Analyses of Drivers' Opinions about Railroad Grade Crossings Traffic Control Devices and Safety: Background Survey

This first survey obtained background information and opinions/experiences on participating drivers about railroad crossings. A total of 752 professional drivers representing 34 companies participated in the survey. Drivers gave an average effectiveness rating of 4.7 for crossing gates, 4.5 for flashing lights, 3.5 for clanging bell, 3.3 for train horn, 3.1 for crossbuck signs, and 3.0 for advance warning signs (5 means very high and 1 means very low). About 47% of the drivers said that railroad crossings present a significant driving hazard above normal driving conditions, but 46% said they do not. Seventy four percent of the drivers said that most railroad crossings are adequately protected/have adequate safety warning devices. However, 22% said that the crossings need more protection/more warning devices. The perception of hazards does not depend on the frequency of crossing railroad tracks or the number of times the drivers stop at the crossings. The perception of hazards does not influence the rating of the effectiveness of the warning devices. However, the perception of hazards influences the drivers’ views on the current standard of railroad grade crossing devices. The precautions drivers take when crossing the tracks are influenced by their perception of hazards and the adequacy of the current standard of warning devices. Drivers who thought crossings needed more protective warning devices rely on the train horn and advance warning signs more than other groups of drivers. Their view of the current standard of railroad warning devices also depends on the type of vehicle they drive. A higher proportion of the drivers in the group that thinks that railroad crossings need more protection drove a bus most frequently.The Illinois Department of Transportationpublished or submitted for publicationnot peer reviewe

Field Evaluation of Smart Sensor Vehicle Detectors at Railroad Grade Crossings���Volume 4: Performance in Adverse Weather Conditions

The performance of a microwave radar system for vehicle detection at a railroad grade crossing with quadrant gates was evaluated in adverse weather conditions: rain (light and torrential), snow (light and heavy), dense fog, and wind. The first part of this report compares the results of the modified system setup in adverse weather conditions with those from good weather conditions (as presented in Volume 3 of this study). Then, the results of a re-modified system setup were compared to the results for the modified system setup in good and adverse weather conditions. The re-modification was in response to increased detection errors in adverse weather conditions. With the modified setup, system performance was sensitive to the adverse weather conditions. In torrential rain, false calls increased to 24.82%–27.08% (e.g., May 28 and June 1) when there was some traffic on the crossing. However, when there was torrential rain but only one vehicle (e.g., May 31) or no traffic flow (e.g., June 10), the radar units generated 15 false calls on each of those 2 days. For all heavy snow datasets combined, missed calls by a single radar unit and by the two radar units working as a combined unit (i.e., systemwide) represented 13.51% and 11.66% of the loop calls, respectively. The most severe snow effects were found during freezing rain/ice. In dense fog, false calls increased to 11.58%, and all false calls were generated when the gates were moving or in the down position. Wind did not affect system performance, and the errors were similar to those in good weather conditions. With the re-modified setup, the frequency of errors in heavy rain and heavy snow conditions was reduced and system performance was similar to the good weather, light rain, and light snow conditions. In heavy rain, false calls in the re-modified setup were reduced to 2.6% compared with 30.5% in the modified setup. This reduction was the result of a significant decrease in the false calls generated without objects in the crossing. The re-modified setup eliminated the systemwide missed calls in heavy snow. The re-modified setup also reduced the false calls to less than 1% in good weather, light rain, and light snow conditions and practically had no missed, stuck-on, or dropped calls. Results indicate that re-modifications improved the performance of detection system.Illinois Department of Transportation, R27-095Ope

Effect of High and Low Temperatures on UPS systems for Intersection Traffic Signals

Temperature significantly affects the performance of UPS systems. Four different UPS systems were evaluated at sub-zero temperatures and hot temperatures from -25 °C to +72 °C (-13 °F to +162 °F). At high temperatures, tests were performed to ascertain the run times under normal signal operation, whether the UPS shutsdown the charging and that there is no gassing of the batteries. At sub-zero temperatures tests were performed to find the run times under normal, flashing and a combination of normal and flashing modes of operation. All the UPS systems showed longer run times as the temperature increased and drastically shorter run times as the temperature decreased. For normal operation at +72 °C condition, the percentage change in run time relative to room temperature ranged from +6% to +26%. Relative to room temperature the percentage change in run time at -25 °C condition ranged from -32% to -80% for normal operation. At the coldest temperature, the increase in duration of flashing compared to duration of normal operation ranged from 89% to 158% and the increase in combination of normal and flashing duration compared to normal operation duration ranged from 35% to 81%. It is recommended to switch to flashing or a combination of normal and flashing mode of operation in cold temperatures to increase the run time. It was also found that a UPS with a greater battery capacity may not yield greater run times under all temperature conditions.The Illinois Department of Transportationpublished or submitted for publicationnot peer reviewe

Safety Analysis and Crash Modification Factors of an Adaptive Signal Control Technology along a Corridor

The main objective of this study is to determine the safety effectiveness of the adaptive signal control technology (ASCT) SynchroGreen using an observational before and after study applying the Empirical Bayes (EB) method. Both national (HSM) and state specific (Illinois) safety performance functions (SPF) were selected and calibrated for the local conditions. A total of 14 SPFs from the HSM and 3 additional from Illinois were calibrated and crash modification factors (CMF) were developed. For multiple-vehicle fatal and injury (FI) crashes at all intersections (four-legged and three-legged combined), the CMF was 0.67, which was not statistically significant at 95 percent confidence level (it was significant at 87 percent). For four-legged-only intersections the CMF was 0.67 as well, which was not significant with 95 percent confidence (it was significant at 85 percent). The 87 and 85 percent are not confidence levels used in practice, however they clearly indicate a decreasing trend in FI crashes due to the implementation of ASCT. For PDO and total crashes, all CMF computed were very close to one indicating no crash reduction due to the implementation of ASCT. The CMF for Illinois KAB crashes (fatal, type A injury, and type B injury crashes combined) was found to be 0.68, which was not significant at 95 percent confidence level (it was significant at 71 percent indicating a decreasing trend in these types of crashes). Paired t-test results showed no reduction in sideswipe same direction, turning, and typeIDOT-R27-127Ope

Evaluation of Sensys Wireless Detection System: Year-After Evaluation and Off-Center Sensors

This is the third and final report of the evaluation of the Sensys wireless vehicle detection system at a signalized intersection and a railroad grade crossing. It presents the system performance after one year of its initial installation, and when additional off-center sensors were installed at the stop bar zones of the signalized intersection. Results from the signalized intersection showed no significant changes one year after the system was in use, except for a decrease in the frequency of false calls due to vehicles in adjacent lanes (from a range of 5.6%-7.6%, to a range of 0.8%-2.4%). At the stop bar zones, multiple calls generated by a single vehicle remained similar (between 7% and 10.2%), and no missed, stuck-on, or dropped calls were found. Also, the detection performance at the advance zones did not change. Missed vehicles ranged between 0.6% and 6.1%, most of which were traveling between lanes, and false calls were lower than 2%. At the railroad grade crossing, the performance of the Sensys system after one year did not show significant changes. Stuck-on calls due to trains were rare and occurred at a rate of about one occurrence for every 150 trains. False calls in the left-turn lane due to vehicles in the opposite direction remained high (more than 30%, caused by trucks and smaller vehicles), and missed calls were lower than 1%. The installation of sensors off-center relative to the loop detectors at the stop bar zones of the signalized intersection (close to the leading edge of the loops), resulted in lower number of multiple calls from a single vehicle (from 7%-10.2% down to 2%-3.3%). However, it did not improve on the frequency of false calls due to vehicles in the adjacent lanes.Illinois Department of Transportation ICT R27-58published or submitted for publicationnot peer reviewe

Evaluation Of Sensys Wireless Vehicle Detection System: Results From Adverse Weather Conditions

The performance of the Sensys wireless vehicle detection system was evaluated under adverse weather conditions (winter and rain) at a signalized intersection and in close proximity to the railroad tracks at a grade crossing. At the intersection stop bar zones, the overall frequency of false calls due to vehicles in the adjacent lanes ranged from 7.7% to 15.4% per lane in the winter data and between 2.6% and 6.2% in the rain data. In addition, the frequency of multiple activations due to a single vehicle (flickering false calls) ranged from 4.2% to 7.2% in the winter data and from 5% to 7.7% in the rain data. There were only seven stuck-on calls, two missed calls, and no dropped calls. At the intersection advance zones, frequency of missed vehicles traveling between the lanes ranged between 0.4% and 5.4% in the winter condition, and between 0.8% and 9.7% in the rain condition. A low percentage of vehicles traveling inside the marked lane (0%-1.2% per lane) were missed. False calls ranged on average from 1% to 4%. No stuck-on calls or dropped calls were found at the advance zones. At the railroad grade crossing, the trains generated multiple activations in the Sensys detectors as they passed the crossing. After they departed, the sensors terminated the activations except in a few cases, where the calls remained stuck-on for periods of time. In addition, false calls were the most common type of detection error, which represented 56% to 60% of the total number of calls in the left-turn lane, and 13% to 14% in the through lane. Most of the false calls in the left-turn lane were caused by vehicles traveling in the opposing direction.Illinois Department of Transportation ICT R27-58published or submitted for publicationnot peer reviewe

Evaluation of Adaptive Signal Control Technology—Volume 2: Comparison of Base Condition to the First Year After Implementation

Field evaluation of adaptive signal control technologies (ASCT) is very important in understanding the system’s contribution to safety and operational efficiency. Data were collected at six intersections along the Neil Street corridor in Champaign, Illinois, before deployment of SynchroGreen, an ASCT system. The volume, delay, and queue length data from the field for the “before” conditions (which is 2013 data) were compared to the data from the first year after implementation conditions (which is 2015 data). The system was installed in early 2015 and fined tuned by the vendor to get the “best” performance. The field volumes were compared for 83 lane groups (approaches). While traffic volume on 48% of the lane groups significantly increased, 48% did not change significantly, and only 4% significantly decreased. The field delays were compared for 83 lane groups; out of which 22% showed significant increase, 64% showed no significant change, and 14% showed significant decrease. Queue length was compared for only 63 lane groups because the remaining 20 lane groups either did not have queue data, or the queue length was insignificant (two cars or less). Out of the 63 lane groups, 32% showed significant increase, but 49% showed no significant change, and 19% showed significant decrease in queue length. ASCT performance was evaluated based on the changes in volume, delay, and queue length combined. An overall performance indicator (PI) was determined as: Imp (Improved), Unch (Unchanged), Det (Deteriorated), or Mix (mixed results). Of the 83 lane groups analyzed, 51% showed improvement, 20% remained unchanged, 28% showed deterioration, and 1% showed a mixed result. The analyses indicated that ASCT made a compromise between the minor and major street performances and, in general, the minor street improvements were correlated with the major street deterioration or unchanged performances.IDOT-R27-127Ope

Evaluation of Adaptive Signal Control Technology - Volume 3: Comparison of TBC 2017 and ASCT 2017

Data were collected at five intersections along the Neil Street corridor in Champaign, Illinois, before deployment of SynchroGreen, an adaptive signal control technology (ASCT). The volume, delay, and queue length data from the field for TBC (time based coordination) 2017 conditions were compared to the data from ASCT (adaptive signal control technology) 2017 conditions, at the 97% confidence level. The field volumes were compared for 57 lane groups (approaches). Traffic volume on 7% of the lane groups significantly increased, on 72% remained unchanged, and on only 21% significantly decreased. Stopped delays increased in 56% of the cases, remained unchanged in 40%, and decreased in 4%. Queue length increased in 35% of the cases and remained unchanged in 65%. To determine ASCT performance, the changes in volume, delay, and queue length combined were considered. An overall performance indicator (PI) was determined for each approach of each intersection at each time period. The performance indicators were Imp (Improved), Unch (Unchanged), and Det (Deteriorated), with 91% confidence. One lane group was excluded from further analysis due to insufficient volume; of the 56 lane groups analyzed, 5% showed improvement, 32% remained unchanged, and 63% (35 cases) showed deterioration. Out of 35 cases, deterioration in 20 cases could be explained by contributing factors such as frequency of unfavorable arrival types under ASCT 2017, as compared to TBC 2017; a few cases of volume increase under ASCT 2017; ASCT miscount of traffic volumes; signal timing changes under ASCT 2017; and increased proportion of vehicles stopped under ASCT 2017. However, in the 15 remaining cases, there was no reasonable explanation for the PI deteriorations when ASCT was operatingIDOT-R27-127Ope

Evaluation of Adaptive Signal Control Technology - Final Report

This report presents the results of field evaluation of an adaptive signal‐control technology (ASCT) system—SynchroGreen— deployed on the Neil Street corridor in Champaign, Illinois. The Illinois Department of Transportation (IDOT) was interested in field evaluation of an ASCT on a corridor, in terms of traffic safety and operational efficiency. SynchroGreen was selected for field implementation on six intersections along Neil Street. This report is the sixth of the ASCT study, and it provides a brief summary of the other studies and new findings regarding the ASCT performance during heavy traffic from the minor street and heavy traffic due to special events. For the “first year” evaluation, data from 2015 was used; and for the “final year” evaluation, data from 2017 was used. Unlike the outcome of the “first year” evaluation, the “final year” evaluation showed improvements on the performance indicator (PI) in only 5% of the lane groups (cases), no change in 32%, and deterioration in 63%. The system was unable to respond properly to volume increases on the minor street (Kirby Avenue), due to either peak‐hour demand or special‐ event traffic, and failed to allocate the unused green time on the major street to the minor street that had cycle failures. Multiple‐vehicle fatal and injury (FI) crashes had a crash‐modification factor (CMF) of 0.67, which was not significant at the 95% confidence level but clearly indicated a decreasing trend due to implementation of the ASCT system. Decreasing trends in the angle and rear‐end crashes, as well as Type A and Type C injuries, were observed; but they were not statistically significant. The travel times were increased in the preferred directions, which was not a desirable outcome. Several recommendations were made to vendors to provide a more desirable ASCT system.IDOT-R27-127Ope