The RADS Page

RADS : The Route ADvisory System (1997-2002)
Leong Hon Wai,
School of Computing, NUS.

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RADS -- Route ADvisory System

RADS is short for Route ADvisory System. RADS was a research and development project led by Prof. Leong Hon Wai of the School of Computing (SOC), of the National University of Singapore (NUS). The development of RADS and its associated enhancements and related research spanned five years 1997-2002 and involved many students, many of them undergraduates of NUS School of Computing.

The RADS system enables Singapore commuters to plan the best route on all public transportation (all buses and subway) between any two points in Singapore. RADS has many innovative features that distinguishes it from other route planning systems. For example, RADS


Versions of RADS

At the moment, RADS comes in several options:
  1. Windows stand-alone application,
  2. experimental web-based service with simple text output,
  3. experimental WAP-based service activated via Phone emulator.

Windows stand-alone version:
The Windows version of RADS come integrated with a rudimentary GUI-driven GIS/map interface to view a (skeletal) map of Singapore with partial mockups with several landmarks and several major roads for demo purposes. It also shows the locations of all the bus stops (as of about 2001). (This research project did not have the funding to support the purchase of the Singapore digital map data from SLA.) The RADS GUI/GIS supports some of the basic GIS functions like zooming, panning. This GUI of the Windows version of RADS

Web and WAP versions:
These versions are experimental trials that deploy the route planning engine for the web and wap. Both versions do NOT come with digital maps. A research server in the NUS School of Computing is used to provide this experimental route planning service for web/wap. This server receives the start/end points and planning preferences and will compute the planned route, and return the planned route in xml/wml formats.

For the web version of RADS, the user will have to hand code the locations of start and end points and the planning preferences, to be submitted to the server. (Note: A web form can be created to simplify this process a little.)

In the WAP version of RADS, we make use of a WAP phone emulator that provide simple GUI-like features to select start and end points and planning preferences. The planned route is returned in wml that is displayed on the emulated phone. The output comes in three levels of details. The default is very brief desciption of the route: bus service, MRT stops. The intermediate level (activated by choosing "more" of the phone) shows more details of bus-stops. Finally the verboise level gives a lot of details bus/MRT service to take, the stops/stations to board and where to alight, and so on.

Scalability Issues:
Extensive performance benchmarking has been performed on this experimental route planning service in order to ensure scalability of this web service.

(Note: Because research funding for this project has ended, this RADS web service is turned off (by default). But it can be re-activated if there is a special request.)


Note 2: (Added in 2008)

The RADS web service is coming alive again. In collaboration with IDA, RADS will be provided as a web-service, codenamed the IDA-NUS Free Trial RADS Service. IDA will work it her partners to provide a Web 2.0 Google Map interface for all web-users to select their travel plan (source, destination, preferences, etc) while the route planning and optimization will be done by the RADS web-service of our group.

For early preview of things, please view the following


Key Technologies used in RADS

While the problem of finding a bus/MRT route between two bus stops is a relatively trivial algorithmic problem, it solves only the static problem (namely, is there a route between these two points). In fact, this problem can/should be better solved via pre-computation of the routes and then doing a table look-up.

However, to find an optimal route for different user preferences and that integrates walking time, and waiting time at the bus stop is a more complex optimization problem and requires considerably more sophisticated algorithms. In fact, RADS can also take advantage of real-time arrival schedule information to give up-to-date real-time optimal routes.

The key technologies developed by the research group and deployed in RADS is a novel route optimization engine that we call RADS-MM. The RADS-MM route optimization engine incorporates an algorithm that computes shortest travel plan using public transportation (buses and MRT). Technically, the RADS-MM route optimization engine solves a dynamic multi-modal, multi-criteria shortest path problem.


Other RADS-related Development Efforts:

There are other R&D efforts that are related to RADS, but are either less matured or have not been integrated into the RADS system. We list some of them here for information (and in case other parties are interested in them).


Acknowledgements and Credits:

The research and development of RADS span many years (1997 to 2002) and is the combined efforts of many of my students who have worked on different parts of RADS. They includes: Foo Hee Meng (past project manager role), Lao Yizhi (RADS-MM), Lam Nah Peng (RADS-Dyn), David Ong (project manager for RADS-GUI and RADS-GIS), Desmond Kao, Esther Choa, Stevenas (RADS-GUI), Li Qiming, Liang Zhe, Sun Guangyu (RADS-GIS), Michael Teo (RADS-Web), Ho Ngai Lam, Francis Ng Hoong Kee (RADS-PS), Yuan Yi, Yong Chin Loung, Hu Xiao (RADS-GUI2), Gokul Poduval, Sharma Vikas, Ngai Nyuk Lan, Dorothy (RADS-WAP), Phan Thi Xuan Linh (RADS-CAR), Tan Meng Mau, Guan Bo, Hieu (data), Kal Ng Yen Kaow (various assorted enhancements).


| Leong Hon Wai | Dept of Computer Science | School of Computing | NUS |
(Started: Jan 2002, Updated: July 2008)

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