Study on the Annual Reduction Rate of Vehicle Emission Factors for Carbon Monoxide: A Case Study of Urban Road Tunnels in Shenzhen, China

Table 6

Average vehicle CO emission factors (unit: g/(km·veh).

Category	Henglongshan Tunnel		Cejiexian Tunnel		Jiuweiling Tunnel		Dameisha Tunnel
	Left bore	Right bore	Left bore	Right bore	Left bore	Right bore	Left bore	Right bore
Average	1.241	0.909	1.022	1.467	4.416	3.892	2.765	0.713
Standard deviation	0.512	0.277	0.650	0.468	1.348	1.264	1.239	0.311
Minimum	0.515	0.474	0.680	0.874	2.357	2.527	1.166	0.309
Maximum	2.954	1.951	4.190	2.831	8.072	9.268	6.531	1.703
Sample number (group)	50	50	50	50	50	50	50	28