Are helmeted cyclists taking more risk at signalized intersections?

Figures & data

Figure 1. Study intersection (example; Source: Google maps, Street view).

Figure 2. Speed measurement.

Table 1. Descriptive statistics for time after red and speed, helmeted vs. unhelmeted cyclists.

	N	Mean	SD	Min.	Max.	15-percentile	85-percentile
Time after yellow (sec.)
- With helmet	558	2.483	1.562	0.000	8.508	0.867	4.101
- Without helmet	473	2.443	1.653	0.000	7.604	0.700	4.033
Speed (m/s)
- With helmet	558	6.730	1.585	2.760	11.521	5.036	8.489
- Without helmet	473	6.321	1.562	2.331	10.707	4.614	7.886

Figure 3. Mean time after yellow and speed by cyclist and intersection related variables.

Table 2. Helmet use by bicycle type and gender.

	Female		Male		All cyclists
	N	Helmet use	N	Helmet use	N	Helmet use
Ordinary bicycle	345	59%	447	43%	792	50%
Racing bicycle	20	95%	129	79%	149	81%
Mountain bike	5	80%	34	44%	39	49%
Pedelec	33	52%	8	38%	41	49%
Cargo bike	1	100%	9	33%	10	40%
All bicycles	404	60%	627	50%	1031	54%

Table 3. Linear regression models for time after yellow and speed; unstandardized coefficients for helmet use and model characteristics (N = 1031 for all models).

	Time after yellow				Speed
	Helmet only	Helmet and cyclist	Helmet and inter-section	Full model	Helmet only	Helmet and cyclist	Helmet and inter-section	Full model
Helmet use coefficient	0.040	0.018	0.024	0.010	0.409***	0.283**	0.403***	0.304***
F	0.16	4.44	25.81	16.40	17.27	23.82	71.00	54.87
df	(1; 1029)	(6; 1024)	(6; 1024)	(10; 119)	(1; 1029)	(6; 1024)	(6; 1024)	(10; 119)
p(F)	0.688	0.000	0.000	0.000	0.000	0.000	0.000	0.000
R-squared	0.000	0.025	0.131	0.150	0.017	0.123	0.294	0.372
Adjusted R-squared	−0.001	0.020	0.126	0.141	0.016	0.117	0.290	0.365
Mean square error (MSE)	2.574	2.522	2.248	2.209	2.478	2.222	1.788	1.598
Root MSE	1.605	1.588	1.499	1.486	1.574	1.491	1.337	1.264

** p < .01,

*** p < .001.