrape off the top ½ to ¾ inch and remove, then scarify the next 1 inch and add new material to the top. This can extend the life of the track and help keep it functioning as designed.
Paul Schinner, CFB, is vice president of operations, The Motz Group, LLC, and a Certified Field Builder member of the American Sports Builders Association. He can be reached at