Update README.md with general information about ABM and refer to documentation website

Author: bhargavasana

README.md

@@ -1,15 +1,30 @@
-ABM
+SANDAG ABM
 ===
 
-How to Build the Sandag ABM Java Programs
+Welcome to the San Diego Association of Governments (SANDAG) Activity-Based Model (ABM) code repository!
 
-  - Download Eclipse
-  - Install Maven (m2e) if needed (check if it is already installed via Windows + Preferences)
-  - File + Import + Maven + Existing Maven Projects and select pom.xml
-  - Eclipse will import the SANDAG ABM maven project, which includes downloading the dependencies from SANDAG's svn server
-  - Right click pom.xml and select Run As + Maven with the goal `clean package` and check "skip tests"
-  - The outputs are here: target\SANDAG CT-RAMP Activity Based Model
+### Overview
+The SANDAG ABM is a sophisticated transportation modeling tool that simulates individual and household travel behavior throughout the San Diego region. It captures a wide range of daily travel activities — including commuting to work or school, shopping, accessing healthcare, and recreation — by modeling the decisions that drive those trips.
 
-Dependencies are download to Windows + Preferences + Maven + User Settings + Local Repository.  Make sure you have access to SANDAG's SVN and Nexus servers (via VPN with the Nexus port open).
+### What is Modeled
+The ABM accounts for a variety of weekday travel markets, including:
+- **Resident travel** within the San Diego region
+- **Cross-border travel** of Mexico residents traveling into the region
+- **Visitor travel** of overnight visitors within the region
+- **External travel** of non-residents crossing San Diego County’s borders
+- **Airport passenger travel** convering:
+  - San Diego International Airport
+  - Cross Border Xpress (CBX) bridge to Tijuana International Airport
+- **Commercial and freight travel**
 
+### Purpose and Application
+The SANDAG ABM plays a critical role in regional planning and policy development. It supports the creation of the Regional Plan, helping transportation planners and policymakers:
+- Evaluate the performance of transportation projects
+- Analyze the impacts of proposed policies
+- Support data-driven decision-making on complex mobility issues in the region
+
+### Documentation
+For detailed information on how the model works, including setup instructions and technical specifications, please refer to the full documentation:
+
+[SANDAG ABM Documentation](https://sandag.github.io/ABM/)