Speed Study Calculator

Type of Study (using the lower value from ITE to provide greater accuracy)

Transportation Planning and Highway Capacity Studies Traffic Operations Trend Analysis Economic Evaluations Before and After Studies Distance of segment (miles): Elapsed times for each run (seconds, comma-separated): Calculate Speeds

Results

Minimum Sample Size Requirements for Travel Time and Delay Studies (95% confidence)

Average Range in Running Speed, R̄ (mph)	Minimum Number of Test Runs, Nᵼ, for a Permitted Error of
	1.0 mph	2.0 mph	3.0 mph	4.0 mph	5.0 mph
2.5	4	3	2	2	2
5.0	8	4	3	3	2
10.0	21	8	5	4	3
15.0	38	14	8	6	5
20.0	59	21	12	8	6