Global Navigation Satellite Systems (GNSS) are widely used in vehicle navigation applications. GNSS mostly suffer from atmospheric conditions and urban buildings. Due to urban buildings, GNSS signals are blocked and it is likely that the number of available satellites is insufficient to compute position fix. Classical integrity concepts do not regard local cases which appears a likely case in the vehicle navigation domain. Recent studies discuss about local integrity concept to overcome this problem in urban locations. However technical applicability using feasible resources is low. In this paper, we present a local integrity heat map that indicates possible urban canyons and estimate positioning error given the location and time of the measurement. Local integrity heat map is designed as a digital map attribute which will be used as other sensor information at the time of position sensor fusion to enhance localization and map matching. Real world field tests show that local integrity heat map is a good indicator of position fix error.