Materials and Methods
Sampling locations were selected on the basis of high traffic intensity and congested crosssection. Figure 1 shows the identified heavy traffic roads and cross-sections in Chandigarh.
Table 2 depicts the location details of the selected sampling sites.
3.1 CO Monitoring
CO field monitoring was conducted for one hour (5 pm to 6 pm) of evening rush during
January to March 2011. Pulsar single gas detector (Mine Safety Appliances, USA), were used
to record the ambient CO concentrations. Rapid bump test gives results in 15 seconds interval
with alarm level of 35 ppm and 100 ppm.
3.2 Traffic volume in terms of PCU
One of the fundamental measures of traffic on urban roadway is expressed in vehicle per hour
or vehicles per day. The flow of traffic is not homogeneous. The unrestricted mixing of
different classes of vehicles in the traffic stream forms the mixed traffic flow on the roads.
The different vehicle classes have a considerable difference in their vehicular and flow
characteristics, therefore each class of vehicle in the traffic stream cannot be consider
equivalent to any other vehicle class. This makes mixed traffic flow characteristics very much
complex when compare to homogeneous traffic consisting passenger cars only. Peak hour
traffic volume was measured in terms of equivalent passenger car units (PCU) as per the
procedure prescribed in IRC (1990)