4. GIS Based TSM
4.1.Forecasting the Traffic
The traffic volume for the year 2002 and future year 2007 are forecasted with respect to the 1997 traffic volume taken from the CTTS Report (CTTS Report, 1997), vehicle growth rate and the sample survey conducted at different locations. However, the capacity restraints are not taken into account. The traffic volume count made at different selected locations the percentage share of each type of vehicle is computed. As per IRC: 106-1990 (IRC: 106, 1990) the PCU values are assigned and the total PCU share of each vehicle is obtained on each link. Fig. 1 shows the traffic flow in the CBD.
Based on the registered vehicle data collected from the Regional Transport Office Madurai North and South the growth rate of each type of vehicle is calculated. For the unregistered vehicles like bicycle and cycles rickshaws the growth rate was obtained through the general enquiry made at different cycle marts and cycle rickshaw unions that is mentioned in the growth rate table. For forecasting traffic on NH, SH, MDR’s overall growth rate of 12 percent is taken.
Fig. 1 Peak Hour Traffic Flow in CBD
4.2. Road Capacity Calculation
Capacity of all the links are made with three different categories:
- Capacity with parking
- Capacity with restricted parking
- Capacity without parking
The capacity of road links as per HCM 1985 is 1300-1500 PCU per lane per hour. Adopting the average value of 1400 and a lane width of 3.50 m, the capacity is computed as 400 PCU/hr per one metre effective width of carriage way.
The following formula is adopted for the calculation of capacity,
Capacity = Effective width of road way * 400 PCU/hr
To obtain the effective width of road, road inventory survey was conducted and total width (after encroachment) and parking width are measured. For the different cases the effective width is taken as,
Effective width with parking = Total width – parking width
Effective width without parking = Total width
Effective width with restricted parking = Total width – parking width allowed.
The width of parking allowed is computed by adopting the following four conditions:
4.3.Conversion of One-way Streets
|Total road width (m)
|| Parking width allowed (m)
|Less than 5 m
|>5 m and <= 10 m
|>10 m and <=15 m
|Greater than 15 m
South Veli and East Veli Streets of the CBD are identified as highly congested. They can be made as one-way streets, with the help of the parallel streets. Analysis was conducted on the peak hour volume count made during morning and evening at South Veli, East Veli, and their parallel streets South Marret and East Marret. From that the maximum peak hour composition in each direction is found out and assigned to the roads by comparing their capacities. As per the rules of Madurai Corporation buses are not permitted to operate on the inner roads within the Veli streets. It is taken into consideration and the movement of buses alone may be allowed through the Veli Street even after the conversion of those roads as one-way streets. IRC Special Publication 43 (IRC SP: 43, 1990) permits the above situation. The streets before and after the introduction of one-way streets are shown in Fig. 2 and Fig .3.
Fig. 2 Before Introduction of One-way Streets in Madurai CBD
Fig. 3 After Introduction of One-way Streets in CBD
After the conversion of the existing two-way streets to one-way streets the reduction in the V/C Ratio and improvement in the whole network was studied. By running the Avenue script and selecting the required LOS from the list, the links falling under that category will be selected. This process (LOS = A) is shown in Fig. 4.
Fig. 4 Level of Service A