Safe and independent navigation of urban environments is a key feature in accessible cities. People who have physical challenges need practical, customizable, low-cost, and easily deployable mobility aids to help them safely navigate urban environments. The NavPal project focuses on designing, implementing, testing and deploying a smart mobile phone-based personalized navigation aid (NavPal) to enhance the navigation capability and hence the independence and safety of visually impaired and deafblind people. The goal of the project is to use the Android-based smart phone navigation application to assist the visually impaired and deafblind people to safely evacuate specific buildings in emergency situations. In the proposed research, my primary goal will be to combine constraint-based path planning with relevant user interface methodologies to make the planned paths accessible and relevant to visually impaired users. This work will involve conducting an initial needs assessment to understand user preference and constraints, developing and implementing appropriate route-planning algorithms, and communicating the planner routes to the visually impaired users via relevant interface modalities. Once I have implemented this work, appropriate user tests will be performed to obtain user feedback and iteratively improve the implemented system.