Introduction

Suburban Railway Network provides a safe, fuel-effective and time-efficient transporta- tion in congested cities. It is interesting to note that suburban rail networks in Mumbai, Kolkata and Chennai all together compose of only 7 % of track length of Indian Railways but they travel the needs of more than 50 % of total passengers. Rail Network Planning involves many problems to solve such as:

1. Line Planning: It involves the problem of figuring out the optimal railway routes over a network as per passenger demands. The problem is realised with infrastruc- tural constraints and gives the number and types of services as output.

2. Timetabling: Once the number and types of services are decided, we look to de- termine timetable for a set of trains that does not violate track capacities and satis- fies some operational constraints. Each train connects two given stations along the track and may have to stop for a minimum time at some of the intermediate stations. Trains can overtake each other only in correspondence of an intermediate station, and a minimum time interval between two consecutive departures and arrivals of trains at each station is specified. Considerations of uniformity, safety and quality of services are given importance in this step.

3. Rake-Linking: Here the problem is to realise the timetable with minimum rakes with some relaxation over uniformity of services. This step is considered crucial from econonmic perspective

4. Crew scheduling: Here we work on assigning man-power to run the network.