The deployment of Long Combination Vehicles (LCVs) is underway in Sweden. LCVs are heavy vehicles exceeding the conventional length limit of 25.25 meters, as stipulated by Swedish regulations. These vehicles offer several advantages, including reduced operational costs, enhanced fuel efficiency, and lower CO2 emissions per ton-kilometer. However, despite their benefits, questions remain regarding their on-road performance. While simulation studies have provided some insights, there is a notable gap in the analysis of LCV performance using real-world traffic data.

This study evaluates the performance of LCVs using naturalistic driving data (NDD) through the application of Performance-Based Standards (PBS) measures. PBS is a regulatory framework for assessing heavy vehicles, including LCVs, based on specific metrics with quantified performance thresholds. The PBS measures used in this study are rearward amplification, low-speed swept path, high-speed transient offtracking, and high-speed steady-state offtracking. These metrics assess various aspects of vehicle stability and the space occupied during different driving scenarios. Additionally, the steering reversal rate is utilized to estimate the cognitive workload of drivers in low-speed scenarios. Two LCV configurations are used for the analysis: an A-double, which consists of a tractor-semitrailer-dolly-semitrailer or tractor-semitrailer-full trailer, and a DuoCAT, comprising a truck hauling two center-axle trailers. These vehicles are driven across different parts of Sweden for the data collection in different seasons. Four driving scenarios are examined: lane changes, maneuvering through roundabouts, turning in intersections, and negotiating tight curves.

This study fills a critical gap in the literature by assessing the real-world performance of LCVs using naturalistic driving data. The findings confirm that both A-double and DuoCAT configurations meet safety standards in a variety of driving scenarios, with each vehicle type showing distinct strengths. The results of this study can be utilised by many stakeholders, such as vehicle manufacturers, infrastructure development firms and the government for optimizing vehicle designs, maintaining and designing road networks or for making new policies.

Since December 2023, so-called High-Capacity Transport vehicles (up to 34.5 m length) are allowed on parts of the Swedish network of primarily divided roads. Investigations are ongoing under which premises longer HCT vehicles can be allowed on undivided rural roads, where cyclists and other active travellers may be present. On rural roads, overtaking manoeuvres are a frequently occurring encounter between cyclists and motorists. The fear related to dangerous overtakes is a major deterrent to rural cycling, and the aerodynamic load generated especially by large vehicles may pose a danger in that it could affect cyclist stability. To systematically investigate the effects of lateral distance, overtaking vehicle speed and truck length on cyclists stability and perception of discomfort, a controlled study was conducted in a laboratory setting. In a 700 m long tent, 23 experienced road cyclists rode on free rollers while being overtaken by a 16.5 m and a 32.5 m long truck combination at 50 and 80 km/h, with lateral distances of 1 m, 1.5 m and 2 m. Additionally, a reference overtake was run, reflecting a full lane change at reduced speed (16.5 m truck, 50 km/h, 3.5 m). Lateral distance had the largest impact on aerodynamic load and discomfort ratings, followed by speed. The length of the truck only had a minor effect. The cyclists’ lateral position on the rollers was not affected by any of the three factors, but increased slightly from before to during to after the overtaking manoeuvre, regardless of the condition. Based on these findings, a full lane change is recommended when overtaking cyclists. To which extent a speed adaptation is appropriate as compensatory measure needs to be investigated further.

Projektet HCT-City har byggt upp ny kunskap om hur urbana Högkapacitetsfordon (HCT-fordon) kan förbättra transporteffektiviteten, inklusive energi- och bränsleförbrukning samt analyserat dess effekter på infrastrukturen och den totala samhällsekonomiska kostnaden. Projektet har haft två piloter, en knuten till Varbergs tunnelprojekt och en knuten till stadsbyggnadsprojektet i Norra Djurgårdsstaden, Stockholm. Hypotesen i projektet var att det med projektets 5-axlade prototypfordon går att minska antalet fordonsrörelser med upp till 50% och CO2-utsläppen med cirka 40% utan att det får en negativ inverkan på infrastrukturen eller trafiksäkerheten. De två piloterna i Varberg och Stockholm var i karaktären olika men genererade mycket och viktiga data som förväntas möjliggöra en framtida regeländring för HCT- fordon, speciellt korta 5-axlade cityanpassade, som därmed kan möjliggöra för en implementering och en ökad samhällsnytta. De två prototyplastbilar som byggts i projektet har 5 axlar med en längd på 11 meter, och ett axelavstånd mellan första och sista axel på 7,9 meter, vilket gör att de blir lätta att manövrera och flexibla om städer har längdbegränsningar, som i Stockholm. Lastbilarna kan också kombineras med olika släp för att optimera lastkapaciteten där bärighetsklass och längdbegränsningar tillåter det.

In this study, the range estimation for a shuttle is proposed by presenting a statistical methodology to find vehicle physical parameters and applying an estimator algorithm to the remaining energy consumption calculation for the HVAC system coefficients’ determination under different ambient temperatures. The results demonstrate a high accuracy in predicting the vehicle energy consumption coefficients and allow us to use a smart charging strategy and scale up to a larger fleet of vehicles. 

To develop a range estimation algorithm the energy consumption is modeled. The model used in this work includes energy for propulsion of the shuttles, but also energy consumed for the compartment's climatization. Physical modelling is used, but data from the operation of the shuttles is used for model parametrization and validation. The used data is collected from the vehicles as well as weather data from SMHI. One challenge for model parametrization of autonomous vehicles that operate the same route is that the system is not excited in different ways. Here a method is developed to handle this by making different assumptions for the parameter values for the propulsion of the shuttles, while the parameters for the thermodynamic parameters are thereafter found. The entire model is finally evaluated using data. The model for the energy consumption is then used for range estimation of the shuttles as well as input for planning the charging of the shuttles.

Based on collected data from the vehicles in the research platform, a range estimation model is constructed regarding different weather conditions. The model achieves good representations of the collected data. The range estimation is an important input for the operation planning of the shuttles in efficient ways. The future plan is to schedule vehicle charging based on the range calculation considering battery aging, vehicle availability, and power grid impact on fleet level.

Data-driven development of friction estimators for passenger vehicles is becoming popular. They rely mainly on training data to obtain an accurate estimate of the current road conditions. However, reference or training data for natural conditions containing available friction is sparse. This limits the development of data-driven approaches for friction estimation. The current paper presents progress in a project devoted to developing a method to use standard equipment for road monitoring to acquire reference data for friction estimation, relevant to specific tyres and operating conditions. Results show how a mapping between existing test equipment readings and the real experienced coefficient of friction of a car tyre can be made. 

For more than a decade, Longer Vehicle Combinations (LVCs) have been tested in Sweden on roads and test tracks and studied in simulations. Based on the outcomes of this research, the government in Sweden has decided to open part of the road network for LVCs with a length up to 34.5 m. Necessary regulatory framework should be in place before this change can be applied. Thus, the LVCs are not expected on the roads before winter 2023-2024. This article reviews outcomes of the extensive research which has been performed on High Capacity Transport (HCT) to support introduction of LVCs in Sweden. Summary of studies on various aspects of HCT, such as regulation, safety, maneuverability, electrification, and emissions, are presented.

All-season tires have previously not been allowed to use in Sweden during winter. However, after a recent change of regulations they are now valid as winter tires if they are marked with the 3PMSF symbol, indicating that the tire has passed a standardized snow grip test. Whether the compromise between summer and winter grip makes them unsuitable for Swedish road conditions is an open question. The purpose of this study was to test the road grip of all-season tires during winter and summer conditions and compare them to regular winter and summer tires. A total of 14 all-season tires were carefully selected, together with a few studless winter tires and summer tires. Braking tests were performed on ice and snow tracks, as well as on dry and wet asphalt. It is clear from the results that the performance spread is very large among the tested all-season tires, where some manufacturers aim for grip on asphalt and others on snow. In general, the snow grip is worse than traditional winter tires of both Nordic and central European type, and especially so for the three all-season tires that were not 3PMSF marked. The ice grip of all-season tires was without exception much worse than what has been seen before in similar winter tires tests performed by VTI, and one of the all-season tires performed equally badly as one of the summer tires. Correlations between rolling resistance and grip on the different surface conditions were investigated as well.

Long Combination Vehicles (LCV) are transport efficient. However, allowing any combination of, individually legal, loaded vehicle units which when connected become LCV, can lead to traffic risks. Therefore, ways to assess LCVs are developed. The paper proposes an open tool which can assess a certain LCV for a certain load distribution. The tool could be a base for a digital service for such assessment. The assessment is done with Performance-Based Standards (PBS). PBS measures, computed through dynamic models and simulations, can be compared to numerical requirements. The vehicle parameters are selected to be as easy as possible to find values on, e.g., from available data in a vehicle unit registry. Also, the loading is defined by giving the static vertical force for each axle and the load height for each vehicle unit. A PBS based assessment method, as opposed to simply prescribing certain vehicle design parameters, would encourage novel combination vehicle designs. That would continuously drive the development towards even better transport efficiency, including energy efficiency.

A vehicle’s performance is heavily dependent on its tires’ characteristics, which is in turn affected by different tire properties, one of which is the tire tread depth. This paper investigates the effect of tread depth on the cornering performance of truck tires and presents results of a study in which a series of new and worn truck tires are measured on dry asphalt on a flat track machine. The measurement results are used for development of generic truck tire models. The effects of tread depth on the cornering coefficient, peak lateral friction and relaxation length of truck tires are analyzed, result of which is included in the models.

The deployment of High Capacity Transport (HCT) vehicles is in process in different countries. Although their performance has been assessed through simulations and test-track experiments, a question that remains unanswered is: how do these vehicles perform in real traffic? In this paper, the question is addressed for one of the transient manoeuvres, i.e., a lane change using Naturalistic Driving Data (NDD). First, an algorithm is proposed to extract lane changes from the NDD of HCT vehicles using GPS, road data and IMU signals. Following this, the performance of two A-double combinations is assessed in the extracted lane changes using measures commonly used in performance-based standards (PBS) schemes like offtracking and rearward amplification. The dependency of these measures on the factors such as the vehicle’s speed, load and lateral displacement is investigated. The assessment concludes that the vehicles satisfy the PBS requirements proposed for them and are driven safely in the extracted lane changes.