Assessing the impact of converting roundabouts to traffic signals on vehicle emissions along an urban arterial corridor in Qatar

Figures & data

Figure 1. VISSIM MOVES integration process.

Figure 2. Turning movement count data for the corridor.

Table 1. Intersections and roadway segments in the before and after conditions.

Intersections	Before/after conditions
Al Corniche St @ Asmakh St	Roundabout 1 (RA1)/Intersection 1 (Int1)
Al Corniche St @ Moh Bin Thani St	RA2/Int2
Al Corniche St @ Markhaya St	RA3/Int3
Al Corniche St @ Funduq St	RA4/Int4
Roadway segments	Before conditions
South of RA1	Link 1 (L1)
Roundabout1	RA1
From RA1 to RA2	L2
Roundabout2	RA2
From RA2 to RA3	L3
Roundabout3	RA3
From RA3 to RA4	L4
Roundabout4	RA4
North of RA4	L5
Roadway segments	After conditions
South of Int1	L1
Int1 approach (LT & TH)	L11
Int1 (LT & TH)	Int1
From Int1 to Int2	L2
Int2 approach (LT & TH)	L21
Int2 (LT & TH)	Int2
From Int2 to Int3	L3
Int3 approach (LT & TH)	L31
Int3 (LT & TH)	Int3
From Int3 to Int4	L4
Int4 approach (LT & TH)	L41
Int4 (LT & TH)	Int4
North of Int4	L5

Figure 3. (a) VISSIM screenshot showing the corridor layout. (b and c) VISSIM screenshot showing (b) the before case (roundabout) and (c) the after case (signalized intersection).

Table 2. Emissions by control type, link, pollutant, and source type.

	Link			CO emissions (kg)		NOx emissions (kg)		CO2 emissions (kg)
Source type	RA	Signals	Length (mile)	RA	Signals	RA	Signals	RA	Signals
Passenger car—gasoline	L1	L1	0.18	6.57	2.97	0.59	0.21	688.67	227.59
		L11	0.13		5.09		0.29		281.01
	RA1	Int1	0.04	1.56	1.81	0.13	0.09	164.03	76.76
	L2	L2	0.94	53.46	14.44	3.34	1.15	3424.57	1282.04
		L21	0.19		7.52		0.45		467.48
	RA2	Int2	0.04	1.51	1.70	0.12	0.08	139.14	73.42
	L3	L3	0.31	14.57	9.82	0.91	0.52	1014.83	499.48
		L31	0.16		5.23		0.33		347.58
	RA3	Int3	0.03	1.47	1.58	0.11	0.08	131.78	64.44
	L3	L4	0.75	18.79	9.70	1.56	0.75	2102.53	827.06
		L41	0.10		2.25		0.16		199.73
	RA4	Int4	0.04	2.20	1.78	0.16	0.08	179.43	70.70
	L5	L5	0.32	7.04	3.24	0.37	0.24	316.18	246.09
Buses—diesel (bus)	L1	L1	0.18	0.05	0.02	0.19	0.07	54.47	19.87
		L11	0.13		0.02		0.05		14.33
	RA1	Int1	0.04	0.01	0.004	0.04	0.01	12.07	3.94
	L2	L2	0.94	0.24	0.09	0.84	0.32	248.59	95.00
		L21	0.19		0.03		0.10		28.53
	RA2	Int2	0.04	0.01	0.004	0.03	0.02	9.67	4.60
	L3	L3	0.31	0.08	0.03	0.30	0.11	90.62	34.29
		L31	0.16		0.02		0.08		23.24
	RA3	Int3	0.03	0.01	0.003	0.03	0.01	9.56	3.58
	L3	L4	0.75	0.17	0.06	0.57	0.20	161.72	59.61
		L41	0.10		0.01		0.04		11.04
	RA4	Int4	0.04	0.01	0.004	0.04	0.01	12.22	4.17
	L5	L5	0.32	0.02	0.02	0.06	0.05	18.25	16.37
Total emissions			3.23	107.77	67.45	9.40	5.50	8778.32	4981.95

Figure 4. (a) CO₂, (b) CO, and (c) NO_x emissions by vehicle and control types.

Figure 5. (a) Total emissions variation on corridor links for roundabouts. (b) Emissions rates variation on corridor links for roundabouts.

Figure 6. Link operating mode distribution on selected links (L2, RA2, L3) for roundabouts.

Figure 7. (a) Total emissions variation on corridor links for intersections. (b) Emission rates variation on corridor links for intersections.

Figure 8. Link operating mode distribution on selected links (L2, L21, Int2, and L3) for (a) the through movement and (b) the left movement.