EUROPEAN COMMISSION DIRECTORATE GENERAL ENERGY AND TRANSPORT TRIM Queue, Vejle N Denmark Evaluation report November 2009 Version 1.0 TRIM_Queue_EasyWay_Evaluation_Report_DK Updated: November 09
Document details: Date of preparation: November 2009 Abstract: Document number: Document version: 1.0 Status: EasyWay Evaluation Report Dissemination level: Public Distribution: Key audience: Associated texts: Based on translations from Trim Kø, Vejle N by Jens Toft Wendelboe January 2008 Name Organisation Tel: Email: Authors: Anders Bak Danish road directorate +4572447283 ands@vd.dk Sørensen Document Control Record: Version Main Changes: Contributions from: Date: 1.0 The majority of this report is 25/11-09 based on the evaluation described in the Danish publication Trim Kø, Vejle N by Jens Toft Wendelboe January 2008, but with added knowledge as of November 2009. TRIM_Queue_EasyWay_Evaluation_Report_DK Page ii
TABLE OF CONTENTS 1. DESCRIPTION OF THE PROBLEM... 1 1.1 Site... 1 1.2 Issues Addressed... 1 2. DESCRIPTION OF THE ITS PROJECT... 2 2.1 Objectives... 2 2.2 Systems and Technologies Applied... 2 2.3 Status of the Project... 2 3. EVALUATION... 3 3.1 Timing and Type of Evaluation... 3 3.2 Objectives for the Evaluation... 3 4. THE IMPACT OF THE PROJECT - RESULTS... 4 4.1 Technical Performance... 4 4.2 Results... 4 4.3 Overall Assessment... 5 5. EUROPEAN DIMENSION: TRANSFERABILITY OF THE RESULTS... 7 TRIM_Queue_EasyWay_Evaluation_Report_DK Page iii
1. DESCRIPTION OF THE PROBLEM 1.1 SITE The TRIM queue system was established on motorway E45/M60 north of the city Vejle during 2005-2006, and covered the stretch from exit 60 (km. 112.385) to Vejle Fjord Bridge (km. 109.670), equivalent to a distance of approx. 3 km. The system covered traffic in both directions on the motorway which in both directions at the time consisted of two lanes and a hard shoulder with a speed limit on 110 km/h. The system was discontinued in 2009. TRIM Queue Figure 1: Location of TRIM Queue on E45/M60. As can be seen from figure 1 the stretch covered by TRIM Queue turns slightly, which affects sight conditions (see also figure 2 on page 2), and furthermore the stretch is placed on a hill which drops from exit 60 (km. 112.385) to Vejle Fjord Bridge (km. 109.670) with the steepest gradient at approximately 1,5% on the 400 meters closest to the bridge. 1.2 ISSUES ADDRESSED TRIM Queue was an automatic queue warning system, which served to warn motorists of possible queue further up the road to avoid rear end collisions etc. in the widest possible way. The reasons for establishing the system was a very high frequency of rear end collisions in the area around Vejle fjord bridge and the bridge across Lillebælt. These two bridges together had a frequency of 1,7-1,8 rear end collisions pr. Km. pr. year (1999-2003). TRIM_Queue_EasyWay_Evaluation_Report_DK Page 1
2. DESCRIPTION OF THE ITS PROJECT 2.1 OBJECTIVES As mentioned TRIM Queue was an automatic queue warning system, which served to warn motorists of possible queue further up the road to avoid rear end collisions etc. in the widest possible way 2.2 SYSTEMS AND TECHNOLOGIES APPLIED The motorists were warned by the use of variable LED signs showing the symbol A20 (Warning sign Risk of Queue ) when queues were detected. Queues were detected by the use of radar detectors placed alongside the road. Figure 2: TRIM Queue warning signs and sight conditions. 2.3 STATUS OF THE PROJECT The system was established on the motorway north of Vejle during 2005-2006 and was initiated at the end of 2006. The original evaluation was carried out from September to November 2007. During the writing of this report a decision regarding a larger change of the road stretch covered (including extra lanes etc.) was taken in July 2009. As a consequence of this decision the TRIM queue system was shut down in august 2009. TRIM_Queue_EasyWay_Evaluation_Report_DK Page 2
3. EVALUATION 3.1 TIMING AND TYPE OF EVALUATION The first evaluation was carried out after approx. one year of use, and comprised two components: A technical examination regarding the technical functionality of the TRIM Queue system A user survey regarding the motorists opinion and use of TRIM Queue. The examination and the survey were carried out separately, and attention was paid not to overlap them. The results of the examination and survey have been summarized in the present Note. In continuation of the original evaluation report from January 2008 accident statistics from 2001 to 2008 has been retrieved from relevant databases and analyzed in November 2009. 3.2 OBJECTIVES FOR THE EVALUATION There were several reasons for carrying out an evaluation in 2008: What was the status of the system after one year of operation from a technical point of view? What did the users (the motorists) think about the TRIM Queue system? Which effects did the system have on the traffic? The above objectives were covered in the original Danish evaluation report from January 2008, but on the basics of accident statistics this evaluation report further address the topic What was the systems influence on traffic safety? The evaluation contributes to the Danish Road Directorate s work with gathering and documenting effects of traffic management systems, a subject in focus on both national and international level. TRIM_Queue_EasyWay_Evaluation_Report_DK Page 3
4. THE IMPACT OF THE PROJECT - RESULTS 4.1 TECHNICAL PERFORMANCE The examination regarding the technical performance of TRIM Queue can briefly be summarized as described below. Focuses were on issues that affected the functionality, and the motorists understanding of the system, which therefore were taken into account. The well-functioning parts of the system s technical functionality were therefore not mentioned /described in greater details. The technical functionality of the system was evaluated through a field study, including comparison with observations from earlier field studies. During the field study a number of incidents, where signs went out and turned back on after a short while were observed. Incidents of this sort were observed for six signs, equivalent to 33% of the signs observed. Furthermore, one incident where a sign changed to a significantly higher light intensity for a short period of time (1-2 seconds) was observed. Thus two types of malfunctions were observed during the field study. The malfunctions concerning the change in light intensity were considered less important in comparison with the malfunction where signs turned off and on unprovoked. When the signs turned off unprovoked, there was a chance that some motorists were not being warned about queues further up the road, which was contradictory to the purpose of establishing the system. 4.2 RESULTS To evaluate the systems influence on traffic safety data regarding accidents were analyzed in November 2009. The data used were accident data from 2001-2005 and 2007-2008. Data from 2006 was excluded to eliminate effects of the construction work on the site. Data was retrieved for km 109,5 112,5 (covering TRIM Queue), and reference data was retrieved for km 99-105 and 115-125. For the period before TRIM Queue was initiated (2001-2005) there was a total of 9,8 accidents per year from km 109,5-112,5 and 28,8 accidents per year for the reference stretch. For the period After TRIM Queue was initiated (2007-2008) there vas a total of 10,5 accidents per year from km 109,5-112,5 and 31,5 accidents per year for the reference stretch Looking at the absolute numbers, the improvement of traffic safety for the stretch covered by TRIM Queue would therefore appear to have worsen by 7,1%, but if one were to expect the same development in the number of accident for km 109,5-112,5 as for the reference stretch covering km 99-105 and 115-125, a total of 10,7 accidents pr. year could have been expected, which leads to a calculated improvement on 2% The same calculation has been done for different kind of accidents, the results are listed below. Total number of accidents pr. year for the area covered by TRIM Queue Accidents involving multiple vehicles travelling in the same direction pr. Year for the area covered by TRIM Queue Rear end collisions pr. Year for the area covered by TRIM Queue Injured pr. year for the area covered by TRIM Queue 2001-2005 2007-2008 improvement Cal. improvement 9,8 10,5-7,1% 2,0% 7,0 6,5 7,1% 26,6% 5,2 4,5 13,5% 49,1% 3,2 0,5 84,4% 75,9% As can be seen from the above, TRIM Queue had a very positive influence on traffic safety, even though one should have in mind that the above calculations are based on a short period of data collection after TRIM Queue was initiated (i.e. 2 years), and thus a very low number of accidents, which means that the values have a considerable degree of statistic uncertainty. TRIM_Queue_EasyWay_Evaluation_Report_DK Page 4
4.3 OVERALL ASSESSMENT On the background of the technical studies it were concluded that TRIM Queue were more or less working according to plan, even though technical malfunctions had been observed which, in respect of the systems credibility towards the motorists, should be corrected. The most important malfunctions concerned the unprovoked switch off/on of the variable signs, the less important flaw concerned signs that briefly increased light intensity. On the background of the initial study carried out in 2007 it was concluded that the system to a considerable extent fulfilled the purpose of increased traffic safety. For instance 75% of the respondents thought that the variable signs had a positive effect on traffic safety, and approx. 80% thought that the system contributed to raising the attention of the motorists. This first impression was further supported by the accident statistic analyzed in November 2009. Furthermore, the user survey showed that the motorists were quite satisfied with the system, including its functionality and location, even though there was also a widespread desire to see the system extended, so that the motorists in wider extend could be warned before they end up in a queue. In continuation of the first evaluation report from January 2008, the Danish Road Directorate repaired the technical flaws discovered through the evaluation, and supplemented TRIM Queue with variable messege signs that could be used to warn motorists about queues at an earlier stage than TRIM Queue allows. Two such signs were put into use in June 2008 at exit 58 and 59 southbound, where the problems with queues were assessed to be worst, and further two signs are currently under construction at the pull-in at Skærup and at exit 61 northbound (at km 99,515 and 116,620), despite the discontinuation of TRIM Queue. The supplementary variable message signs are thought as a kind of pre-warning about queue ahead. The variable messege signs are text signs, which can be used to display the distance to the queue ahead, and to display other kinds of traffic information. 4.3.1 User acceptance The main results of the user survey conducted among the motorists on the road stretch where the system was established are briefly summarized below. The user survey was conducted as a questionnaire survey, where questionnaires were handed out on exit 60 (northbound) and exit 61 (southbound) from 6.00 to 15.30 on Thursday Sept. 27, 2007. A total of 5,000 questionnaires were handed out, of these 1,569 were returned, equivalent to a response rate on 31. The uncertainty of the answers has been estimated to be approx. ± 2%. Generally about the respondents 72% of the respondents traveled the stretch covered by TRIM Queue every day, or almost every day, while 15% traveled the stretch one to three times per week. The rest of the respondents used the stretch less frequently. Approx. 60% of the respondents lived in the local area, and 83% of the respondents normally drove in a passenger car when they traveled the stretch. Location of the variable signs Approx. 24% of the respondents answered that the warning about queues came too late, and approx. half of the respondents would have liked an expansion of the system. The system s compliance with traffic situations When it came to TRIM Queue s compliance with the actual traffic situations, the questions referred to two different situations: One when the variable signs were turned off and one when they were turned on. The majority of the respondents (73%) found that the compliance were good when the variable signs were turned on. Regarding the situation when the signs were turned off, the number was reduced to 57%. Regarding the later situation a sum of 32% responded neutrally. The motorists use of the system 89% of the respondents answered that they expected queues or slow traffic when the variable signs were turned on. TRIM_Queue_EasyWay_Evaluation_Report_DK Page 5
92% of the respondents have seen the variable signs turned on. Out of these 92% stated that they slowed down when they saw the signs turned on. 84% of the respondents further stated that they thought other motorists slowed down when the signs were turned on. Some of the motorists who stated that they continue with the same speed stated that they do so because they were already in a queue when they passed the signs. The motorists perception of the system and its effects The motorists were asked about their perception of the influence of the variable signs on traffic safety, motorist attention and travelling speed. 73% of the respondents thought that the variable signs had a positive influence on traffic safety, while 5% stated the opposite. The remaining answered neutrally. When it comes to creating attention, 80% of the respondents answered that the variable signs had a positive influence, 3% thought that they had a negative effect, while the rest remained neutral. Approx. one third (34%) of the respondents stated that the variable signs had a positive effect on traveling speed, 16% thought that the variable signs had a negative effect on traveling speed, while the remaining 50% answered neutrally to this question. When it comes to the motorists general perception of TRIM Queue, 65% stated that the system was an advantage for their travel, 7% stated that the system was a drawback, while the remaining answered neutrally. Other matters On the back of the questionnaires space was made available so that the respondents could add remarks in free form. Approx. 40% of the respondents used this option. The remarks concerned everything from wishes regarding an expansion of TRIM Queue (36% of the 40%) to wishes regarding an expansion of the motorway etc. A part of the remarks (29% of the 40%) further concerned that the signs were not working according to plan and that they were often being repaired or out of order. A few of the respondents stated that they have experienced that the variable signs have been turned on at night, when the traffic has been very limited. 11% of the 40% further stated that the variable signs contributed to creating queues and dangerous situations since some motorists brake suddenly when the variable signs were turned on, which was contrary to the purpose of the system. However there were also motorists who used the opportunity to praise the system and the initiative behind it. Evaluation regarding the motorists perception of TRIM Queue The study showed that the motorists were quiet satisfied with the system and that they apparently did not have any problems understanding the meaning of the variable signs which were the face of TRIM Queue. There could however be doubt about the precise interpretation of the A20 symbol, but 89% answered that they expected queues or low speed when the variable signs were turned on. The study further showed that the respondents thought that the variable signs were placed in the right place, but also that there was a widespread wish to get the system expanded. On background of the study it was concluded that the system to a considerable extent fulfilled the purpose of increased traffic safety, since approx. 3/4 of the respondents answered that the variable signs had a positive effect on traffic safety. Furthermore, approx. 80% thought that the system contributed to raising the attention of the motorists. When it came to the travelling speed on the road stretch, the result of the study was less clear. All in all it was concluded that the respondents were quite satisfied with the system, even though there were room for improvement. TRIM_Queue_EasyWay_Evaluation_Report_DK Page 6
5. EUROPEAN DIMENSION: TRANSFERABILITY OF THE RESULTS The TRIM queue system didn t involve any specially developed components or functionalities and could therefore be considered a standard system, and the stretch covered by TRIM Queue was normal motorway, even though the stretch covered included small hills and wasn t completely straight which affected sight conditions (see part 1.1). On this background there is no obvious reason indicating that the results achieved with TRIM Queue couldn t be transferred to other similar road stretches with similar traffic conditions, even though it should be taken into account that driver behaviour varies from country to country and thereby affects the results. TRIM_Queue_EasyWay_Evaluation_Report_DK Page 7