The court surface should be free from any imperfection that causes an inconsistent ball bounce, allows the collection of water, or significantly increases the risk of injury to players.
Undulations are measured relative to a rigid straight edge placed on the surface.
Test apparatus consists of:
- 3 m straight edge, made from box-section aluminium or equivalent.
- Wedge approximately 25 mm wide and 200 mm long, with marked height increments of 1 ± 0.25 mm.
- Two supports for the straight edge, of equal height ± 0.25 mm.
Devices used for evenness measurements should be calibrated annually. Surveying-quality straight edges in serviceable condition are deemed appropriate. The straight edge can be checked by hanging a plumb line against the bottom edge. The wedge increments and supports can be measured using a calliper, calibrated against a known standard. Check for any damage to the straight edge and wedge prior to testing.
1. Lay the straight edge on the surface, parallel to the net, and look for deviations that warrant measurement, i.e. which exceed the recommended limit in Table 4.
2. If there are any hollows, measure the point of maximum deviation from the underside of the straight edge using the graduated wedge (see Figure 5). Ensure that the straight edge is resting on the court surface either side of the hollow.
3. If there are any isolated bumps or ridges, suspend the straight edge above the peak of the bump using supports at either side (see Figure 5). Measure the point of minimum deviation from the underside of the straight edge using the wedge and subtract this value from the height of the supports. This gives the height of the bump.
4. Measure the length of the deviation by moving the straight edge either side of the maximum point, parallel to the net, until the deviation no longer exceeds the recommended limit in Table 4.
5. Move the straight edge to an adjacent location and repeat steps (1) to (4), making sufficient measurements to inspect the Total Playing Area (TPA) of the court (see Figure 4).
6. Repeat steps (1) to (5) with the straight edge at right angles to the net.
Figure 4. Plan view of a court showing recommended locations for measuring slope and planarity. All dimensions are given in metres.
a. The points A1, A7, I1 and I7 define the perimeter, which is typically kerbed.
b. The Total Playing Area (TPA) is defined by B2, B6, H2 and H6, which are located 1 m inside the perimeter of the court. Where there is no perimeter, these points will be halfway between the court being measured and the neighbouring court, or 7.5 m wide of the middle of the net (whichever is the greater).
c. The Principal Playing Area (PPA) is 15.0 m wide (parallel to the net) and 30.0 m long. The middle of the net shall coincide with the centre of the PPA. The PPA is defined by C3, C5, G3 and G5.
Figure 5. Schematic of method for measuring a hollow or a bump or ridge.
Calculation of results
Record the location, magnitude and direction (bump or dip) and orientation of all deviations outside the recommended limits. If any such deviation occurs in both test directions (parallel to and at right angles to the net), it should only be counted once. Deviations exceeding 1 m in length shall be counted per metre, or part thereof. For example a deviation (above the recommended limit) 2.5 m long shall equate to three deviations. The test value is the number of deviations outside the recommended limits for the surface type.
Refer to Table 4.
Table 4. Evenness, slope and planarity recommendations for a tennis court.
Notes: PPA = Principal Playing Area; TPA = Total Playing Area.
1. Specifications are for porous constructions. For impervious constructions, see ‘acrylic’.
2. In no instance should any imperfection exist that could cause the ball to deviate significantly from its path on a level surface, or expose a player to a significantly increased risk of injury within the perimeter of the court.
3. Deviations on clay or grass over 6 mm should be corrected where possible.
4. Unless design, specification or construction necessitate otherwise.