| 11. |
- Hjälmdahl, Magnus, et al.
(författare)
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Speed Regulation by in-car active Accelerator pedal – effects on speed and speed distribution
- 2002
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Ingår i: IATSS Research. - 0386-1112. ; , s. 60-66
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Tidskriftsartikel (refereegranskat)abstract
- The effects on speeds and speed distribution were studied in a large scale field trial with an in car system for speed adaptation in the city of Lund, Sweden. In the trial 290 vehicles were equipped with an "active accelerator pedal" and data logger for a period of 3-11 months. Data was logged in each test vehicle during the whole trial and was analyzed for 3 one-month periods: Before activating the system, after short time use and after long time use. The results showed significant reductions in the speed level. Speeds on stretches decreased statistically significantly (p<0.05) at 60 out of 69 observed sections. The effects were largest on arterial roads, at mid-block sections, where the prevailing traffic conditions and street design allows higher speeds. The standard deviation decreased on all arterial roads, mainly due to the decrease in speed of the fastest vehicles but there is also an effect from an increase in speed of the slowest vehicles. On streets with mixed traffic no differences in speed or speed distribution could be shown. This is most likely due to the fact that speeds were already controlled by the prevailing traffic conditions and they already were so low that the system never had to interfere. Further research is needed in order to investigate possible behavioral adaptation effects when the system is active as well as inactive and how driver behavior would be influenced in a situation where a large part of the vehicle fleet equipped with an active accelerator pedal.
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| 12. |
- Hjälmdahl, Magnus, et al.
(författare)
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Validation of in-car observations, a method for driver assessment
- 2004
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Ingår i: Transportation Research. Part A: Policy & Practice. - : Elsevier BV. - 0965-8564. ; 38:2, s. 127-142
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Tidskriftsartikel (refereegranskat)abstract
- An in-car observation method with human observers in the car was studied to establish whether observers could be trained to observe safety variables and register driver's behaviour in a correct and coherent way, and whether the drivers drove in their normal driving style, despite the presence of the observers. The study further discussed the observed variables from a safety perspective. First three observers were trained in the observation method and on-road observations were carried out. Their observations were then compared with a key representing a correct observation. After practising the observation method the observers showed a high correlation with the key. To establish whether the test drivers drove in a normal way during the in-car observations, comparisons of 238 spot-speed measurements were carried out. Driver's speeds when driving their own private cars were compared with their speeds during the in-car observations. The analysis showed that the drivers drove in the same way when being observed as they did normally. Most of the variables studied in the in-car observations had a well documented relevance to traffic safety. Overall, in-car observation was shown to be a reliable and valid method to observe driver behaviour, and observed changes provide relevant data on traffic safety. (C) 2003 Elsevier Ltd. All rights reserved.
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| 13. |
- Hjälmdahl, Magnus, et al.
(författare)
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Validation of Wiener Fahrprobe – A method description.
- 2000
-
Konferensbidrag (refereegranskat)abstract
- On the decision of the Swedish government, the Swedish National Road Administration (SNRA) has started a large-scale trial with Intelligent Speed Adaptation (ISA) in urban areas. One of the four test sites is the city of Lund. At the Department of Technology and Society, Lund University, research about ISA has been carried out since 1986 and the first field study was carried out in 1993. The ongoing large scale trial is based on experience from previous research on the concept of ISA. It is likely to assume that ISA will change the speed behaviour for the test drivers, but it is also likely that there will be secondary effects related to driver behaviour. Examples of such effects are a change in communication with other road users, improved car following behaviour or, on the negative side, compensatory or automated behaviour. In order to assess the driver behaviour in the Lund trial, a method called Wiener Fahrprobe (WF) will be used. The method was originally developed by Risser and Brandstätter (1985) as an instrument to analyse driving behaviour in order to make sure whether a person is apt for driving a car or not. In the WF two observers ride along with the test-subject, one of them is doing standardised observations and the other is doing free observations (non-predictable events). In addition to the observers, an instrumented vehicle will be used to obtain continuos variables such as speed, speed-limit, distance to the vehicle in front etc. When doing observations with observers on the spot there is always a scepsis that the test-subjects will be affected and behave in a way that does not correspond with their normal driving. There are a few studies that has dealt with this issue and there are some differences in the results. Höffner, K.J. (1978) found that the behaviour of moped riders did not change when they knew that they where observed. On the other hand, Rathmayer, Beilinson, Kallio, Raitio (1999) found that subjects driving in an instrumented car with and without the presence of an experiment leader had a lowered mean speed by 1-2 km/h when the experiment leader was present. They further found that acceleration and deceleration was smoothed down and lateral acceleration was reduced. In Lund, all the test vehicles will be equipped with data-logs saving data about among others time, position and speed. These data are collected for two months before the installation of ISA and for 2*two months after the installation. These data will be compared with the data gathered during the test-drive and the differences, if any, will be analysed. The analysis will then show how and of which magnitude the drivers are affected by the observer.
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| 14. |
- Hjälmdahl, Magnus, et al.
(författare)
-
Will ISA be effective? Analysis of the active accelerator pedal’s effect on different driver groups
- 2004
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Konferensbidrag (refereegranskat)abstract
- The effects of the Active Accelerator Pedal (AAP), on speed behaviour of drivers with different backgrounds and attitudes was analysed. It was found that most of the drivers initially reduced their speed to the speed limit. However, after driving with the system for a while, speeds increased. Drivers who had a high speed without the AAP started to speed again. This finding suggests that an advisory system, such as the tested AAP, is efficient in reducing the speed of drivers who are speeding inadvertently, but it is not as efficient, however, in reducing the speed of drivers who speed deliberately.
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| 15. |
- Hjälmdahl, Magnus, et al.
(författare)
-
Workload-study of ISA-drivers - A method description.
- 2000
-
Konferensbidrag (refereegranskat)abstract
- On the decision of the Swedish government, the Swedish National Road Administration (SNRA) has started a large-scale trial with Intelligent Speed Adaptation (ISA) in urban areas. One of the four test sites is the city of Lund. At the Department of Technology and Society, Lund University, research about ISA has been carried out since 1986 and the first field study was carried out in 1993. The ongoing large scale trial is based on experience from previous research on the concept of ISA. One hypothesis regarding the effects of ISA is that the drivers will drive slower and in a more relaxed way, thus reducing the workload induced by the driving task. In order to test this hypothesis, 25 test-subjects will drive an instrumented vehicle on a predetermined route. The route consists of both urban and rural environment of varying complexity. In total, the test-drives will be carried out three times, before using ISA, after using it for a short period and finally after one year driving with ISA. During the test-drive the drivers will carry out a secondary task called “peripheral dot detection”. The task consists of responding to two lights, one on each side of the driver, by pressing one of two buttons, one for each light. The lights will be lit for 0.75 seconds and the response time, missed responses and left / right errors will be registered. In addition to the secondary task a number of other indicators of workload will be used such as lane position, speed, steering wheel rotation and NASA-TLX. Stress induced by other road-users will also be studied by studying changes in rear-view mirror glance-frequency with and without vehicles behind.
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| 16. |
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| 17. |
- Hydén, Christer, et al.
(författare)
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The effects on safety, time consumption and environment of large scale use of roundabouts in an urban area
- 2000
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Ingår i: Accident Analysis and Prevention. - 1879-2057. ; 32, s. 11-23
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Tidskriftsartikel (refereegranskat)abstract
- An experiment with small roundabouts – as speed reducing measures - was carried out in a Swedish city. The purpose of the study was to test the large scale and long term effects of the roundabouts. The results showed that the roundabouts reduced the speed considerably at the junctions and on links between roundabouts. The lateral displacement the roundabout forces the driver to has a great importance for the speed of approaching cars to a roundabout. The speed-reducing effect is large already at a 2 meter’s deflection. A larger deflection does not result in a larger effect. Conflict studies indicated an overall decrease in accident risk by 44%. Vulnerable road-users’ risk was reduced significantly, while there was no reduction for car occupants. There is a relation between the reduction of approach speed and the reduction of injury accident risk. The time consumption at a time operated signal was reduced heavily by the instalment of a roundabout at a signalised intersection. On average, emissions (CO and NOx) at roundabouts replacing non-signalised junctions increased by between 4 and 6%, while a roundabout replacing a signalised intersection led to a reduction by between 20 and 29%. The noise level was reduced at junctions that were provided with roundabout. Car drivers were less positive to the roundabouts than bicyclists. In the long term, the unchanged roundabouts worked almost as good as they did shortly after the rebuilding. The study showed that details in the design are of decisive importance for road-users’ safety. Special attention has to be paid to the situation of bicyclists. The transition between the cycle path/lane and the junction has to be designed with care - the bicyclists should be integrated with motorised traffic before they enter the roundabout. There should be only one car lane both on the approach, in the circulating area and on the exit. The size of the roundabout shall be as small as possible.
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| 18. |
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| 19. |
- Parhamifar, Ebrahim, et al.
(författare)
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PBL för Teknologer
- 2003
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Ingår i: 1:a Pedagogiska Inspirationskonferensen 2003. - 2003-3761 .- 2003-377X. ; 1
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Trots att PBL betraktas som ett kraftfullt verktyg i undervisningen, råder fortfarande viss tvekan att den skulle vara lämplig i alla utbildningar. Ett annat problem som också diskuteras är om PBL går att tillämpas på stora grupper och i så fall om den är lönsam. I tekniska utbildningar är teknologerna oftast vana vid att ha föreläsningar, övningar och laborationer. Som stöd har man ett genomarbetat kurskompendium som oftast räcker till för att lösa övningsuppgifterna. Detta betyder många gånger den korta, bekväma vägen att hitta information att lösa ett problem. I detta arbete har vi försökt att kartlägga och analysera teknologernas intresse för PBL som ett underlag för diskussioner och planering av utbildningar. Studenter från sista året i väg och vatten utbildningen som läste kurser i PBL intervjuades både individuellt och i grupp vid olika tillfällen under pågående kurs. Undersökningen genomfördes år 2001 och 2002 med 26 respektive 16 teknologer. Resultaten från både tillfällen visar att teknologerna var i allmänt positiva till PBL. En förändring i inställningen till PBL noterades hos intervjuade personer under kursen gång. Problemet som nästan alla var eniga om var att man läste samtidigt andra kurser med den traditionella undervisningsformen och därför tyckte man att PBL tog mer tid. Man tyckte också att PBL inte passar till alla kurser. Metodiken gör sig bättre i ”läskurser” än i t ex ”matematikkurser”. Det är dock en fördel om hela utbildningen ges med PBL eftersom det blir mindre rörigt för studenterna då.
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| 20. |
- Varhelyi, Andras, et al.
(författare)
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A large-scale trial with Intelligent Speed Adaptation in Lund, Sweden.
- 2000
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Ingår i: [Host publication title missing].
-
Konferensbidrag (refereegranskat)abstract
- On the decision of the Swedish government, the Swedish National Road Administration (SNRA) has started a large-scale trial with Intelligent Speed Adaptation (ISA) in urban areas. One of the four test sites is the city of Lund. At the Department of Technology and Society, Lund University, research about ISA has been carried out since 1986 and the first field study was carried out in 1993. The ongoing large scale trial is based on experience from previous research on the concept of ISA. The major findings from these trials where that speeds on stretches decreased, car-following behaviour improved and the acceptance of the system increased after using it. In the ongoing trial, technology has made it possible to log all driving data of all equipped vehicles with regard to time, position, rpm and speed, both before and after installation of the speed-limiter. There will also be a focus on driver behaviour and workload. This will be evaluated by using an instrumented vehicle. Also system effects, such as speeds, interactions with other road-users, driving against red, emissions will be investigated.
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