Erdinc Oner

Evaluation of microwave radar trailers for nonintrusive traffic measurements

A trailer using two Wavetronix microwave radar units in side-fire mode was developed to measure traffic nonintrusively, including timestamped arrival records, moving average speed (N = 16), length, and classification (0 to 20 ft, 20 to 40 ft, more than 40 ft) of each vehicle. This paper reports on an initial validation of a prototype trailer on a fourlane section of US-50 east of Athens, Ohio. Traffic on the road was independently measured with video and radar, and the results were compared with records from the trailer to verify that the trailer was measuring the traffic with reasonable accuracy. The system records the arrival of more than 95% of all vehicles, with phantom and missed counts held to less than 5% in nearly all test cases. The overall average speed based on a 90-min time period is within 3 mph of the actual overall average values, although the observed standard deviation of the trailer moving average speed readings is about two to three times that of validation data, indicating that not all...

Approximated Headway Distributions of Free-Flowing Traffic on Ohio Freeways for Work Zone Traffic Simulations

Headway or interarrival time (IAT) data of successive vehicles in free-flowing traffic ahead of work zones for each lane on six different Ohio freeways (two with two lanes in one direction, three with three lanes, and one with four lanes) for 3 days were measured and analyzed. Approximated IAT distributions were generated as a function of the traffic volume for each lane, and relationships between traffic volumes and approximate cumulative IAT distributions were established; this allowed a direct conversion from hourly traffic counts to corresponding cumulative IAT distributions. On the basis of the validation of these IAT distributions with IAT data collected in an independent study, this conversion method produces fairly accurate cumulative IAT distributions for selected hourly traffic volumes. A set of cumulative IAT distribution spreadsheets may be downloaded at webce.ent.ohiou.edu/orite/cumulativeIATdistributions.html. It was also found that the same approximated cumulative IAT distribution can be used to model and simulate free-flowing traffic at other freeway locations in Ohio. It is not known whether these universal approximated IAT distributions would apply for freeways in other states.

Traffic signal optimization with Particle Swarm Optimization for signalized roundabouts

At complex intersections, traffic congestion causes pollution and leads to accidents, high commute times and many other problems. Correct traffic signal timing can help to reduce the congestion and it can improve the traffic flow. We present a new microscopic traffic simulation-optimization model with Particle Swarm Optimization (PSO) for traffic signal timing and demonstrate the model with an application to a major roundabout with 28 traffic signal heads in Izmir, Turkey, using real data. A VISSIM (Verkehr In Städten–SIMulationsmodell) model of the Osman Kibar Roundabout, based on actual traffic flow data, is developed. A PSO model was used to search for traffic signal timings that would minimize mean travel time through the roundabout, and the microsimulation model (VISSIM) was used to evaluate the solutions from PSO. The changes in the traffic signal timings resulted in a 55.9% decrease in average delay time per vehicle passing through the roundabout, and a 9.3% increase in the number of vehicles passing through the roundabout per unit time in the best-case scenario.

Evaluation of the Benefits of Reflectorized Sign Posts to Drivers

Ozet In United States Federal Highway Administration (FHWA) provides departments of transportation (DOTs) the option of using retroreflective material on sign posts when the DOTs determine that there is a need to draw attention to the sign, especially at night. The State of Ohio Department of Transportation (ODOT) required all Stop, Yield, Do Not Enter, and Wrong Way sign posts to be reflectorized with RED reflective sheeting material and all Chevron, Stop Ahead, and One/Two Large Directional Arrow sign posts to be reflectorized with YELLOW (sign background color) reflective sheeting material as part of ODOT Comprehensive Highway Safety Plan and FHWA’ recommendations. In this study, a photometric analysis and a human factors analysis were conducted to estimate the benefits of reflectorized sign posts to driver visual perception, driver guidance and driver comprehension. The study showed that the reflectorized sign posts improve detection, recognition, and comprehension of traffic signs for drivers, especially in nighttime driving conditions.