While the negative effects of alcohol on driving performance are undisputed, it is unclear how driver attention, eye movements and visual information sampling are affected by alcohol consumption. A simulator study with 35 participants was conducted to investigate whether and how a driver's level of attention is related to self-paced non-driving related task (NDRT)-engagement and tactical aspects of undesirable driver behaviour under increasing levels of breath alcohol concentration (BrAC) up to 1.0 ‰. Increasing BrAC levels lead to more frequent speeding, short time headways and weaving, and higher NDRT engagement. Instantaneous distraction events become more frequent, with more and longer glances to the NDRT, and a general decline in visual attention to the forward roadway. With alcohol, the compensatory behaviour that is typically seen when drivers engage in NDRTs did not appear. These findings support the theory that alcohol reduces the ability to shift attention between multiple tasks. To conclude, the independent reduction in safety margins in combination with impaired attention and an increased willingness to engage in NDRTs is likely the reason behind increased crash risk when driving under the influence of alcohol. © 2023

Under hösten 2021 fick Transportstyrelsen i uppdrag av regeringen att analysera och vid behov lämna förslag till ändrade trafikregler för att andelen trafikanter som reser med cykel ska öka. Mot bakgrund av detta har Transportstyrelsen anlitat VTI, Statens väg- och transportforskningsinstitut för att bistå i arbetet genom att beskriva kunskapsläget utifrån gällande forskning.

Syftet med uppdraget har främst varit att undersöka cyklisters utrymmesbehov i olika trafiksituationer och att ta fram underlag till rekommendationer för utformning av cykelinfrastrukturens bredder. Idag saknas regler eller gemensam byggpraxis för den fysiska utformningen av cykelfält och cykelbanor. Det är istället upp till respektive väghållare att ta fram sina egna typsektioner eller rekommendationer och kontrollera efterlevnaden.

Resultaten i denna rapport baseras på litteraturstudier gällande utformningsstandarder och forskning kring cyklisters utrymmesbehov. Rekommendationer presenteras om minstabredder på cykelbanor och cykelfält beroende på möjlighet till möten och omkörningar, inkluderat dimensionering för lastcyklar, samt trygga avstånd till sidohinder. En ansats till modellstruktur för bedömning av utrymmesbehov vid högre flöden har även tagits fram.

Cykelbanors bredd kan varieras beroende på den önskade dimensionerande trafiksituationen, det vill säga möjligheten att ett visst antal trafikanter ska kunna mötas eller köra om varandra säkert. Utifrån ett underhållsperspektiv är det dock fördelaktigt att anlägga cykelbanor med minst 2,5 meter bredd, oavsett trafiksituationen. Mindre bredd än så kan medföra lägre effektivitet för drift och underhåll med ökade livscykelkostnader som följd.

During the fall of 2021, the Swedish Transport Agency was commissioned by the Swedish Government to analyze and, if necessary, submit proposals for how changed traffic rules could lead to an increase in the proportion of road users who travel by bicycle. Against this background, the Swedish Transport Agency has engaged VTI, the Swedish Road and Transport Research Institute, to assist in the work by describing the state of knowledge based on current research in the relevant areas.

The aim of this study has been to investigate the spatial requirements of cyclists in different traffic situations and develop a basis for recommendations for designing cycling infrastructure regarding widths. Today, there are no rules or common construction practices for the physical design of cycle paths or cycle lanes in Sweden. Instead, it is up to each road authority to produce their own cross sections or recommendations and follow up on compliance.

The results in this report are based on literature studies regarding design standards and research on spatial requirements of cyclists. Recommendations are presented on minimum widths of cycle paths and cycle lanes depending on the possibility of meetings and overtaking, including consideration of cargo bikes, as well as safe distances to obstacles beside the road. An approach to model structure for assessing spatial requirements at higher flows of cyclists has also been developed.

The width of cycle paths can be varied depending on the desired dimensioning traffic situation. The dimensioning traffic situation is defined as the possibility of safe meetings or overtaking of a certain number of cyclists and pedestrians simultaneously on a cycle path or mixed-use path. From a maintenance perspective, however, it is advantageous to build bicycle infrastructure with a width of at least 2.5 meters, regardless of the traffic situation. Less width than that can result in lower efficiency for operation and maintenance with increased life cycle costs as a result.

Syftet med denna studie var att bedöma hur alkoholpåverkan interagerar med förarens uppmärksamhet och hur det påverkar lämpligheten att köra bil. Trettiofem deltagare körde i en simulator och på en testbana medan de var nyktra och under påverkan av alkohol med ökande alkoholhalt i utandningsluften (BrAC). De insamlade data inkluderade videoupptagningar av förarens huvud- och ögonrörelser, inspelningar av insidan av kupén och förarens överkropp, hjärtaktivitet och körbeteende.

Studien visade att uppmärksamhetsfördelning inte var tillräcklig för detektion av alkoholpåverkan, medan psykofysiologiska mått som fixeringstid och -hastighet samt saccad-amplituder var lämpliga kandidater för universell alkoholpåverkansdetektion. Blinkdynamiken visade också tydliga effekter av alkoholpåverkan. Placeringen av kameran bör beaktas för framtida algoritm-utveckling.

Studien visade att tre olika variabelgrupper - uppmärksamhet, utförande av extrauppgifter (NDRT) och körkvalitet – påverkades negativt efter alkoholkonsumtion. Deltagarna tenderade att titta bort från vägen längre, medan blickarna till speglarna minskade. Antalet utförda NDRT ökade med högre BrAC-nivåer, och medelblicklängden till NDRT-skärmen nästan fördubblades vid 1,0 ‰ jämfört med nykterhet. Dessutom försämrades körkvaliteten: Deltagarna körde snabbare, vinglade mer, och deras säkerhetsmarginaler gentemot andra minskade.

Kombinationen av minskad uppmärksamhet, ökat NDRT-engagemang och kompromissad körkvalitet skapar således en "farlig blandning". En diskriminant-analys genomfördes för att bedöma de kombinerade variablernas indikativa värde för BrAC-klassificering. Sammanfattningsvis fann studien att alkohol försämrar uppmärksamheten, leder till minskade säkerhetsmarginaler vid körning och mindre restriktivt engagemang i icke-körrelaterade uppgifter.

The goal of the project was to assess fitness to drive, and specifically how alcohol intoxication interacts with driver attention and drowsiness. A test track and simulator study involved 35 participants driving in a simulator and on a test track while sober and under the influence of alcohol with increasing levels of breath alcohol content. The data collected included video recordings of the driver's head and eye movements, recordings of the inside of the cabin and the driver's upper body, heart activity measurements and driving behaviour.

The study aimed to evaluate how various behavioural and psychophysiological measures froma driver monitoring system are affected by intoxication levels and if a single camera system can still robustly measure them. It was also found that attention proportion measures were not suitable for intoxication detection due to data loss, while psychophysiological measures like fixation duration and rate and saccade amplitudes were good candidates for universal intoxication detection. Blink dynamics also showed a clear effect of intoxication. It was also found that camera placement should be taken into account for future algorithm development.

The measured variables were categorized into three groups: attention, non-driving related task (NDRT) engagement, and driving quality. Most of these variables were not highly correlated. The study found that overall, all three variable groups were negatively affected after alcohol consumption. Participants tended to glance away from the forward roadway for longer periods of time, while glances to the mirrors decreased. The number of NDRTs executed increased with higher BrAC levels, and the mean glance duration to the NDRT screen almost doubled in the 1.0 ‰ condition compared to sober. Furthermore, the quality of driving deteriorated, with participants driving faster and weaving more, and their safety margins towards others were reduced.

The study suggests that the combination of decreased attention, increased NDRT engagement, and compromised driving quality creates a "dangerous cocktail" of ingredients. A discriminant analysis was conducted to assess the combined variables' indicative value for BrAC classification. The study found that alcohol impairs attention, leads to decreased safety margins in driving and less restrictive engagement in NDRT.

This study aimed to explore how travelling in different group constellations (alone, with known or with unknown people) affects children's and adults’ visual behaviour in traffic when cycling or walking. Additionally, mobile phone/earphone usage was considered, too. A follow-along study (n = 43) and an observation study (n = 898) were conducted to observe travellers in a natural setting. In the follow-along study, eye-tracking was used to investigate children's glances behaviour on their way to school and how well they manage to fulfil attentional requirements. The observational study focused on children's and adults' visual behaviour at several intersections. The main result of the study was that group membership appears to have a large influence on individuals' visual sampling strategy. In formal groups reliance on each other was found to be stronger than in informal groups. People with a natural responsibility in the group, such as parents or other adults, take a more active role in visual monitoring. Reliance on others is found to a greater extent among pedestrians than cyclists. Regarding communication devices, the use of earphones did not significantly affect glance behaviour towards relevant areas. In naturalistic situations, group constellation, age and phone/earphone usage are interlinked, which needs to be considered when studying these factors.

Cycling in rural areas is different from cycling in urban areas in that speeds of motorised vehicles are usually higher, and the interactions with other traffic almost exclusively consist of encountering oncoming traffic or being overtaken at the discretion of other traffic. Most cycling related research and politics focus on urban areas and the acquired knowledge cannot always be transferred to rural areas. The aim of this report is to provide an overview of the literature focusing on cycling in rural areas mainly with respect to safety, comfort, adequacy for cycling, and barriers and enablers for cycling. Findings and results are presented and discussed by topic, followed by a higher-level discussion focusing on issues and possibilities for increased and safe cycling. This also includes an identification of knowledge gaps. 

Presently, cycling is marginalised as a mode of transportation in the public discourse, in policies, provision of infrastructure, financing and research, and this is even more distinct for cycling in rural areas. For cycling to increase substantially in modal share, it is not enough to increase the number of cycling trips made by people who already cycle today. It is necessary that also people who do not cycle must take up cycling, which means that provisions have to be made that cater to those people’s needs. While further research is necessary here, it is known that bikeable routes that are well connected are a basic precondition, which must be coupled with effective incentives to increase cycling. This requires a remaking of the transportation policy as a whole with a systematic prioritisation of sustainable travel, which incorporates the heterogeneity of current and prospective cyclists. Special care must be taken to also consider the conditions in rural areas, to make the most of the total potential for cycling.

Att cykla på landsbygd skiljer sig från att cykla i tätorter. Motorfordonens hastigheter är vanligtvis högre och samspelet med andra trafikanter utgörs nästan uteslutande av mötande trafik eller av omkörningar på den omkörandes villkor. Samtidigt fokuserar forskning och politik främst på cykling i tätort vilket inte alltid kan överföras till förhållandena på landsbygd. Syftet med denna rapport är därför att sammanställa kunskapsläget genom en litteraturöversikt med fokus på cykling på landsbygd avseende framför allt säkerhet, komfort, lämplighet och barriärer för cykling. Resultaten presenteras och diskuteras ämnesvis och följs sedan av en mer generell diskussion med fokus på frågeställningar kring ökad och säker cykling. Detta inkluderar även identifiering av kunskapsluckor. 

I dagsläget är cykling, framför allt på landsbygd, marginaliserat i den offentliga debatten, i politiken, vid tillhandahållande av infrastruktur, samt vid finansiering och forskning. För att få till stånd en markant ökning av cykling räcker det inte med att de som cyklar börjar cykla ännu mer. Människor som i dagsläget inte cyklar måste också börja cykla vilket innebär att åtgärder måsta vidtas för att tillgodose dessa människors behov. Även om ytterligare forskning är nödvändig vet vi redan att cykelvänliga och väl sammanlänkade vägar är en grundläggande förutsättning, vilket även bör kombineras med effektiva incitament för ökad cykling. Detta kräver en övergripande omdaning av transportpolitiken där hållbart resande, systematiskt måste prioriteras med hänsyn till heterogeniteten hos dagens så väl som framtidens cyklister. Skillnaderna mellan förhållandena i staden och på landsbygden måste i detta sammanhang särskilt beaktas för att tillvarata cyklingens fulla potential.

Driver attention is often assessed via glance behaviour, typically by measuring glances away from the forward roadway or by directly measuring glances to non-driving related targets. This approach can be used to detect distracting events, but it does not check whether all situationally relevant targets are sampled. Here, we evaluate the usefulness of the MiRA-theory as basis for attention assessment. A field study was conducted with 23 participants driving an instrumented vehicle on an urban route. The participants wore a head-mounted eye tracker. Data reduction included the identification of target areas that needed to be sampled, whether they were sampled or not, and whether relevant or irrelevant other traffic was present. Additionally, a gaze-by-gaze analysis identified gaze direction, purpose, and target. As predicted, drivers sampled all required target areas that necessitated a glance away from forward. Target areas roughly in the forward direction, like zebra crossings, were probably sampled with peripheral vision, but this could not be reliably confirmed with the equipment used. The glance direction distribution was found to correspond well to the a- priori-defined requirements. A higher number of parallel requirements induced a larger share of glances with the purpose to check for traffic. Relevant traffic was monitored more than irrelevant traffic. A higher number of parallel requirements was associated with reduced spare visual capacity. Nominal glance target identification was less linked to the requirements. We therefore recommend that “traditional” glance-based attention assessment should be complemented with a purpose-based glance assessment protocol coupled with situation dependent pre-defined requirements.

To successfully get around in traffic it is often necessary to keep track of several relevant targets at the same time. This can be done by combining foveal and peripheral visual information sampling. Especially if no detailed input is needed, for example when confirming the absence of road users, it may be enough to use peripheral vision only. Using a driving simulator with an urban scenery, 35 participants passed three zebra crossings with a) no pedestrians nearby, b) pedestrians standing nearby and c) pedestrians nearby of whom one started walking towards the street. In the last case, all participants foveated the walking person, albeit around one third of the participants already released the throttle before the first glance at the pedestrian. The standing pedestrians were foveated in almost all instances, whereas the roadside nearby the zebra crossing without people nearby was not foveated by around a quarter of the participants. Taken together, the results indicate that peripheral vision may suffice to confirm the absence or presence of pedestrians. With people present, a glance towards them is initiated, likely to check for additional information. Throttle release before foveation is an indication that the walking pedestrian was detected as relevant with peripheral vision.

Idag finns uttalade mål om att andelen cykelresor ska öka och att det särskilt i tätort är angeläget att ställa om till ökat aktivt resande. Samtidigt är trafikmiljön främst byggd för biltrafik, vilket också yttrar sig i att utformningen ställer högre krav på cyklandes uppmärksamhet än på fordonsförares. En möjlighet till att åtgärda detta skulle kunna vara att flytta cykeltrafiken till mitten av körbanan i vissa tätortsmiljöer. Utöver målet att skapa ”lika villkor” mellan trafikantgrupperna ur ett uppmärksamhetsperspektiv kan detta också påverka cykelns position i trafikanthierarkin. Förslaget är ett steg i riktning mot integration av trafik istället för den idag rådande trenden mot separation. 

För att undersöka potentialen, erfarenheter och möjliga konsekvenser genomfördes dels en omvärldsanalys, dels diskussioner i sju fokusgrupper med olika intressegrupper. Konceptet ”cykelgata” finns med olika utformningar i ett antal länder. Här är lärdomen att det krävs större cykelflöden för att cykelgatan ska fungera, men det finns inga entydiga resultat på vilken utformning som är mest lämplig. Hur cykelgator uppfattas idag är också beroende av vilken typ av cyklist och cykelresa det gäller. Detta kom även fram i diskussionerna i fokusgrupperna. Man var i stort sett överens om att bilen idag har en dominerande roll, och man var teoretiskt positivt till förslaget att ha cykeltrafik i mitten av körbanan, men det identifierades ett antal praktiska samt upplevda problem och hinder. 

Sannolikt är inte en enskild åtgärd tillräcklig för att öka andelen resor som genomförs med cykel. I samverkan med andra åtgärder kan det dock bidra till att lyfta cykelns status som transportmedel. 

There are explicit goals to increase the modal share of bicycle trips and to promote a modal shift to active transport especially in urban areas. At the same time today’s transport system is mainly built for cars. One of the consequences is that in the same environment attentional demands on cyclists are higher than on drivers of motor vehicles. This could be remedied by relocating bicycle traffic to the centre of the lane in certain urban environments. In addition to creating equality between road user groups with respect to attentional demands this measure can strengthen the position of the bicycle in the hierarchy of road users. It would entail a step towards traffic integration, braking today’s trend to separate motor vehicles from other traffic. 

To analyse potential benefits and drawbacks, international solutions and experiences were investigated and seven focus group discussions with different stakeholders were conducted. The concept “bicycle boulevard” exists in several countries and comes in different shapes. For the concept to work the share of cyclists needs to be high, but no clear-cut recommendations regarding the most adequate design can be given. How bicycle boulevards are experienced also depends on the cyclist and the purpose of the trip. This emerged in the focus group discussions, too. There was a general agreement that the car is the dominant transport mode today. While it was seen as positive in principle to relocate bicycle traffic to the centre of the lane, a number of practical and psychological obstacles were identified. 

It is unlikely that a single measure will be successful in increasing the share of bicycle trips. However, in combination with other provisions, the suggested physical relocation of biycle traffic may strengthen the status of the bicycle as mode of transport.

The European Rail Traffic Management System (ERTMS) will replace national standards with the aim to promote cross-border traffic and enhance efficiency. The transition involves a shift from lineside signalling to mostly in- cabin information via a Driver Machine Interface (DMI). Previous research indicates that this may lead to a decrease in driver attention to the outside world and to a decrease in workload, leading to boredom. Using a train simulator, 41 participants drove the same track with the ERTMS system and the Swedish national standard (ATC) while wearing eye- tracking equipment. Subjective workload and boredom assessments were made after each drive. An analysis of the first set of reduced data (15 participants) showed that the formal attentional requirements like the monitoring of speed changes and signals were fulfilled in almost all cases, regardless of system. Overall, however, the data indicate that in line with previous research the drivers focus their attention more to the inside of the train when using the ERTMS system. This is corroborated by the finding that horn blowing is slightly delayed with the ERTMS system. Perceived workload was generally low, with the ERTMS system experienced to be more boring. We draw the preliminary conclusion that while formal attentional requirements are fulfilled for both systems, the ERTMS system likely has a tendency to pull the drivers’ overall attention inwards. Given that for the ERTMS system most relevant information is presented inside of the train on the DMI, this is not surprising, but needs to be addressed by the authorities.

Objective: The aim of this review is to identify how visual occlusion contributes to our understanding of attentional demand and spare visual capacity in driving and the strengths and limitations of the method.

Background: The occlusion technique was developed by John W. Senders to evaluate the attentional demand of driving. Despite its utility, it has been used infrequently in driver attention/inattention research.

Method: Visual occlusion studies in driving published between 1967 and 2020 were reviewed. The focus was on original studies in which the forward visual field was intermittently occluded while the participant was driving.

Results: Occlusion studies have shown that attentional demand varies across situations and drivers and have indicated environmental, situational, and inter-individual factors behind the variability. The occlusion technique complements eye tracking in being able to indicate the temporal requirements for and redundancy in visual information sampling. The proper selection of occlusion settings depends on the target of the research.

Conclusion: Although there are a number of occlusion studies looking at various aspects of attentional demand, we are still only beginning to understand how these demands vary, interact, and covary in naturalistic driving.

Application: The findings of this review have methodological and theoretical implications for human factors research and for the development of distraction monitoring and in-vehicle system testing. Distraction detection algorithms and testing guidelines should consider the variability in drivers’ situational and individual spare visual capacity.