HOW MUCH WILLIAMSBURG SOCCER FIELD CAPACITY WAS ADDED BY CONVERTING TO ARTIFICIAL TURF VS. HOW MUCH WOULD BE ADDED BY INSTALLING LIGHTS? OVERVIEW This analysis examined the field capacity that would be added to schedulable Arlington County fields by adding lights to the unlit turf fields at Williamsburg in comparison with the capacity already added by converting the Williamsburg grass fields to unlit turf. The analysis shows that capacity of Arlington schedulable fields has already been increased by about 10% by adding unlit Williamsburg turf fields. Adding lights to the Williamsburg fields would add incremental capacity of perhaps 1.8%, depending on the nightly and day-of-week schedules/curfews that are adopted. These figures would be even lower if the capacity of Arlington s drop-in fields were included in the analysis. The lower yield of capacity from installing lights vs. converting grass fields to artificial turf suggests that Arlington should consider adding capacity by converting more grass fields to turf rather than disrupting
neighborhoods at Williamsburg -- and other sites so close to homes -- by adding lights. THE ANALYSIS Several different sets of capacity estimates have been provided by DPR, so let s do the analysis with each of them: OPTION 1: VERBAL ESTIMATES FROM DPR On multiple occasions DPR personnel cited the following capacity measures of capacity per field: Grass field = 600 hours per field Unlit turf field = 1600 hours per field Lighted turf field = 2000 hours per field With these assumptions, converting grass to unlit turf increased capacity by 1000 hours, or an increase of 167% adding lights to unlit turf would increase capacity by 400 hours, or an increase of an additional 25% Of the 1400 hours gained by converting grass to lighted turf, 71% would have come from converting to turf, and 29% would come from adding lights
OPTION 2: ESTIMATES FROM WFWG DOCUMENTS #51 AND #52 AND THE DPR 3-20-16 ANALYSIS Williamsburg grass fields were schedulable for 580 hours per field (per DPR #51) 20% of scheduled grass field usage is lost due to inclement weather (per DPR #52) Hence, Williamsburg grass fields were usable ~464 hours per field (0.8 x 580 = 464) Lighted Williamsburg turf fields would be schedulable for 1414 hours per field with a 10pm curfew (per DPR #51) [or 1,220 hours with a 9pm curfew or 1492 hours with an 11pm curfew] While DPR did not provide a number of schedulable hours for unlit Williamsburg turf fields, it can be deduced from the DPR 3/20/16 analysis, which shows that an unlit synthetic field has 73.6% of the available capacity of a lighted synthetic field with a 10pm curfew [4018 hours /5460 hours = 0.736] Therefore, the schedulable availability of an unlit turf field can be estimated as 0.736 x 1414 hours = 1,040 hours per field
Consequently, the usable hours for the various types of fields can be estimated as: Grass field = 464 hours per field Unlit turf field = 1040 hours per field Lighted turf field = 1220 hours per field (9pm curfew) = 1414 hours per field (10pm curfew) = 1492 hours per field (11pm curfew) With these assumptions, converting grass to unlit turf increased usable capacity by 576 hours or 124% adding lights to unlit turf with a 9pm curfew would increase usable capacity by 180 hours or an additional 17%. adding lights to unlit turf with a 10pm curfew would increase usable capacity by 374 hours or an additional 36%. adding lights to unlit turf with an 11pm curfew would increase usable capacity by 452 hours or an additional 43%.
HOW SIGNIFICANT WOULD ADDED CAPACITY FROM LIGHTING WILLIAMSBURG FIELDS BE? The analysis shows that Arlington has already received the lion s share of added capacity just by converting Williamsburg s grass fields to synthetic turf. That leaves the question of how much of a difference the additional capacity from lighting the Williamsburg fields would make in addressing Arlington s field capacity. Not counting Williamsburg, Arlington currently has the following schedulable fields: 22 grass fields, 8 lit turf fields (including Wakefield and Washington-Lee) 1 lit turf field (Kenmore) not used at night In addition, there are additional non-scheduled ( drop-in ) fields (e.g., Thomas Jefferson Park, a lighted turf field) that are not included in this capacity analysis. Using Option 1 (verbal estimates from DPR of 600 hrs. for grass, 1600 for unlit turf, and 2000 for lighted turf), Arlington had schedulable fields with actual capacity of (22 x 600) + (8 x 2000) + (1 x 1600) = 13,200 + 16,000 + 1600 = 30,800 hours of capacity before adding Williamsburg
Williamsburg currently has 2 unlit turf fields with capacity = 2 x 1600 = 3,200 hours. So the current Williamsburg fields have added 3,200/30,800 = 10.4% to Arlington s schedulable field capacity available in 2014-15. Lighting the Williamsburg fields would add 2 fields x (2000 1600) = 2 x 400 = 800 hours of capacity, thereby increasing Arlington field capacity by 800/(3,200 + 30,800) = 800/34,000 = 2.3% incremental capacity. We do not know for sure whether these DPR capacity estimates assume any curfew, but since they are much more than the estimates derived from Option 2, it is reasonable to assume that they do not include any curfews or reduced schedules. If not, curfews/schedules would likely reduce incremental capacity added by lights to somewhere in the range of a 1-2% capacity increase. Using the Option 2 estimates for the same analysis (464 playable hours for grass, 1040 hours for unlit turf, and 1,220 hours for lit turf with a 9pm curfew, 1,414 with a 10pm curfew, and 1,492 with an 11pm curfew, Arlington has schedulable fields with actual capacity of (22 x 464) + (8 x 1492) + (1 x 1,040) = 10208 + 11936 + 1040 = 23,184 hours of capacity before adding Williamsburg fields.
Williamsburg s 2 unlit turf fields have capacity of 2 x 1040 using the Option 2 estimates = 2,080 hours. So the current Williamsburg fields have added 2,080/23,184 hours of capacity = 9.0% to Arlington s schedulable field capacity available in 2014-15. Lighting the Williamsburg fields would add 2 fields x (1492 1040) = 2 x 452 hours = 904 hours with an 11pm curfew. A 10pm curfew, would add 748 hours, and a 9pm curfew would add 360 hours. So an 11pm curfew would increase capacity by 904/(23184 + 2080) = 904/25264 = 3.6%. A 10pm curfew would increase capacity by 3.0%, and a 9pm curfew would increase capacity by 1.4%. Using the Sample Schedules and the Mitigation steps presented in the DPR January 19, 2016 Field Usage Analysis report to the WFWG for guidance on what schedules might be adopted for the Williamsburg fields by season (which include varying end times and some evenings not utilized by season), the average completion time for field usage across the days and seasons appears to be between 9pm and 10pm, averaging about 9:16pm. This suggests an increase of capacity of about 1.8% due to use of lights if the DPR Sample Schedules were followed using Option 2 assumptions.
CONCLUSIONS The gain in field capacity (about 9% to 10.4%) from adding the two Williamsburg artificial turf fields has been much greater than would be the additional gain in capacity from lighting the two fields in the future, especially considering the effect of any likely schedule, curfew, or underutilization on use of that capacity. The additional gain in capacity from lighting the fields would yield only a small further increase (perhaps 1.8% or less) in overall Arlington field capacity, with the increase dependent on what nightly and day-of-week curfews are adopted. Most of the potential gain from lighted turf has already been accomplished by adding the unlit artificial turf fields at Williamsburg. The remaining questions (to be answered by the WFWG and ultimately the County Board) are: Is it worth the impact on (1) character of the neighborhood, (2) effects on the health and sleep of the players, coaches, referees, and neighbors and (3) effects on community wildlife to gain such marginal additional field capacity for Arlington?
Would it be more cost efficient for Arlington and less disruptive for neighbors at Williamsburg (and at future candidate sites for adding lights) to devote Arlington resources to converting existing grass fields to artificial turf rather than spend money on lights that disrupt communities for relatively small gains in usable field capacity?