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

Figure 3

The sampling point distribution in the four tunnels. (a) Henglongshan Tunnel. (b) Cejiexian Tunnel. (c) Jiuweiling Tunnel. (d) Dameisha Tunnel.

(a)

(b)

(c)

(d)