Review on high occupancy vehicle lane: Istanbul case study

Demographically, Istanbul is known as the metropolitan and business hub of Turkey. However, it has been suffering a severe problem with traffic congestion. Obviously, rapidly and gradually increasing of private car ownership is considered as the main source of generating traffic congestions and negative environmental impacts. Practically, various solutions and measurements are introduced through transportation planning and traffic engineering to overcome such these problems. One of the most useful suggestions is managed lanes method. Most literature defines a managed lanes facility as one that increases freeway efficiency by packaging various operational and design action, a vary methodes is associated could be achieve these performences. Technically, the managed lanes consist of variety of applications; reversible lane, high-occupancy toll, operational strategies of exclusive lanes, truck-only toll, ramp meter bypass lane, High Occupancy Vehicle lanes (HOV) as well as Bus Rapid Transit (BRT). In this thesis, we briefly highlight critical issues associated with characteristics and configurations of each application as well as the effects of it on traffic system. Moreover, the role of some transportation information system measures such as, Transportation System Management (TSM), Intelligent Transportation System (ITS), and Transportation Demand Management (TDM) on lane management applications are discussed. For instance, ramp metering which manages the number of vehicles joining a motorway at rush hours, can be used in application and operation of HOVs technique . As mentioned previously, one of the most noticeable measurements in managed lanes is the High Occupancy Vehicle (HOV) lane technique. HOV lanes are proposed to help commuters travel faster by relieving freeway bottlenecks by assigning special lanes for high occupancy vehicles during the morning and evening rush hours and thus encouraging travel management policies. (e.g. travelling by public transport, car pool, etc.). The rules of HOV lanes vary according various traffic and transportation system indicators and are usually posted. Typically, HOV lanes are opened to vehicles handling two or more people, and sometimes access is opened to motorcycles or vehicles that use alternative fuels (hybrid or electric vehicles). In this study, evaluations of traffic performance within proposed congestion areas in Istanbul city under different HOV lane scenarios (number of vehicles that carrying 2 persons or more) are conducted. For instance, the effectiveness of HOV lanes compared to general-purpose lanes in terms of reducing delays and harmful emissions has been reported. Furthermore, the study investigates the influence of different proportions of shared vehicles, which may possibly form the base for proper policies to support the gradual shifting from drive alone to other HOVs (e.g. congestion pricing, lane tolling). Finally, several strategic improvement measurements to overcome observed traffic operation problems, are proposed under current and future conditions. The selected study area consists of two congested road segments. These sectors represent two of the most congested areas which suffer from daily traffic congestion especially during the peak periods. The first segment is Beşiktaş-Ortaköy road linking two main touristic cores of Istanbul city and has a serious congestion problem during peak hours especially evening peak. The second one is 15 Temmuz Şehitleri Bridge as one of three bridges on the Bosphorus strait that links the Asian side with the European side of the city and considers one of the most congested arterials of it. For both roads, data related to traffic volumes, average speeds, travel times, modal split, average vehicles occupancy and roads' geometric characteristics have been collected from two main sources; Istanbul Metropolitan Municipality "IBB" and Istanbul Transportation Master Plan 2011. Different measurements related to traffic and environmental effects have been obtained through modeling both roads and different proposed scenarios by using a simulation tool which is the microscopic simulation software PTV-Vissim. Overall, the thesis provides a simulation-based methodological framework to evaluate the various strategies; it involves identifying of traffic corridors that are suitable for lane use management strategies, and analyzing the strategies in terms of performance. The overall methodology comprises of four stages: (1) pre-modeling, (2) model development, (3) model calibration, and (4) model application. Pre-modeling stage comprises of tasks such as defining the scope of the project, identifying and collecting preliminary data for project implementation, and defining the study area and its scope. Model development stage comprises of task such as coding the network in VISSIM, checking for errors and debugging. Model calibration stage includes tasks like calibration and validation of the network implemented in VISSIM to ensure that the base model replicates the existing conditions on the field. Model application is the stage where number of lanes use management strategies are evaluated using the microsimulation based analysis. The results of the study showed that HOV lanes provide significant improvements compared to general-purpose lane in terms of both traffic and environmental aspects. Microsimulation analysis of high occupancy vehicle (HOV) lane strategy indicated travel speed improvement on the HOV lanes For example, for Beşiktaş-Ortaköy road segment, if 60% of drive alone travels shift to shared vehicle travels in HOV lanes, travel time reduces as high as 70%. In addition, the reduction in CO emission is approximately 50%. For 15 Temmuz Şehitleri Bridge, 67% reduction in travel times and 42% reduction in emissions are associated with 20% shifting from drive alone to shared vehicle travel modes. Such reductions in delays and fuel consumptions of HOV lanes compared with general lanes can be a motivation for attracting people who are traveling to the same (or nearby) location to share their rides.Finally, the thesis provides enough proofs that HOVs application is associated with improvements in traffic performance, environmental and economic situations.