Investigation of factors affecting turn signal usage at modern roundabouts in State of Qatar

Figures & data

Figure 1. Layout of selected roundabouts. (a) Izghawa roundabout, (b) Al-Khebra roundabout, (c) Al-Meera roundabout, (d) Aspire roundabout.

Table 1. Characteristics of selected roundabouts.

Site			Na	Dic (m)	Dci (m)	Ne
	Approach	Nc				North	East	South	West	North-West
Izghawa	North	2	4	52	35	2	2	2	1	-
Al-Khebra	South	2	3	43.5	26.5	-	2	2	2	-
Al-Meera	North	3	4	95–60	112–82	3	3	3	3	-
Aspire	West	3	5	95	70	1	3	2	1	2

N_c is number of circulating lanes, N_a is number of approaches, D_ic is inscribed circle diameter, D_ci is Central Island diameter, N_e is number of entry/exit lanes.

Table 2. Rate of signal use while entering roundabouts.

Parameter	nv	nvu	Rate (%)	95% CI	χ2	p	Φ
Overall	830	267	32.2	29.0–35.4
Turn type					31.829	<.001	0.196
Left	297	111	37.4	31.8–42.9
Right	206	51	24.8	18.8–30.7
U-Turn	146	67	45.9	37.7–54.1
Straight	181	38	21.0	15.0–27.0
Correct lane					8.973	.003	0.104
Yes	672	232	34.5	30.9–38.1
No	158	35	22.2	15.6–28.7
Roundabout type					33.287	<.001	0.200
Small	416	95	22.8	18.8–26.9
Large	414	172	41.6	36.8–46.3
Vehicle type					23.117	<.001	0.167
Sedan	236	68	28.8	23.0–34.6
SUV	133	49	36.8	28.5–45.2
Luxury	286	71	24.8	19.8–29.9
Professional	175	79	45.1	37.7–52.6
Following vehicle					0.615	.433
Yes	191	57	29.8	23.3–36.4
No	639	210	32.9	29.2–36.5
Gender					0.008	.929
Male	741	238	32.1	28.8–35.5
Female	89	29	32.6	22.7–42.5
Age					10.336	.006	0.112
Young	179	40	22.4	16.2–28.5
Middle	612	212	34.6	30.9–38.4
Elder	39	15	38.5	22.5–54.4
Type of clothes					26.022	<.001	0.177
Formal	76	41	54.0	42.5–65.4
Casual	569	186	32.7	28.8–36.6
Traditional	185	40	21.6	15.6–27.6
Accompanied					0.274	.601
Yes	248	83	33.5	27.6–39.4
No	582	184	31.6	27.8–35.4
Distraction					23.969	<.001	0.170
Yes	162	26	16.1	10.3–21.8
No	668	241	36.1	32.4–39.7
Lane change					2.428	.119
Yes	46	10	21.7	9.4–34.1
No	784	257	32.8	29.5–36.1

n_v is the number of vehicles observed, n_vu is the number of vehicles using turn signal.

Table 3. Rate of signal use while exiting roundabouts.

Parameter	nv	nvu	Rate (%)	95% CI	Chi-square	p-value	Phi
Overall	830	293	35.3	32.0–38.6
Turn type					32.029	<.001	.196
Left	297	116	39.1	33.5–44.6
Right	206	56	27.2	21.7–33.3
U-Turn	146	75	51.4	43.2–59.6
Straight	181	46	25.4	19.0–31.8
Correct lane					13.209	<.001	.126
Yes	679	259	38.1	34.5–41.8
No	151	34	22.5	15.8–29.3
Roundabout type					105.929	<.001	.357
Small	416	76	18.3	14.5–22.0
Large	414	217	52.4	47.6–57.3
Vehicle type					18.052	<.001	.147
Sedan	236	77	32.6	26.6–38.7
SUV	133	51	38.4	30.0–46.7
Luxury	286	82	28.7	23.4–33.9
Professional	175	83	47.4	40.0–54.9
Following vehicle					4.392	.036	.073
Yes	265	107	40.4	34.4–46.3
No	565	186	32.9	29.0–36.8
Gender					0.019	.891
Male	741	261	35.2	31.8–38.7
Female	89	32	36.0	25.8–46.1
Age					12.500	.002	.123
Young	179	44	24.6	18.2–31.0
Middle	612	237	38.7	34.9–42.6
Elder	39	12	30.8	15.6–45.9
Type of clothes					27.530	<.001	.182
Formal	76	46	60.5	49.3–71.8
Casual	569	198	34.8	30.9–38.7
Traditional	185	49	26.5	20.1–32.9
Accompanied					3.357	.067
Yes	248	76	30.7	24.9–36.4
No	582	217	37.3	33.4–41.2
Distraction					18.056	<.001	.147
Yes	162	34	21.0	14.7–27.3
No	668	259	38.8	35.1–42.5

n_v is the number of vehicles observed, n_vu is the number of vehicles using turn signal.

Table 4. Model predicting turn signal usage at roundabouts.

Parameter	While entering the roundabout						While exiting the roundabout
	β	SE	p	OR	95% C.I.		β	SE	p	OR	95% C.I.
					Lower	Upper					Lower	Upper
Clothing*			<0.001						<0.001
Formal	0.618	0.266	0.020	1.855	1.102	3.124	1.039	0.283	<0.001	2.826	1.624	5.917
Traditional	−0.742	0.216	<0.001	0.476	0.312	0.728	−0.642	0.213	0.003	0.526	0.347	0.799
Turn Type^#			0.008						<0.001
Straight	−0.454	0.276	0.101	0.635	0.370	1.092	−0.660	0.267	0.014	0.517	0.306	0.873
Left	0.035	0.233	0.879	1.036	0.656	1.636	−0.007	0.239	0.976	0.993	0.622	1.585
U turn	0.478	0.259	0.065	1.613	0.971	2.681	0.594	0.270	0.028	1.812	1.066	3.079
Correct lane^^
Yes	0.553	0.228	0.015	1.738	1.113	2.716	0.631	0.245	0.010	1.879	1.162	3.038
Distracted^~
Yes	−1.069	0.242	<0.001	0.343	0.214	0.552	−0.784	0.230	<0.001	0.457	0.291	0.716
Surrounding land use^$			<0.001						<0.001
Residential & commercial	−0.539	0.225	0.016	0.583	0.376	0.905	−0.407	0.221	0.066	0.666	0.431	1.027
Educational	−0.714	0.221	0.001	0.490	0.318	0.756	−1.846	0.249	<0.001	0.158	0.097	0.257
Residential	−1.789	0.280	<0.001	0.167	0.097	0.289	−1.874	0.270	<0.001	0.154	0.091	0.260
Constant	−0.281	0.338	0.405	0.755			−0.003	0.361	0.994	0.997
− 2 Loglikelihood = 907.607 %		% correctly predicted = 72.4					− 2 Loglikelihood = 887.060			% correctly predicted = 71.3
Chi Square = 12.292		Nagelkerke R^2 = 21.0%					Chi Square = 7.936			Nagelkerke R^2 = 28.2%

* indicates Casual as Reference case, # indicates Right as Reference case, ^ indicates No as Reference case, ~ indicates No as Reference case, $ indicates Commercial & recreational as Reference case.

Table

		Driver turn signal use while entering roundabouts
Roundabout name:
Street Name:						Coordinates:			Area:
No of lanes			RT		LT		TH		Type of control:
Advance warning signs (Y/N)
Date:						Time From: to			Traffic patrol (Y/N)
Weather						Peak/off peak
Choose a vehicle when its at around 300-400 m distance from roundabout entry point
Collect age group wherever possible (Y-Young <25, M-Middle 25 to 55, E-Elder >55)
Clothing type F – Formal, C – Casual, T – Traditional
Other visible distractions can be eating, talking, etc
Vehicle type: S1, S2, V1, V2, P, H – see explaination in Variables sheet
Following vehicle type: Use same classification S1, S2, V1, V2, P, H, if no Vehicle write N
	Driver related observations						Vehicle related observations		Turn details
Vehiclenumber	Gender (M/F)	Age group (Y, M, E)	Accompanied (Y/N)	Clothing type (C, F, T)	Using phone (Y/N)	Other distraction (Y/N)	Vehicle Type (S1, S2, V1, V2, P, H)	Following vehicle type (S1, S2, V1, V2, P, H, N)	Turn type (L, R, U)	Correct lane used (Y/N)	Lane change (within 300 m distance) (Y/N)	Indicator used (Y/N)
1
2
3
4
5

Table

Gender	Age group	Accompanied	Clothing type	Using phone	Other distraction	Vehicle Type	Following vehicle	Turn type	Lane used	Lane change (within 300 m distance) (Y/N)	Indicator used
Male	Y-Young <25	Y	F – Formal	Y	Y	S1	Y	L	Y	Y	Y
Female	M-Middle 25 to 55	N	C – Casual	N	N	S2	N	R	N	N	N
	E-Elder >55		T – Traditional			V1		U
						V2
						P
						H
S1	Sedan T1	High end Sedan cars like mercedes, BMW, volvo, audi, lexus, infinity, sports cars, etc
S2	Sedan T2	Normal sedan cars like toyota, mitsubishi, Nissan, Kia, Honda, Hyundai, etc
V1	SUV T1	High end four wheel drives like Lexus, Land cruiser, Mercedes, BMW, range rover, land rover, etc
V2	SUV T2	Normal four wheel drives like Kia, Mitsubishi, etc
P	Professional	Karwa taxi, Vans, pickups, limosine etc
H	Heavy	Trucks, trailers, mini buses, buses, etc