Transportation systems are designed to transport people from one place to another as safely and efficiently as possible. Unfortunately, many accidents and fatalities occur on the road every day. Recently, the development of the Intelligent Transportation System (ITS) has been advancing towards safe and smooth driving without delay. Wireless communication systems are expected to play a pivotal role in the ITS safety-related applications. The Dedicated Short Range Communication (DSRC) standard with 75 MHz at 5.9 GHz band was projected and licensed to support low-latency wireless data communications between vehicles and from vehicles to roadside units in the USA. It is being standardized as IEEE 802.11p. Vehicle safety-related communication services require reliable and fast message delivery in vehicular ad hoc networks (VANETs). The potential safety applications of DSRC require a robust dissemination of safety messages with stringent delay and reliability requirements. Research on enhancing current DSRC systems to meet the given quality of service (QoS) for safety applications is going on. In this presentation, QoS and capacity issues in VANETs for safety-related broadcast services are addressed. First, a short overview of IEEE 802.11p for ITS and challenges of VANETs for safety applications is given. Second, existing QoS metrics to characterize VANET behavior for the safety applications and analytical models for deriving the QoS metrics are summarized and compared. Then, new QoS metrics and requirements that are functions of awareness range, time window, and vehicle driving environment and direction to reflect and distinguish features of individual safety applications with higher granularity are introduced and explained. Consequently, with these new QoS metrics, current DSRC system settings or new protocols can be objectively evaluated and designed. Third, Novel analytic modeling of current VANET is conducted to quantify DSRC channel capacity for safety applications and estimate spectrum resource gap between what the current DSRC VANET could provide and what is needed for assurance of required QoS for all safety applications. Finally, some potential solutions to optimizing and improving capacity of vehicular networks for safety applications with required QoS are suggested. This research will speed up development and dissemination of next-generation cars equipped with wireless communication capability.