2013 Session: 336

• Analysis of Probability of Missing an Overhead Sign due to Heavy-Vehicle-Induced Occlusion: Application to Sign Design
  Abstract: Traffic signs are an important means of communication with drivers on road. With the increase in multi-lane expressways the use of overhead signs has also increased. Like with sideway signs a driver can also miss an overhead sign due to occlusion of the sign by a leading heavy vehicle. Little or no research has been carried out to mathematically analyse conditions under which the driver of a light vehicle will not be able to read a sign due to a leading heavy vehicle. The lack of an analytical understanding of this phenomenon is reflected in the available design standards of the day. This paper analyses the conditions that lead to occlusion of overhead signs because of a leading heavy vehicle. Next, the duration for which the occlusion occurs is determined. Subsequently the results on duration of occlusion are used to evaluate whether enough time is left for the driver to read the sign. If enough time is not available then the driver is said to have “missed” the sign. The analysis indicates that there exists regions in the speed-density (u-k) space where a driver in the light vehicle will miss the sign. Assuming that the speeds of the light and heavy vehicles and the distance headway between them vary randomly, the probability of missing a sign is also obtained. This is used to determine a sign design (in terms of sign features and repetitions of the sign) which keeps the probability of missing the information on a sign below a threshold.
  Authors: Agarwal, Vivek; Chakroborty, Partha
  Authors: Agarwal, Vivek; Chakroborty, Partha
  Year: 2013
  Document Type: Paper
  Subject: Operations and Traffic Management
  Session: 336
  Paper Number: 13-0126
• Modeling Driver Behavior at Signalized Intersections in India
  Abstract: Safety at signalized intersection depends on a number of factors, among which human behaviour is the sole significant factor that is unpredictable. No serious attempts have been made to collect and analyse the driver behaviour data in Indian conditions. While a few researchers have tried to analyse the driver behaviour during the onset of yellow phase, some potentially significant factors in an heterogeneous traffic conditions have not yet been studied. No literature was available for the analysis of driver behaviour during the green and red phase. There comes the need for the present study for analysing the driver behaviour on all the three phases of the signal. This study is aimed at modelling the behaviour of drivers at few urban signalized intersections in India during yellow phase, red phase and green phase. A binomial logistic regression model was developed for the drivers’ stopping behaviour during yellow phase. The result shows that yellow-onset distance from stop line, yellow-onset speed, vehicle type and age of the driver are statistically significant factors that influence the drivers’ stopping behaviour. A multinomial logit model was developed to represent the vehicle accumulation pattern during the red phase and it was found that type of vehicle, time of arrival and the position of vehicles are all statistically significant factors. Lane changing behaviour during green phase was also modelled relating the type of vehicle, distance to intersection, the speed of the subject vehicle and the relative speed between the subject vehicle and the lead vehicle.
  Authors: Alex, Sheela; Isaac, Kuncheria P.; Varghese, Vincy
  Authors: Alex, Sheela; Isaac, Kuncheria P.; Varghese, Vincy
  Year: 2013
  Document Type: Paper
  Subject: Operations and Traffic Management
  Session: 336
  Paper Number: 13-0257
• Effects of Flashing Yellow Arrow Signal Displays on Driver Comprehension and Operations
  Abstract: In the spring of 2010, the Illinois Department of Transportation initiated an area-wide implementation of the flashing yellow arrow (FYA) as the display for the left-turn permissive interval at over 100 intersections operating with protected/permissive left-turn (PPLT) control in the Peoria, Illinois area. The authors of this paper conducted research to evaluate the effectiveness of FYAs on driver comprehension and traffic operations. A total of 363 drivers completed an online static survey that included seven left-turn scenarios which portrayed the protected and permissive indications of PPLT phasing, with the flashing modes being animated. The results of the survey indicated that drivers had a high comprehension of both the circular green (CG) and FYA permissive left-turn indications. However, the survey results provided evidence of some drivers misinterpreting the meaning of a permissive left-turn with CG display and incorrectly and unsafely interpret the meaning as “go” under some circumstances. With supplemental traffic signs present, driver understanding of the correct action to take when confronted with a FYA significantly increased, and the percentage of fail-critical, incorrect “go” responses significantly decreased. Before and after field observations including 128 hours of data collected at 16 study approaches were collected and the following variables were investigated: critical gap, left-turn red light running and yellow light running, and traffic conflicts. Overall, the findings of this study suggest that drivers in the Peoria, Illinois area had high comprehension and acceptance of the FYA message. Additionally, the FYA did not appear to have any negative impacts on traffic operations.
  Authors: Schattler, Kerrie L.; Lund, Jessica A.; Lorton, William B.; Burdett, Beau
  Authors: Schattler, Kerrie L.; Lund, Jessica A.; Lorton, William B.; Burdett, Beau
  Year: 2013
  Document Type: Paper
  Subject: Operations and Traffic Management
  Session: 336
  Paper Number: 13-0529
• Speed Reduction Impacts of Dynamic Speed Feedback Signs on Rural Two-Lane Curves
  Abstract: Horizontal curves are a particular concern since they have approximately three times the crash rate of tangent sections. Curve related crashes have a number of causes including roadway and driver factors with speed as a primary driver factor. Dynamic speed feedback signs are one traffic control device that has been successfully used to reduce vehicle speeds and, subsequently, crashes in urban applications. However, their effectiveness for rural curves has not been demonstrated. This paper describes a national demonstration project to evaluate the effectiveness of 2 different DSFS signs in reducing speed on curves at 22 total sites on rural 2 lane roadways in seven states. Data were collected before and at 1, 12 , and 24 months after installation of the DSFS. On average most sites had decreases in mean speeds with decreases up to 10.9 mph noted for both the PC and center of curve. Most sites experienced changes in 85th percentile speed of 3 or more mph at the PC with the majority of sites having a decrease of 2 mph at the center of curve. The number of vehicles traveling 5, 10, 15, or 20 mph over the posted or advisory speed limit was also compared. Large reductions in the number of vehicles traveling over the posted or advisory speed occurred for all of the after periods at the PC and center of curve indicating that the signs were effective in reducing high end speeds, as well as average and 85th percentile speeds.
  Authors: Hallmark, Shauna; Smadi, Omar G.; Hawkins, Neal R.
  Authors: Hallmark, Shauna; Smadi, Omar G.; Hawkins, Neal R.
  Year: 2013
  Document Type: Paper
  Subject: Operations and Traffic Management
  Session: 336
  Paper Number: 13-0366
• Evaluation of Recommended Variable Speed Limits for Motorway Traffic Control: Case of E4 in Stockholm, Sweden
  Abstract: Variable Speed Limits (VSL) is a form of motorway control introduced to improve the operations of freeway facilities under congested conditions. This paper evaluates the impact of VSL on the E4 motorway in Stockholm using microsimulation. The test site is heavily congested and in-cludes an integrated Motorway Control System with advisory VSL and Automatic Incident Detection (AID) logic. Experience indicates that the impacts of VSL on traffic condition and safety might be higher if the displayed VSL were mandatory. The objective of the study is to assess the impact of the level of driver compliance to VSL recommended speed, using microsimulation.
  Authors: Nissan, Albania
  Authors: Nissan, Albania
  Year: 2013
  Document Type: Paper
  Subject: Operations and Traffic Management
  Session: 336
  Paper Number: 13-0858
• Study on Relationship Between Font Height of Text Markings and Legibility Distances
  Abstract: Pavement marking symbols (such as text markings, symbol markings and arrow markings) are an important part of the traffic guide sign system. In large passenger transport hubs, pavement marking symbols can play an important role in guiding the flows of passengers. This research used field pavement text markings to analyze the relationship of the font height of text markings and the legibility distances. This research employed analysis of variance and difference of means test to identify the factors that affect the legibility distances. A regression model was developed to describe the relationship between the font height of text markings and the legibility distances. Based on this model, a variety of text marking design recommendations can be drawn, to improve the legibility and effectiveness of text pavement markings.
  Authors: Wang, Kewen
  Authors: Wang, Kewen
  Year: 2013
  Document Type: Paper
  Subject: Operations and Traffic Management
  Session: 336
  Paper Number: 13-1270
• Evaluation of Driver Perception-Reaction Times for Rainy and Wet Roadway Conditions at Onset of Yellow Indication at Signalized Intersections
  Abstract: The research presented in this paper characterizes the impact of wet pavement surface and rainy weather conditions on driver perception-reaction times (PRT) at the onset of a yellow indication on high-speed signalized intersection approaches in a controlled field environment using an in-vehicle differential Global Positioning System (GPS). A total of 384 data records were available for analysis for all drivers who stopped at the onset of the yellow indication, ranging from a minimum time-to-intersection (TTI) of 2.35 s to a maximum of 5.71 s. Statistical analyses were used to quantify the effects of the TTI, grade (uphill and downhill), gender, and age (under 40-years-old, 40 to 59-years-old, and 60 years of age or older) on driver PRTs.The study demonstrates that a driver PRT increases with a TTI increase. A longer PRT was found when vehicles travel along an upgrade section given that the driver is typically accelerating when the yellow indication is initiated. No gender differences were found in PRTs. Also, no statistically significant differences were found between different age groups. Furthermore, the study demonstrates that driver PRTs increase on wet pavement surface and rainy weather conditions when compared to clear weather conditions over the entire TTI range.
  Authors: El-Shawarby, Ihab; Abdel-Salam, Abdel-Salam Gomaa; Rakha, Hesham
  Authors: El-Shawarby, Ihab; Abdel-Salam, Abdel-Salam Gomaa; Rakha, Hesham
  Year: 2013
  Document Type: Paper
  Subject: Operations and Traffic Management
  Session: 336
  Paper Number: 13-1683
• Driving Simulator Study of Signing for Complex Interchanges
  Abstract: This paper documents a driving simulator project that identified driver lane changing behavior for six topics related to freeway guide signing at complex interchanges. Forty-two drivers from rural and urban areas of Texas used a desktop driving simulator to navigate fictional destinations by following test guide signs. Driver peformance measures included lane change proximity to interchanges and number of unnecessary lane changes. In addition, subjective measures of comfort and confidence were obtained. Almost all participants made the correct decision to exit or stay on the freeway with an option lane; however, many unnecessary lane changes were made with each of the three sign sets. For the sign set that had an arrow per lane design when signing closely spaced interchanges, all participants made correct lane change decisions. While several incorrect lane changes were made for each sign set used to evaluate signing for a Y split, the sign set that used split exit signs at all three sign bridge locations had the fewest, and was judged superior. The topics that evaluated if it is better to fill an advance single sign with supplemental wayfinding information, or to spread the information among multiple signs found that spreading information about the next exits across multiple signs on a single bridge may have unintended consequences if the sign for another exit is located to the left of the preferred lane. The topic that evaluated driver understanding of left exit signs found minimal difference between the two sign sets tested.
  Authors: Fitzpatrick, Kay; Chrysler, Susan T.; Nelson, Alicia A.; Iragavarapu, Vichika
  Authors: Fitzpatrick, Kay; Chrysler, Susan T.; Nelson, Alicia A.; Iragavarapu, Vichika
  Year: 2013
  Document Type: Paper
  Subject: Operations and Traffic Management
  Session: 336
  Paper Number: 13-1682
• Fuzzy Logic for Improved Dilemma Zone Identification: A Driving Simulator Study
  Abstract: Type-II dilemma zones are the segment of roadway approaching an intersection where drivers have difficulty deciding to stop or proceed at the onset of the circular yellow (CY) indication. Signalized intersection safety is improved when dilemma zones are correctly identified and steps are taken to reduce the likelihood that vehicles are caught in such zones. This research purports that using driving simulators as a means to collect driver response data at the onset of the CY indication is a valid methodology to augment our analysis of decisions and reactions made within the dilemma zone. The data obtained was compared against that from previous experiments documented in the literature and the evidence suggests that driving simulator data is valid for describing driver behavior under the given conditions. Fuzzy logic was proposed as a tool to model driver behavior in the dilemma zone, and three such models were developed to describe driver behavior as it relates to the speed and position of the vehicle. These models were shown to be consistent with previous research on this subject and were able to predict driver behavior with up to 90% accuracy.
  Authors: Moore, Derek; Hurwitz, David S.
  Authors: Moore, Derek; Hurwitz, David S.
  Year: 2013
  Document Type: Paper
  Subject: Operations and Traffic Management
  Session: 336
  Paper Number: 13-1835
• Impact of Lowered Residential Speed Limits in City of Edmonton, Canada
  Abstract: In 2010, the City of Edmonton reduced the posted speed limit (PSL) in six residential communities from 50 to 40 km/h. This study investigates the impact of the reduced limit on vehicle speeds using a before-after experimental design with control group adjustment.Continuous speed and traffic flow data were collected at 65 locations for a period of months including 1 month as a baseline before period and months representing the after period. Speed evaluation was performed at several levels ranging from individual speed survey locations to an over all aggregate analysis. Several performance indicators such as mean free-flow speed, speed variance, level of compliance, mean speed of speeders (drivers exceeding the PSL), and percentile speed profile were considered. The results revealed a statistically significant reduction in mean free-flow speed and speed variances for all combinations of time of day and day of week classifications. Though the compliance to the PSL was low after the limit reduction, compliance to a 15 km/h threshold above the PSL was significantly high. Moreover, the analysis showed that the effectiveness of the reduced PSL improved with the time.
  Authors: Islam, Md. Tazul; El-Basyouny, Karim; Ibrahim, Shewkar
  Authors: Islam, Md. Tazul; El-Basyouny, Karim; Ibrahim, Shewkar
  Year: 2013
  Document Type: Paper
  Subject: Operations and Traffic Management
  Session: 336
  Paper Number: 13-2157
• Left-Turn Driver Behavior During Permissive Interval of Protected-Permissive Operation Based on Signal Display
  Abstract: A study was conducted to assess the differences in operations and driver behavior when drivers were confronted with three different signal displays for the permissive interval of a protected/permissive left-turn (PPLT) phase. A comparative two-phased approach, based on field observations of driver behavior and actions recorded on video, was used to conduct this research. The Phase I research examined driver behavior at six intersection approaches in Peoria, Illinois operating with different permissive left-turn displays: circular green (CG), flashing yellow arrow (FYA) and flashing red arrow (FRA). The results of the Phase I research found that the FYA had the highest proportion of drivers’ safe and efficient actions combined as compared to the CG and FRA displays. In Phase II, a comparative analysis of four intersection approaches was conducted to determine the impacts on driver understanding of the permissive left-turn circular green display in two geographic areas: one area Peoria, Illinois that uses multiple permissive left-turn signal indications for the PPLT phase (CG, FYA, and FRA) and the second area Bloomington, Illinois that only uses the circular green indication. The results of the Phase II research found that there were no differences in driver understanding of the circular green permissive left-turn display between the two areas, based on the observed safe and efficient driver actions.
  Authors: Rietgraf, Ashley Rose; Schattler, Kerrie L.
  Authors: Rietgraf, Ashley Rose; Schattler, Kerrie L.
  Year: 2013
  Document Type: Paper
  Subject: Operations and Traffic Management
  Session: 336
  Paper Number: 13-2119
• Reliability Analysis of Traffic Signal Lights Using Fuzzy Reliability Theory
  Abstract: Over the past decade, many municipalities have begun to replace incandescent lamps in their traffic signals with light emitting diode (LED) arrays. While LED technology boasts longer lifetimes and superior performance over their counterparts, there are many limitations involved in both testing and evaluating their reliability. As such, an analysis used to evaluate the reliability of traffic signal lamps along a corridor is proposed. The purpose of the analysis was to determine the impact of LED arrays and incandescent lamps on this performance. To accomplish this task, the progression of the reliability assessment from individual lamp to the entire signal light system for a corridor is demonstrated. Furthermore, to overcome the lack of a crisp transition of a signal light system for a corridor from a success to failure state, profust or fuzzy reliability theory is employed. The results of the study indicated that the estimated reliability for a case study corridor was extremely high using the projected reliability of the signal lamps, particularly influenced by installed LED arrays. The results, coupled with field observations of partial burnouts of LED arrays and prior investigations revealing a lower than anticipated reliability of LED arrays in signal systems, suggest that manufacturer-established reliability assessments likely overestimate the true reliability of these fixtures. As such, it is recommended that fuzzy reliability theory be used to more effectively and accurately assess the reliability of individual LED arrays. Finally, as a case study of the proposed methodology, the process of modeling the reliability of signal lamps for an entire corridor is presented along with the results.
  Authors: Machemehl, Randy B.; Zhang, Zhanmin
  Authors: Machemehl, Randy B.; Zhang, Zhanmin
  Year: 2013
  Document Type: Paper
  Subject: Operations and Traffic Management
  Session: 336
  Paper Number: 13-2151
• Comprehensive Evaluation Framework of Traffic Calming Measures in Residential Area
  Abstract: Traffic calming measures are effective in enhancing traffic safety by reducing vehicle speeds. A variety of studies have evaluated the effectiveness of traffic calming measures to derive useful insights into the design and operations. Unlike existing studies focusing on either traffic performance measures or environmental impacts of the traffic calming devices, this study proposes a comprehensive evaluation framework based on microscopic traffic simulations, which enables more reliable and systematic identification of benefits for calming measures. The proposed framework evaluates the effectiveness of various traffic calming measures through three major perspectives including traffic performance, traffic safety, and environmental and public health impact. Four different traffic calming measures, two types of speed humps, speed tables, and chicanes, were applied to the proposed framework to demonstrate its usefulness and applicability. A field experiment using probe vehicles equipped with a global positioning systems (GPS) device were conducted to obtain vehicle trajectory data to be used for more realistic simulations. Also, a recently developed vehicle emissions model was used to evaluate environmental and public health impacts. Results show that speed tables and chicanes outperform others. It is expected that the outcome of this study will be a valuable decision making tool for evaluating traffic calming measures.
  Authors: Lee, Gunwoo; Joo, Shinhye; Oh, Cheol; Choi, Keechoo
  Authors: Lee, Gunwoo; Joo, Shinhye; Oh, Cheol; Choi, Keechoo
  Year: 2013
  Document Type: Paper
  Subject: Operations and Traffic Management
  Session: 336
  Paper Number: 13-3265
• Modeling Pedestrian Delay at High-Intensity Activated Crosswalk with Generalized Linear Models
  Abstract: High intensity Activated cross WalK (HAWK), as an innovative pedestrian-activated beacon, has become a hot topic and was introduced in 2009 Manual on Uniform Traffic Control Devices (MUTCD). Up till now, few studies have explored the pedestrian delay when an HWAK is installed. This paper applied the Generalized Linear Model (GLM) to model the pedestrian delay at an HAWK location. The HAWK pedestrian delay model considers the major street arrival rate, minor street arrival rate, pedestrian arrival rate, and the distance between HAWK and intersection. By using VISSIM, the operation of HAWK was simulated to provide data for HAWK pedestrian delay modeling. Four different functional forms were investigated in this paper in order to select an appropriate one that could more accurately model pedestrian delay. The results of training and validating indicated that the HWAK pedestrian delay model developed in this study is capable of effectively evaluating the pedestrian delay with a satisfactory accuracy.
  Authors: Li, Siqi; Zhang, Yunlong
  Authors: Li, Siqi; Zhang, Yunlong
  Year: 2013
  Document Type: Paper
  Subject: Operations and Traffic Management
  Session: 336
  Paper Number: 13-4095
• Comprehension and Legibility of Evaluations of International and Domestic Nonstandard Symbol Signs, Phase Two
  Abstract: Traffic signs are an important communication tool used to convey regulatory, warning, and guidance information to road users. The process for understanding user requirements for a new sign is particularly important for symbol signs, which rely on a common non-verbal interpretation by a large and diverse population of drivers. If easily understood, symbol signs can be more effective than word message signs. In this study, researchers conducted 103 surveys to determine driver comprehension and legibility for multiple sign alternatives in nine sign message categories. The sign categories were: Alternate Merge, Bike Symbol, Grade Crossing (Crossbuck), Pedestrian Crossing, Toll Collection, Truck Rollover with Advisory Speed Limit, Trucks in Roundabouts, Walk Bikes and Weave. Based on the results of the comprehension and legibility testing, the research team provided recommendations on symbols that should be included in the next edition of the Manual on Uniform Traffic Control Devices (MUTCD).
  Authors: Katz, Bryan; Dagnall, Erin; Shurbutt, Jim
  Authors: Katz, Bryan; Dagnall, Erin; Shurbutt, Jim
  Year: 2013
  Document Type: Paper
  Subject: Operations and Traffic Management
  Session: 336
  Paper Number: 13-3647
• Evaluating Impacts of Flashing Green before Amber on Drivers' Stop and Cross Decisions at Signalized Intersections in China: an empirical approach and comparative study
  Abstract: To better understand the safety effects of flashing green before amber on signalized intersections in China, this study compares drivers¡¯ stop/cross decisions at the onset of the amber phase at signalized intersections with and without flashing green, based on data collected from six approaches with sixteen exclusive through-lanes at five signalized intersections during on-peak and off-peak hours. It is found that flashing green installation serves only to encourage stopping but does not curb red light violations. In effect, flashing green adversely increases red light violations during off-peak hours due to a lengthier option zone. Meanwhile, flashing green induces aggressive drivers to pass the stop-line during amber with significantly higher speeds during off-peak hours. This effect is due to the reality of unreasonable legal regulations and acquiescence with respect to crossings by acceleration during amber in China. More specifically, the introduction of flashing green further expands the difference between drivers¡¯ acceleration/deceleration decisions, which is clearly expressed in the higher standard deviations of vehicular speeds while passing the stop-line at sites with flashing green. Moreover, flashing green alleviates drivers¡¯ underestimation of the time to the end of the amber phase, which may reduce early stops but does not sacrifice safety overall. However, flashing green apparently fails to work normally during on-peak hours. It has limited impacts on vehicular speeds, the proportions of amber-light running and red light violations, evidently due to car-following characteristics at intersections during on-peak hours.
  Authors: Dou, Xueping; Guo, Xiucheng; Gong, Xiaolin; Yang, Jie
  Authors: Dou, Xueping; Guo, Xiucheng; Gong, Xiaolin; Yang, Jie
  Year: 2013
  Document Type: Paper
  Subject: Operations and Traffic Management
  Session: 336
  Paper Number: 13-3694
• Applications of Hybrid Static-Dynamic Signs for Active Traffic Management: Worldwide State-of-the-Practice Review
  Abstract: Traditionally, static signs are used to convey messages to the road users. The need to quickly communicate up-to-date messages to the road users as part of Active Traffic Management (ATM) strategies has given rise to the increasing use of dynamic message signs (DMS). A typical DMS includes only dynamic messages. An alternative to DMS is hybrid signs, which display both static and dynamic messages on a single sign. A hybrid sign consists of a conventional retro-reflective static sign that is embedded with one or more relatively small, dynamic, usually light emitting diode (LED) message panels. Potential advantages of hybrid signs over DMS include better legibility, shorter reading time, smaller size, and lower installation, operations, and maintenance costs. This paper provides the first state-of-the-practice review on the use, design, and performance of hybrid signs. It covers hybrid sign applications in different parts of the world, including the U.S., Europe, Australia, Asia, and Africa. The application areas include variable speed limit display, speed monitoring display, parking guidance system, travel time display, managed lane operations, and graphical route information display. Multiple examples of each application, many of which were considered innovative and can potentially be adopted for use in the U.S., are given. Issues related to the applications are discussed and lessons learned are provided.
  Authors: Saha, Dibakar; Gan, Albert; Haleem, Kirolos M.; Alluri, Priyanka; Delgado, Felix Hernando
  Authors: Saha, Dibakar; Gan, Albert; Haleem, Kirolos M.; Alluri, Priyanka; Delgado, Felix Hernando
  Year: 2013
  Document Type: Paper
  Subject: Operations and Traffic Management
  Session: 336
  Paper Number: 13-4307
• Evaluation of Lighted Pavement Marking System for Lane Delineation
  Abstract: This paper presents the operational and safety evaluation and maintenance experience from the use of lighted pavement markers (LPMs) to delineate a triple left-turn movement at a signalized diamond intersection in Sugar Land, Texas. The lighted pavement markers are activated at the beginning of the green traffic signal indication for the triple left-turn movement and are intended to provide positive guidance for lane keeping, thereby reducing illegal movements and left-turn related crashes on that intersection approach. In addition, a dynamic message sign (DMS) installed 900 feet ahead of the intersection displays permitted travel movements for the three left-turn lanes and an alternate message reminding drivers to stay in their lane. The operational evaluation compared traffic volumes, lane changes, lane keeping violations, and illegal movements between the two study periods (LPM ON and LPM OFF). During the LPM ON period, the lighted pavement marker system was in place and was active, and during the LPM OFF period, the lighted pavement marker system was in place but was inactive. The DMS stayed active during both study periods. The operational evaluation showed that the lighted pavement markers appeared to reduce lane keeping violations and illegal movements. The safety evaluation compared before and after crash data for two years and shows reductions in left-turn related crashes for the study approach. While durability of pavement markers remains somewhat of a concern for the agency, periodic marker replacements have maintained the effectiveness of the lighted pavement marker system.
  Authors: Stevens, Roma Garg; Tydlacka, Jonathan; Voigt, Anthony; Worley, David C.
  Authors: Stevens, Roma Garg; Tydlacka, Jonathan; Voigt, Anthony; Worley, David C.
  Year: 2013
  Document Type: Paper
  Subject: Operations and Traffic Management
  Session: 336
  Paper Number: 13-4407
• Evaluation of Effectiveness of Portable Variable Message Signs in Reducing Speed on Rural Highway in Abu Dhabi, United Arab Emirates
  Abstract: Abu Dhabi Department of Transportation (DoT) has deployed approximately 40 Portable Variable Message Signs (PVMSs) in the year 2010 throughout the main DoT’s highway network as one of the strategies to communicate with drivers efficiently. The objective of these PVMSs is to provide drivers with adequate warnings related to severe weather conditions (e.g., fogs, dusty, rainy) and critical areas such as construction zones and school crossings. The effectiveness of PVMSs in Abu Dhabi has not been evaluated yet in any perspective. The aim of this study is to evaluate the impact of PVMSs on driver speeding behavior on rural highways. The study adopted a longitudinal approach and involved the collection of vehicular speed and classified volume data. Data collection were performed in three stages: 1) Without PVMS, 2) PVMS was installed and relaxation period was given to ensure the road users become familiar with PVMS; 3) With PVMS. Approximately half of a million vehicular data were collected at the study location. The descriptive and analytically statistical methods were used to compare speed data for the first and third stages. Results showed that there is no significant difference between mean and 85th percentile speeds for before and after installation of PVMS. PVMSs were found to be effective though statistically not significant (p-value > 0.005 at 95% confidence level) in reducing driver’s speeds on rural highway in Abu Dhabi. Further, the proportion of vehicles speeding excessively (i.e. vehicles traveling over the posted speed limit) was slightly decreased by the use of PVMS.
  Authors: Ahmed, Kamran; Al Zoubi, Khalid; Zaneldin, Essam
  Authors: Ahmed, Kamran; Al Zoubi, Khalid; Zaneldin, Essam
  Year: 2013
  Document Type: Paper
  Subject: Operations and Traffic Management
  Session: 336
  Paper Number: 13-4788
• Evaluation of Effectiveness of Speed Limit Reductions at High-Speed Intersections with Advance Warning Flasher
  Abstract: This study evaluated the effectiveness of 5 mph and 10 mph speed limit reductions in the vicinity of high-speed signalized intersections with advance warning flashers. Speed data was collected at seven intersections with different speed limit reductions in Nebraska using Wavetronix sensor and was classified and filtered to get valid data by eliminating false calls and signal control effects. Quantile regression model is used to do statistical assessment on 15th, 50th, and 85th percentile of speed distribution. At 95 percent confidence level, change of speed limit from 60 mph to 55 mph did not lead to any statistically significant reduction in 15th, 50th, or 85th percentile while the reduction from 65 mph to 55 mph led to a 4.6 mph reduction in 85th percentile speed and a 1.4 mph reduction in inter-percentile range between 15th and 85th percentiles. The mean and standard deviation of speed were estimated by seemingly unrelated regression models. The only statistically significant impact is from the speed limit reduction of 10 mph from 65 mph, which reduced the mean speed of vehicles by 3.8 mph at 95 percent confidence level.
  Authors: Wu, Zifeng; Sharma, Anuj; Wang, Shefang
  Authors: Wu, Zifeng; Sharma, Anuj; Wang, Shefang
  Year: 2013
  Document Type: Paper
  Subject: Operations and Traffic Management
  Session: 336
  Paper Number: 13-4929
• Influence of Experimental Advisory Exit Speed Limit on Freeway Exit Ramp Traffic Speeds
  Abstract: At present, advisory exit speed limit (AESL) sign is not applied widely in most China. However, it is recommended to improve the safety of exit ramp area by US Department of Transportation. The primary objective of this study is focused on the effectiveness of AESL at exit ramp area. Firstly, an evaluation model of AESL was put forward based on the field data. And then, research team collected over 400 speed observations at 7 sections of 3 different sites in Jiangsu province of China. Data collection was divided into two stages: without and with AESL. Based on the speed data, comparison analysis of speed and deceleration rate between with and without AESL was made. The results indicated that AESL had a great effect on the speed reduction at the deceleration lane. But, the speed at the ramp lane would be affected by other factors. The deceleration rate also became smoother and more stable between theoretical and physical gore. Vehicles with higher speed (over 85th percentile speed) would reduce the difference at the first half of the deceleration lane with AESL and it would cause to the reduction of ramp-related motor crashes. Thus, AESL was partly effective for the safety improvement in China. If combined with other methods, AESL would be more effective in reducing vehicles speed and enhancing traffic safety at exit ramp area. 
  Authors: Ma, Yongfeng; Sheng, Fei; Zhang, Wenbo; Zhang, Cong
  Authors: Ma, Yongfeng; Sheng, Fei; Zhang, Wenbo; Zhang, Cong
  Year: 2013
  Document Type: Paper
  Subject: Operations and Traffic Management
  Session: 336
  Paper Number: 13-4976
• Study on Relationship Between Font Height of Text Markings and Legibility Distances
  Authors: Wang, Kewen
  Authors: Wang, Kewen
  Year: 2013
  Document Type: Presentation; Poster
  Subject: Operations and Traffic Management
  Session: 336
  Paper Number: 13-1270
• Driving Simulator Study of Signing for Complex Interchanges
  Authors: Fitzpatrick, Kay
  Authors: Fitzpatrick, Kay
  Year: 2013
  Document Type: Presentation; Poster
  Subject: Operations and Traffic Management
  Session: 336
  Paper Number: 13-1682
• Evaluation of Driver Perception-Reaction Times for Rainy and Wet Roadway Conditions at Onset of Yellow Indication at Signalized Intersections
  Authors: El-Shawarby, Ihab
  Authors: El-Shawarby, Ihab
  Year: 2013
  Document Type: Presentation; Poster
  Subject: Operations and Traffic Management
  Session: 336
  Paper Number: 13-1683
• Fuzzy Logic for Improved Dilemma Zone Identification: A Driving Simulator Study
  Authors: Hurwitz, David
  Authors: Hurwitz, David
  Year: 2013
  Document Type: Presentation; Poster
  Subject: Operations and Traffic Management
  Session: 336
  Paper Number: 13-1835
• Impact of Lowered Residential Speed Limits in City of Edmonton, Canada
  Authors: El-Basyouny, Karim
  Authors: El-Basyouny, Karim
  Year: 2013
  Document Type: Presentation; Poster
  Subject: Operations and Traffic Management
  Session: 336
  Paper Number: 13-2157
• Comprehensive Evaluation Framework of Traffic Calming Measures in Residential Area
  Authors: Oh, Cheol
  Authors: Oh, Cheol
  Year: 2013
  Document Type: Presentation; Poster
  Subject: Operations and Traffic Management
  Session: 336
  Paper Number: 13-3265
• Comprehension and Legibility of Evaluations of International and Domestic Nonstandard Symbol Signs, Phase Two
  Authors: Dagnall, Erin
  Authors: Dagnall, Erin
  Year: 2013
  Document Type: Presentation; Poster
  Subject: Operations and Traffic Management
  Session: 336
  Paper Number: 13-3647
• Applications of Hybrid Static-Dynamic Signs for Active Traffic Management: Worldwide State-of-the-Practice Review
  Authors: Alluri, Priyanka
  Keywords: poster presentation; poster design; poster template
  Authors: Alluri, Priyanka
  Year: 2013
  Document Type: Presentation; Poster
  Subject: Operations and Traffic Management
  Session: 336
  Paper Number: 13-4307
• Influence of Experimental Advisory Exit Speed Limit on Freeway Exit Ramp Traffic Speeds
  Authors: Zhang, Wenbo
  Keywords: poster
  Authors: Zhang, Wenbo
  Year: 2013
  Document Type: Presentation; Poster
  Subject: Operations and Traffic Management
  Session: 336
  Paper Number: 13-4976
• Modeling Driver Behavior at Signalized Intersections in India
  Authors: Alex, Sheela
  Authors: Alex, Sheela
  Year: 2013
  Document Type: Presentation; Poster
  Subject: Operations and Traffic Management
  Session: 336
  Paper Number: 13-0257
• Speed Reduction Impacts of Dynamic Speed Feedback Signs on Rural Two-Lane Curves
  Authors: Hallmark, Shauna
  Authors: Hallmark, Shauna
  Year: 2013
  Document Type: Presentation; Poster
  Subject: Operations and Traffic Management
  Session: 336
  Paper Number: 13-0366
• Enhanced Sign Legibility and Recognition with Clearview Font: Field Study of Illinois Drivers
  Abstract:

  Illinois Interstate drivers were interviewed at four locations to gauge legibility differences between the Clearview and E-modified font in natural driving conditions. The driver interview, based on a comprehensive literature review of the Clearview font, asked drivers to identify which of six signs they recalled seeing before exiting and to evaluate the legibility of those signs. The survey also measured indicators of driver skill, familiarity, driving stress, and overall satisfaction with driving on the interstate. The qualitative and quantitative results of the driver survey, combined with the experience of Illinois and other states regarding Clearview, suggest that sign legibility alone does not vastly improve driver awareness. Age, familiarity with the road, traffic volume, time of day, and the length of driver’s license ownership were not statistically significant in explaining the number of signs drivers noticed or whether drivers found signs easy to read. The analysis suggests a range of factors mostly relating to roadway design have the greatest influence on the driving task. Some drivers complained that signs were confusing or there was not enough advance notice. At intercept locations which recently underwent major reconstruction, drivers tended to notice that signs seemed “brighter” and “bigger” than before construction, which are qualities of the background sheeting material and increased sign dimensions, respectively. These results corroborate past evidence that sheeting materials may influence legibility regardless of font, as font and sheeting material were confounded in this study.

  Authors: Frei, Charlotte; Mahmassani, Hani S.; Saberi, Meead
  Authors: Frei, Charlotte; Mahmassani, Hani S.; Saberi, Meead
  Year: 2013
  Document Type: Paper
  Subject: Operations and Traffic Management
  Session: 336
  Paper Number: 13-4565