Various surrogate safety measures have been introduced, of which Time-to-Collision (TTC) is the most well-known and commonly applied indicator. TTC first was defined as the time remaining prior to a collision if the path and speed of vehicles are maintained as a constant. Various modifications have been applied to this indicator to increase the efficiency of TTC. However, there is still no specific platform that shows how all of these modifications can be applied simultaneously. Thus, this paper first reviews the modifications that have been made to TTC; subsequently, a comprehensive framework is proposed for the application of this indicator for different types of conflicts, while considering all previous modifications. The framework is then applied for microscopic traffic data collected in Tehran. Results indicate that there is a great difference between the results of different versions of TTC for collision probability prediction. However, the proposed procedure might be beneficial in increasing the precision and accuracy of detecting dangerous encounters.

The present study aims to evaluate public transport access distribution based on a framework of vertical equity principles. In this method, traffic analysis zones (TAZs) are analyzed by comparing the estimated transit demand with the existing geographical distribution of the network's benefits (e.g., accessibility and mobility). The framework deploys the concept of connectivity power to measure the distribution of a transit system's supply. On the other hand, demand is measured by an exhaustive index, the weighted average of four social indicators, namely the number of low-income people, the population, the households without vehicles, and the disabled in the TAZs. These weights can differ from city to city depending on culture, politics, social behavior, and costs of effective parameters such as fuel, parking, and tickets in that particular city. The framework was applied to the comprehensive transit network of Tehran, Iran. Finally, diagonal and radical lines linking the city's southwest to its northeast are proposed.

Women usually have more flexibility in time and mode choice and it might be easier to attract them to public transportation (PT) systems. In addition, in developing countries, there are limitations for women in using transportation systems. By specifying effective factors on the popularity of PT systems among women, we can pursue two objectives in developing societies. The first achievement is a decrease in traffic congestion, and the second one is reducing gender discriminations in using PT systems. This study utilized structural equation modeling (SEM) and a group of women, living in Tehran (Iran), were interviewed. Based on the results, women’s characteristics have the greatest impact on the popularity of regular bus (RB). Especially, an increase in income, education, and availability of passenger cars can significantly reduce the popularity of RB systems. For Metro and BRT, women's characteristics, fare satisfaction, and waiting time have the greatest impact on their popularity.