Lawson Wind Comfort Criteria

The Lawson Pedestrian Wind Criteria is a globally-accepted standard used to assess wind impacts on pedestrian safety and comfort. In general, strong winds and wind gusts can negatively impact the pedestrian experience and may even pose a safety risk. 

Pedestrian Wind Comfort Criteria aim to classify different areas by the activities pedestrians may tolerate under predicted wind conditions. In essence, pedestrians can tolerate different strengths of wind depending on their activity. A runner, for instance, may tolerate or even enjoy a moderate breeze; on the other hand, diners enjoying a meal on a patio may find that those same winds detract from their dining experience. 

The Lawson Criteria characterizes wind conditions by the Gust Equivalent Mean (GEM), an adjusted wind speed calculated from average hourly wind speeds (steady-state) and wind gusts (spontaneous). These speeds are based on an analysis of all 24 hours of the day across all four seasons. Comfort categories are defined such that the GEM must remain below the category threshold at least 95% of the time (see table below). 

Activity Description GEM Speed (mph) GEM Speed (kph) GEM Speed (m/s)
Sitting Calm or light breezes. Ideal for outdoor dining and seating areas where one can read a paper without having it blown away. ≤ 9 ≤ 14.5 ≤ 4
Standing Gentle breezes. Acceptable for building entrances, bus stops, and other places where pedestrians may linger. ≤ 13.5 ≤ 21.5 ≤ 6
Strolling Moderate winds. Acceptable for window shopping or leisurely strolls across a park or plaza. ≤ 18 ≤ 29 ≤ 8
Walking (Includes Running/ Cycling) Relatively strong winds. Tolerable for brisk walking, jogging or cycling. ≤ 22 ≤ 36 ≤ 10
Uncomfortable Too windy for any normal pedestrian activities. A more in-depth wind analysis study might be necessary. > 22 > 36 > 10
Safety Criterion Description GEM Speed (mph) GEM Speed (kph) GEM Speed (m/s)
Dangerous (Frequent Pedestrian) Strong winds which discourage pedestrian activity. Mitigation is typically recommended. > 33.5 > 54 > 15
Dangerous (Infrequent Pedestrian) Extremely strong winds / gusting which pose a safety risk to pedestrians. Mitigation is typically required. > 45 > 72 > 20

Analysis Criteria – Supplemental Information

  • Hours of the Day: All
  • Seasons: All
  • Allowed Exceedance (Comfort): 5%
  • Allowed Exceedance (Safety): 0.022%

Want to speak to an Expert Wind Consultant?

Schedule a one-hour consultation session with an expert from RWDI to explore potential mitigation strategies and gain insights in the event the wind speeds at your site deviate from the intended activity.

Please reach out to your Account Manager or email sales@orbitalstack.com to book your session today!