Determining a suitable position for U-turns near signal-controlled road junctions

Abstract

Previous research has shown that vehicles making U-turns at a signal-controlled urban road junction can negatively affect the performance of the junction. This paper reports on a study carried out to determine a suitable position to allow U-turns at signalised intersections in Tehran, Iran, based on their effects on network travel time. A section of the traffic network of Tehran was modelled using specialist software. To make the results more realistic, local traffic and driver behavioural parameters were calibrated and fed into the software. Various scenarios with different intervals were developed, with ten median openings before a signal-controlled junction and ten median openings after the junction. The results indicate that if the median opening for conducting U-turns is located 190 m before the junction, the network delay is lower than the other scenarios considered.

Traffic Assessment And Optimization at Signalized Intersections: A Review Study

“…25 (Mazaheri and Rahimi, 2017) Aimsun traffic software Tehran Three intersections Data were collected for 6 hours in one day, from 8 am. to 11 am and 4.30 pm to 7.30 pm.…”

“…Similar results have been reported by Dulebenets et al (2017) who stated that application of the right-turn followed by a Uturn maneuver considerably enhanced traffic performance at the studied intersection and the surrounding network. Furthermore, Mazaheri and Rahimi (2017) looked into the best and most appropriate spacing between U-turns and urban signalized intersections. Using available statistical data from Tehran's junctions, the parameters of the traffic simulator program were calibrated depending on traffic and behavioral circumstances.…”

Evaluation of Microsimulation Models for Roadway Segments with Different Functional Classifications in Northern Iran

“…Once the field data were collected, all registered vehicles were converted to the passenger car units (PCUs) using the standard PCU coefficients, which are presented in Table 3. Note that the adopted PCU coefficients have been widely used in the transportation planning of different networks in Iran [39][40][41]. Bikes and motorcycles are generally assumed to have the same PCU value (i.e., PCU = 0.3) since bikes are not very popular in Iran (i.e., installation of bike lanes is not desirable by the city authorities, as these bike lanes may occupy a substantial portion of urban streets).…”

“…As a result of the conducted analysis, it was found that the GEH values did not exceed 4.3 for the considered roadway sections, which shows a high accuracy level of the calibrated data for the car-following models that were adopted in this study. Additional field surveys were conducted in order to calibrate the physical and technical characteristics of a PCU in Iran [39][40][41]. More than 8800 vehicles of different types were analyzed in terms of the following parameters: (1) length; (2) width; (3) weight; (4) maximum speed (i.e., the maximum speed that a vehicle can achieve in a free flow traffic condition on a straight roadway section, assuming no speed limits and obstacles); and (5) maximum acceleration.…”