What damage can be caused by traffic on frozen greens?

Our regular greens have been closed since Thursday and we have been forced to utilize temporary greens for play.  The sub-zero nighttime temperatures on several consecutive nights that we've been experiencing have resulted in frozen greens.  The problem with playing on the greens right now is that they are not frozen enough.  If they were frozen at a depth of 4" or more and frost-free at the surface, they'd be open for play.  Right now the deepest they've been frozen is no more than 2.5" below the surface.  Even worse, when they are thawing during the daytime, there are large sections of them that are only thawing to a depth of about 1/2".  This is when the greens are prone to severe damage.  I completely understand the frustration that many have with the regular greens be closed on a beautiful sunny day and I am also well aware that there is a feeling amongst some that we are being too overprotective of the putting surfaces, but please take the time to read this excerpt from the USGA Green Section that describes just how damaging it would be to open the greens under these conditions:

"Another dangerous situation exists when the soil is completely frozen to the surface but the grass blades have thawed. Provided there is no frost or ice on the grass under this condition, then limited foot traffic creates little damage, if any.

At these times, heavy traffic or golf carts should be restricted from greens, tees and even fairways. This is the most favorable winter conditions, because when the soil is frozen it does not allow as much penetration of compaction and spikes, thus preventing damage to the grass roots. Since the blades are not frozen, they retain the resiliency needed to withstand light foot traffic.

Traffic damage on frozen turf areas usually occurs during periods of freezing or thawing. The most devastating situation occurs when the grass blades and the upper one-half to one inch of soil has thawed, but the ground beneath their level remains frozen. Traffic will create a shearing action of the roots, rhizomes, and crown tissues at this time. This is comparable to cutting the plant tissue from the underlying root system with a sod cutter. Complete kill of leaves, crowns, and rhizomes can occur if the temperatures soon drop below 20° F. Symptoms from this severe injury include whitish to dark brown leaves that may mat on the surface.

Once temperatures allow thawing to a depth of three to four inches, the probability of turf damage declines since about 75 percent of the root system is in the upper four inches of soil. Frequently soil probing is the only positive way to effectively monitor the freezing level. Traffic should be adjusted accordingly."

Again, we are currently experiencing the conditions that will result in the most severe damage with only the top 1/2" thawing during the daytime.  

Protecting, not over-protecting, your greens is our #1 responsibility and we will continue to ensure any unnecessary damage is avoided so that they remain healthy.