Empirical Study of Travel Time Estimation and Reliability

Table 2

Errors between estimation of normal distribution and other distributions.

	8:00–8:15				8:15–8:30
	𝑇 (average travel time); (seconds)	Error 𝛿1	𝜎 (standard deviation of travel time)	Error 𝛿2	𝑇 (average travel time); (seconds)	Error 𝛿1	𝜎 (standard deviation of travel time)	Error 𝛿2
Normal distribution	46.587	—	31.803	—	47.688	—	34.109	—
Log-normal distribution	45.593	2.18%	29.036	9.53%	46.592	2.35%	31.789	7.30%
Gamma distribution	46.587	0	28.03	13.46%	47.688	0	30.241	12.79%
Weibull distribution	47.143	1.18%	29.891	6.40%	48.257	1.18%	31.988	6.63%
	8:30–8:45				8:45–9:00
	𝑇 (average travel time); (seconds)	Error 𝛿1	𝜎 (standard deviation of travel time)	Error 𝛿2	𝑇 (average travel time); (seconds)	Error 𝛿1	𝜎 (standard deviation of travel time)	Error 𝛿2
Normal distribution	73.982	—	32.15	—	56.626	—	28.849	—
Log-normal distribution	75.431	1.92%	43.737	26.49%	56.929	0.53%	33.011	12.61%
Gamma distribution	73.982	0	36.347	11.55%	56.626	0	29.279	1.47%
Weibull distribution	74.214	0.31%	30.92	3.98%	56.964	0.59%	28.201	2.30%