Geographic file containing the base line layer is brought on to the GIS platform; road layer is activated to be the current layer. Traffic assignment by User Equilibrium (UE) method has been performed on the network, using matrix files, attribute data linked with the map file and the planning-traffic assignment tool. The key behavioural assumptions underlying the user equilibrium assignment model are that every traveller has perfect information concerning the attributes of the network alternatives. A consequence of the UE principle is that all used paths for an O-D pair have the same minimum cost. This assumption is suitable for traffic assignment. The assigned traffic flow on the network is shown thematically in figure 3.
Analysis of results for design of interchange
Output from Transit Assignment and Mode Choice Model stages are mainly analysed to fulfil the objectives like identifying the potential location as interchange, to make policy related decisions regarding the interchange facilities and to give the design guidelines for an ideal interchange.
Analysis of Results from Mode Choice Model
The mode choice model was developed for two mode types: PT and PV. The utility functions developed in mode choice model are used and nested logit model has been applied to find the modal share of these modes. The modal share for the present scenario and for other scenarios considered for development of metro station is an interchange as given in Table 1.
Scenario – 1 in the table shows the present condition of Delhi, where the mode share between PT and PV is 64.34. Other scenarios are developed by changing the parking cost and OVTT of PT mode. In scenario – 2, the OVTT is subtracted with transfer wait time and transfer walk time which increased the PT share by 2%. In scenario – 3, the OVTT is further subtracted with 50% of access and egress walk times and the mode share of PT increased by 6% in comparison to present condition. In scenario – 4, the OVTT has been considered to be zero and the modal share increased to 77%. In scenario – 5, the parking cost has been taken as `.0/-, which increased the modal share to 70%. In scenario – 6, both the parking cost and OVTT are considered to be zero, which increased the modal share to very high value of 81%.
From this analysis, it can be seen that the modal share of PT mode in both scenarios 3 & 5 is 70%. When scenarios 4 & 5 are compared, the modal share is very high when the OVTT is reduced, rather than the scenario when free parking is provided.
The OVTT and transfer time can be reduced by improving the access and egress facilities, transfer facilities and providing park & ride facilities at public transport stations. The access & egress time and transfer time can be reduced by bringing together different modes at one location called interchange. In Delhi, the different modes that have to be brought at one interchange location are Metro Rail, DTC bus, IPT and PV. Of these, Metro Rail, a rail based transport system, is a very rigid system whereas the other modes are flexible as they are road based. So, a Metro station can be developed into an interchange station and other modes are to be brought to this station. Integration of DTC bus and Metro can be done at these locations. Other facilities like kiss-n-ride for IPT, park-n-ride for PV, etc. can be provided at this location. The transfer time can further be reduced by providing facilities like, escalator, lift for physically challenged, etc. The access and egress times can also be further reduced by providing exclusive facilities for pedestrian and bicyclists.
Analysis of Results from Transit Assignment
The various outputs from the Transit Assignment are: Flows on different routes from MP to MP, boarding and alighting on different route stops and flow, voc & cost on links from MP to MP. The flows assigned over various links of different route systems for both the horizon years are shown in figure 4. From the figure, it can be observed that the flow over metro network has increased to a large extent. This shows that there is a need for improving these metro stations with all the pedestrian and commuter facilities.
This output shows the boarding and alighting of passengers at different stops in a route system. The output data-view consists of fields like stop ID, route ID and On & Off counts. These counts are given for the peak hour. For the analysis, these counts at metro stations in both the directions are considered.
From the figures, it can be observed that the ridership is high in some important stations like Shahdara, Shastri Park, Kashmere Gate and Rithala. This analysis can be used for finding the potential metro station as a multi-modal interchange. As the ridership is high when compared with the other stations in the stations mentioned above, they have to be designed as multi-modal interchange. Facilities like access & egress and transfer facilities are to be provided at these locations to cater to the requirement of the commuter population.
This study can be used for policy making decisions. For example, if 8000 boardings are taken as the benchmark for selecting the location for interchange for the horizon year 2011, Shahdara, Kashmere Gate and Rithala are to be considered. For the horizon year of 2021, a benchmark of 12000 boardings can be taken and the stations are Shastri Park, Kohat Enclave and Pitampura. These benchmarks are assumed and can vary based on the funds available with the government.
Dr S S Jain
Professor in Civil Engineering & Head,
Centre for Transportation Systems (CTRANS)
Indian Institute of Technology, Roorkee
Ravi Kiran Rao Aluri
Delihi Integrated Multi-Model, Transit System (DIMMTS) Ltd
Dr M Parida
Professor in Civil Engineering
& Associated Faculty, CTRANS
Indian Institute of Technology, Roorkee