CITROEN

Citroen Saxo VTS: The brand's compact sports car turns 30

Thirty years ago, Citroën made its mark in the world of compact sports cars with the Saxo VTS. Far from being just an urban car with a flashy emblem, it translated a clear vision: to offer enthusiasts a true 'kart for the streets' - reliable, accessible and made for fun. Three decades later, Citroën celebrates the anniversary of the small French sports car that managed to combine driving pleasure and performance within everyone's reach.

To understand the origins of the Saxo VTS, you need to go back to the AX. Launched in 1986, the AX consolidated Citroën in the compact sports car segment with the AX Sport and AX GTi versions, thanks to its precise dynamic behavior and excellent power-to-weight ratio. Introduced in February 1996, the Saxo took over the position left by the AX as the brand's entry-level model. That same year, the Saxo VTR debuted, equipped with a 1.6-liter 8-valve engine producing 90 hp. Soon after, the model destined to continue the legacy of the AX GTi arrived: the Saxo VTS, powered by the TU5J4 1.6-liter 16-valve engine, with 120 hp.

Although the general lines of the Saxo were developed by the Italian designer Donato Coco, the sports version was the responsibility of a young talent. In 1996, Gilles Vidal's first mission at Citroën was precisely to develop the visual kit for the VTS. A meticulous job, marked by widened fenders carefully integrated into the side skirts and wider bumpers. On the rear fenders, the extension goes from the wheel arch to the door cutout, sliding elegantly under the side protection trim.

The Saxo VTS knows how to hide its true nature very well. With a discreet look – marked only by the 16V emblem on the rear fenders, the chrome exhaust tip, and exclusive alloy wheels – it doesn't explicitly announce its capabilities. However, under the hood, the TU5J4 engine delivers 120 hp at 6,600 rpm, with a rev limiter at 7,300 rpm. Paired with a 5-speed manual transmission with a shorter final drive ratio and weighing only 935 kg, the VTS reaches a top speed of 205 km/h and accelerates from 0 to 100 km/h in less than 10 seconds.

But it's the chassis that truly makes the difference: the front responds with surgical precision, the power steering is well-calibrated, and the rear adopts a looser behavior, ready to slide as soon as the driver demands more from the car. On winding roads, the Saxo VTS outperforms much larger and more powerful models. Front brakes with ventilated discs complete the package of a small sports car designed for pure driving pleasure.

The Saxo VTS never rested on its laurels. At the end of 1997, a first update reorganized the sports family, and the 16-valve model once again sported the ‘16v’ emblem, previously used on the ZX. This was also the moment when Citroën expanded the VTS offering. Although the 120 hp 16v version remains the true object of desire, the sporty look and refined chassis of the VTS were now combined with more accessible engines, attracting a wider audience in search of dynamic and visually sporty performance, without necessarily prioritizing maximum performance. The VTS line then began to offer the 90 hp 1.6i engine (previously exclusive to the VTR), the 100 hp 1.6i, and even the 75 hp 1.4i.

In 1999, a significant restyling modernized the front, with almond-shaped headlights, a higher hood, and a grille with large chevrons. The VTS was updated without losing its identity. Produced until June 2003 at the Aulnay-sous-Bois factory, before giving way to the C2, the Saxo VTS ended its run after seven years of success.

As soon as it arrived on the market, the Saxo VTS proved in competitions what was already perceived in everyday use. Whether in rally, rallycross, circuit races, or even on ice, the small Citroën proved to be an extremely effective, accessible, and versatile machine.

Citroën Sport built a true competitive ecosystem around it: Saxo Cup, Saxo Challenge, Saxo Rallycross, and Saxo Glace, each with its own regulations, allowing as many drivers as possible to take their first steps in motorsport with a car developed for that purpose. Notably, these categories required the use of the production engine, demonstrating that the Saxo VTS chassis was, in itself, a true competitive weapon.

This competitive environment served as a school for an entire generation of drivers. Names like Patrick Henry, Yoann Bonato, Marc Amourette, and Pierre Llorach took their first steps in this universe before going on to much broader careers. The Saxo VTS, therefore, was not just a racing car, but also a true school of sports driving. In 2001, Sébastien Loeb and Daniel Elena won the WRC Junior world title aboard a Saxo Super 1600.

30 years later, a model that withstands the test of time...Today, the Saxo VTS has become a legitimate collector's item. Well-preserved examples are increasingly rare, and enthusiasts do not hesitate to cross France to find a model in good condition. The name Saxo VTS still appears on the entry lists of French regional rallies, proof of its extraordinary longevity in motorsport. Celebrating its 30th anniversary, Citroën pays homage to a model that, in its own way, embodied the spirit of the brand: creative, accessible, and incredibly efficient. The Saxo VTS is the story of a small car that you never thought was small.

by Autonews

AUTONEWS

The CT5-V Blackwing F1 Collector Series celebrates Cadillac’s first season in F1 with more power than ever

Cadillac is celebrating its first season in Formula 1, and this weekend marks the team’s first race on American soil at the Miami Grand Prix. To celebrate, Cadillac has launched a limited edition CT5-V Blackwing with even more power.

The CT5-V Blackwing F1 Collector Series features an upgraded supercharger developed in collaboration with GM Motorsports. This increases the power of the 6.2-liter V8 engine from 668 hp and 890 Nm to 685 hp and 910 Nm of torque.

Cadillac will offer the sports sedan exclusively with a six-speed manual transmission. Each car also comes with the Precision Package, which includes a number of upgraded suspension components, carbon-ceramic brakes and Michelin Pilot Sport Cup 2 R tires.

Each car is painted in “Midnight Stone Frost,” with Carbon Flash Metallic wheels, gloss black badging, a monochrome logo, and Harbor Gray Metallic brake calipers. The lower body features “Switchblade Silver” stripes.

The vehicle also features plenty of Formula 1 and FIA branding, including an F1 logo embossed on the lower front doors. The rear spoiler features both logos, while the FIA ​​logo adorns the sills.

Inside, the sills read “Cadillac Formula 1” and there are F1 graphics embossed on the seats. The six-speed shifter has a special F1 medallion. Under the hood, the compressor cover includes an F1 logo and a laser-engraved FIA logo.

Cadillac will begin production of the car in mid-2026, and it will be for the United States and Canada. Production is limited to just 26 examples, with a price tag of around $150,000.

Autonews

AUTONEWS

For autonomous robots, not all rules are equal

From driving cars to flying drones, as autonomous robots take on more responsibility, they also face more human-like dilemmas—including what to do when rules collide.

For a self-driving vehicle, this conundrum might pop up when a pedestrian suddenly steps off a curb and into its path. By swerving to avoid them, the car will also have to briefly veer over the road's clearly marked center line. Is this a justifiable infraction? What if it leads to a collision with an oncoming car?

Similarly, a drone might need to decide whether to fly through a narrow gap between two buildings or take the long way around to reach its destination. Neither option is perfect, but can the drone weigh the different risks that each path presents?

Tichakorn Wongpiromsarn, associate professor of computer science at Iowa State University, said these everyday scenarios reflect a growing reality: autonomous systems must make judgment calls and not just follow the rules.

"Robots are increasingly expected to operate without human intervention in situations where some rules may have to be bent," Wongpiromsarn said. "What's been missing is a principled way to justify these decisions."

This gap is what motivated Wongpiromsarn and fellow researchers Konstantin Slutsky, assistant professor of mathematics at Iowa State, and Emilio Frazzoli, professor of dynamic systems and control at ETH Zürich, to develop a new framework that helps autonomous systems make these decisions in a way that's transparent, predictable and defensible.

In a series of publications that culminated in a study published by IEEE Transactions on Robotics, Wongpiromsarn, Slutsky and Frazzoli introduce a new formal system—known as "rulebooks"—designed to help autonomous systems rank and reconcile competing goals.

Addressing common flaws...In robotics, Wongpiromsarn said there's concern around the fact that today's autonomous systems are often optimized using a single mathematical cost function that blends all goals—such as safety, legality, efficiency and passenger comfort—into one score using weighted trade-offs.

How does this work? Simply put, engineers give each of these goals a weight (or value), meaning how important that goal is relative to the other goals. A robot then calculates a total score for every possible action and picks the one with the best score.

It's an approach that works well, Wongpiromsarn said—until it doesn't.

"The problem is that this approach treats all goals as if they can be balanced against each other, even when they shouldn't be," Wongpiromsarn said.

For example, if "efficiency" is weighted too high, the robot might drive too aggressively. And while engineers can adjust the weight to make the robot behave more cautiously, that doesn't fix the underlying problem, Wongpiromsarn explained.

"In this scenario, safety is being treated as just another factor to trade off," she said. "If safety truly comes first, you can't capture that with a single weight. Safety shouldn't be balanced against other goals; it should be a hard limit that the system never crosses."

Another problem is that this trade-off is hidden inside the system. "Because it's all blended into one number, it's difficult to see why the robot chose what it did or whether the priorities were balanced correctly," Wongpiromsarn said.

Wongpiromsarn said designers may also divide system goals into "hard" and "soft" constraints, with "hard" constraints taking priority no matter the cost. But this practice, she noted, exposes another basic flaw: what should a system do when a "hard" constraint—such as preventing harm—simply can't be satisfied?

For example, in the earlier scenario during which a pedestrian suddenly steps in front of a self-driving car, the vehicle is left with two choices: attempt to brake and potentially hit the person, or swerve to avoid the person and potentially collide with an oncoming car. In this scenario, the safety constraint is impossible to fulfill.

A hard-versus-soft framework offers no guidance—it can only declare the situation unsolvable, even though the vehicle must still act, Wongpiromsarn said.

Tichakorn Wongpiromsarn, associate professor of computer science at Iowa State University, has devoted much of her career to the development of autonomous vehicles, both in academia and industry settings. Credit: Tichakorn Wongpiromsarn

New rulebooks framework uses rankings, not weights...Wongpiromsarn said the research team's new rulebooks framework avoids these issues by ranking goals instead of blending them together.

"In our framework, each rule represents a specific goal—avoiding collisions, following traffic laws and so on—and the system clearly defines which rules come first, which are tied and which can't be directly compared," she said.

Ultimately, this gives autonomous systems a principled way to compare unavoidable violations and choose the least harmful option, Wongpiromsarn said.

"This approach lets robots behave more like people," Wongpiromsarn said, noting the importance of creating frameworks that reflect "how people actually reason about what's right and wrong, safe and unsafe, and acceptable and unacceptable."

"People typically follow the most important rules first and only consider lower-priority goals once the critical ones are met or proven impossible," she said.

Slutsky said the researchers' rulebook structure also allows for gradual specification of priorities.

"This means you don't have to decide all of a robot's priorities at once," he said. "Some base priorities can be set by law, and then the company building the robot can add more priorities later—as long as they stay consistent with the base priorities."

For example, if a law said "avoid harming humans or property" is the top priority for self-driving cars, that law would be a non-negotiable "must" for manufacturers. However, that same law doesn't specify whether "stay in your lane" is more or less important than "stay away from the curb," Slutsky said, which "allows manufacturers to choose how to rank those two goals—as long as both have lower priorities than 'avoid harming humans or property.'"

"Our hope is that this approach supports compliance without over-restricting," Slutsky said. "Everyone follows the same core rules, but companies still have the freedom to innovate and design their own behavior."

Why this matters right now...Autonomous robots already face situations where it's impossible to follow every rule, and regulators recognize this.

"With the rulebooks framework, we're not computing just one 'best' action," Wongpiromsarn said. "We're identifying all actions that are optimal under a prioritized set of rules."

This difference, she said, makes it possible for engineers, regulators and even courts to ask a crucial question: Did the robot behave in line with the rules we said mattered most?

"That capability is especially important for post-incident analysis," Wongpiromsarn said. "After a crash, near-miss or regulatory review, understanding a machine's reasoning can be as important as the outcome itself."

The study also shows that rulebooks can serve as a common language for many different robot-control methods. Logical rules ("if a pedestrian is present, always yield"), optimization goals ("minimize travel time") and constraint-based approaches can all be expressed within the same framework, eliminating the need to choose between competing mathematical philosophies or technical systems.

"In our tests, we showed that our algorithms can efficiently generate plans that respect complex priority structures and even outperform standard planning methods in situations where those methods break down," Wongpiromsarn said.

The implications also go beyond robots, the researchers said, noting that as artificial intelligence systems continue to take on more decision-making in areas like transportation, coordination, health care and public safety, the need for systems that can justify their choices will only grow.

"The rulebooks concept offers a way to encode societal values, legal norms and organizational policies directly into machine decision-making," Wongpiromsarn said.

"It won't solve every ethical dilemma facing autonomous systems, but it may help ensure that when machines make hard choices, they do so according to priorities humans can understand and even hold them accountable for."

The fact that the rules for autonomous robots are not uniform is mainly due to the fact that they operate in contexts with completely different levels of risk, purposes, and physical environments.

Here are the main reasons for this variation(below):

1. Context and operating environment...The rules are shaped by the environment in which the robot operates. A robot vacuum cleaner inside a house needs few regulations, as the risk of harm is low. On the other hand, an autonomous car on a highway or a surgical robot in a hospital operates under very strict rules, as any mistake can be fatal.

2. Sectoral and ethical differences...Different sectors require distinct ethical approaches:Military: The debate on Lethal Autonomous Weapons Systems (LAWS) focuses on "who is responsible" for a life-or-death decision.Industrial: Focuses on workplace safety and the interaction between humans and heavy machinery (cobots).Social: Companionship or service robots deal with privacy and data protection laws (such as the LGPD in Brazil or GDPR in Europe). 

3. Lack of a single international treaty...There is no "World Constitution of Robotics." Each country or economic bloc (like the European Union with the AI ​​Act) is creating its own laws. This generates a mosaic of norms that vary according to the culture and political priorities of each region.

4. Complexity of civil liability...The question of "who pays the price" if something goes wrong changes everything. In some cases, the responsibility lies with the manufacturer; in others, with the programmer or even the owner. As technology evolves faster than the law, the rules are adapted as new problems arise.

5. The myth of "Asimov's laws"...Many people think of Isaac Asimov's Three Laws of Robotics (a robot may not injure a human being, etc.). While great for fiction, they are too vague for real engineering. Programming "do no harm" is extremely difficult in logical terms, as "harm" can be interpreted in a thousand different ways. 

Provided by Iowa State University 

AUTONEWS

Smart motorways were halted over safety concerns—what's the future for digital roads?

For many people, the rollout of smart technology across the UK's road network has been clouded by fears about the removal of traffic-free safety lanes. Traditionally, motorway hard shoulders offered motorists a safe haven into which they could steer stricken vehicles.

But amid growing traffic numbers, the rationale for smart motorways (part of the UK government's wider digital roads plan) was to free up these extra lanes to traffic. During a breakdown, the remote monitoring system could then quickly reinstate a temporary hard shoulder while the broken down or crashed vehicle was removed.

However, since the first official smart motorway system was introduced on the M42 near Birmingham 20 years ago, the public has repeatedly raised concerns that being stranded in a live lane rather than on a hard shoulder can be more dangerous.

In 2020, BBC Panorama reported that 38 people had been killed on smart motorways in the preceding five years. Since then, campaign groups have continued to highlight fatal collisions on smart motorway stretches where broken-down vehicles have been struck in live traffic.

In April 2023, the government's rollout of more smart motorways in England was halted by then-prime minister Rishi Sunak on the grounds of both safety and cost. However, existing smart motorways remain in operation and continue to receive safety upgrades.

The National Highways' most recent stocktake on smart motorways in England, published in December 2024, stated: "Overall, in terms of deaths or serious injuries, smart motorways remain our safest roads."

But the same year, another Panorama investigation found nearly 400 instances where safety technology had lost power on smart motorway stretches between June 2022 and February 2024.

As part of a National Highways-funded research program, I and other researchers at Cardiff University have worked with drivers and transport-sector experts to explore how people feel about the future of the UK's road network. We investigated their concerns not only around safety but also surveillance and data collection.

Sense of uncertainty...The UK's digital roads strategy entails much more than smart motorways. Even after the hiatus on building new smart motorways in England, there is still a growing ecosystem of digital and data-driven technologies embedded across the UK road network. These include roadside sensors to monitor traffic flow, cameras to detect incidents and infrastructure that communicates with control centers.

The aim is not automation for its own sake, but earlier detection of problems, faster response, smoother traffic flow and fewer serious incidents. Artificial intelligence and predictive analytics form part of this system.

Our study shows that most people are not resistant to these innovations on the roads. Many people we spoke to welcomed technologies that promise to improve safety or reduce congestion.

However, what unsettled many of them was the sense of uncertainty they felt about the rollout of these systems.

Some participants worried that data generated through digitally connected vehicles and road infrastructure could eventually "be used by insurance companies to penalize drivers."

Others raised concerns that "systems designed for traffic management might gradually expand into broader forms of surveillance."

One participant described the possibility of geolocation data revealing patterns of "my daily or weekly movement in the case of a data breach, which is dangerous."

Another wondered whether automated sensing technologies might distract drivers who feel compelled to "avoid the sensor that records what I am doing."

In general, people did not reject technological change out of hand. Rather, they want clearer safeguards around how these systems are governed, who can access the data they generate, and how accountability will be maintained as transport infrastructure becomes increasingly "intelligent." Their concerns center on questions of fairness, trust and accountability.

Technology trade-offs...Over the past 20 years, smart motorway schemes are estimated to have cost UK taxpayers billions of pounds.

The M4 smart motorway upgrade alone, between junctions 3 and 12, cost around £848 million. Recent safety reviews have committed a further £900 million to retrofit additional emergency refuge areas and improve detection systems on existing stretches.

But the costs are not only financial. There are also social and institutional costs: public confidence, legitimacy and the burden placed on road users to trust systems they did not choose and may not fully understand.

Understanding these trade-offs is important for the public. Smart road infrastructure represents a major public investment to address genuinely risky situations: broken-down vehicles, sudden congestion, poor visibility or secondary accidents caused by delayed response.

Much of this happens invisibly, which is precisely why transparency matters. When people do not understand what systems are doing, silence is easily interpreted as secrecy. Multiple parliamentary and audit reports have raised questions about whether the smart motorway rollout was too rapid, or communication to the public was inadequate—or both.

Some countries have taken a more explicit approach to public engagement around transport innovation. In Sweden, for example, the national road safety strategy, Vision Zero, was introduced as part of a broad public policy framework that placed societal consent and safety at the center of infrastructure design.

In the UK's third road investment strategy (2025-2030), smart roads will probably become more interconnected, more predictive and more automated.

Digital twins—virtual models that replicate real roads and infrastructure so planners can test scenarios before implementing them—will play a larger role in planning. Increased data sharing may allow more integrated services across multiple modes of transport. AI and analytics could increasingly support operational decisions.

But the controversy around smart motorways wasn't just about design choice. It reflects a deeper public concern: what happens when safety depends on systems people can't see or easily understand?

To answer this, the systems that run smart roads need to be open and trustworthy, safe and reliable in the eyes of those who rely on them every day.

Usage examples of the future for digital roads(below):

Predictive maintenance & digital twins: Using virtual replicas to simulate traffic, monitor structural health with sensors, and predict failures before they happen.

Autonomous vehicle integration: Road infrastructure that communicates directly with smart cars to optimize traffic flow and safety.

Intelligent traffic management: Real-time data adjustments to congestion, weather, and accidents to optimize traffic, such as dynamic lane usage.

Automated Repair Vehicles: Utilizing robotic vehicles for road maintenance, which can enhance safety during construction.

Data-Driven Safety Upgrades: Using cameras and IoT to immediately detect accidents and adjust signals, enhancing incident management.

Synonyms for Digital Roads:

-Smart roads

-Intelligent transportation systems (ITS)

-Connected infrastructure

-Intelligent roadways

-Digital twins of road networks

Key future trends and challenges(below):

Sustainability: Designing road networks that prioritize environmental efficiency.

Safety & security: While smart technology is aimed at improving safety, concerns exist regarding privacy, data breaches, and reliability of Automated Systems.

Operational shifts: Transitioning from reactive maintenance to preemptive intervention to extend asset life.

Provided by The Conversation 

CATERHAM

Caterham Seven Miami Special Edition

To mark the Formula 1 Miami Grand Prix this weekend, Caterham has prepared a limited edition of the Seven.

Called the Caterham Seven Miami Special Edition, the model is based on the track-focused Caterham Seven R and is instantly recognisable for its special enhancements. Among other things, it stands out with a special Aqua paint job with Vibrant Pink/White decals. The Miami lettering and the track shape are featured on the rear, further adding to the car’s very special nature.

According to the company, the Miami lettering is also embroidered on the headrests, and a personalised number plate is fitted to the dashboard. This reveals the very limited nature of the vehicle, as only 12 examples will be made, ten of which will be available for purchase through the company’s US dealer network.

A second plate is located under the bonnet, engraved with the names and signatures of the two workers who assembled the car at the UK factory.

Other features mentioned by the manufacturer include a grille with the "7" logo, a full windshield, side windows, carbon fiber indicators, a roll cage, 13-inch black Apollo wheels, a braking system with 254 mm discs...

The Seven Miami Special Edition is leading Caterham's new foray into the American market. Unsurprisingly, given the name, the Miami Special Edition features a livery to celebrate the Floridian city. The body is finished in a custom Aqua hue and sports a unique decal package in Vibrant Pink and white. The rear of the car reads "Miami," while the rear left fender showcases an outline of the Formula 1 circuit. The same "Miami" script appears on the headrests, and the dashboard displays a numbered plaque representing the edition's limited availability.

The special edition is based on the Seven R, which means it's restricted to track use. As with the rest of the Seven R lineup, the Miami edition sports a Ford Duratec naturally aspirated 2.0-liter engine that makes 207 horsepower and 150 pound-feet of torque. Those numbers might look wimpy—it's barely more than a Miata, after all—but the Seven R weighs just 1235 pounds, over 1200 fewer than the Mazda. That means even with a Mazda five-speed manual transmission equipped, the Caterham can zip to 60 mph in just 3.8 seconds.

Unlike the Donington special edition (limited to 10 units), this Seven Miami Special Edition is specifically for the track. It appears to be the 420R specification with a 2.0L four-cylinder Ford Duratec engine producing 210 hp, paired with a five-speed manual transmission. This translates to 0-100 km/h in 3.8 seconds, a top speed of 219 km/h, and 375 hp per ton.

Under the hood is a 2.0L four-cylinder Ford Duratec naturally aspirated engine with 157 kW/213 hp at 7600 rpm and 203 Nm of torque at 6300 rpm. The car weighs just 560 kilograms, offering a power-to-weight ratio of 375 hp per ton. Acceleration from 0 to 100 km/h takes 3.8 seconds, while the top speed is 219 km/h.

Inside, highlights include the name "Miami" stitched into the headrests, as well as a plaque on the dashboard and another in the engine bay commemorating this special edition.

Caterham is limiting production of the Miami version to just 12 units, with 10 examples allocated for U.S. customers. The automaker hasn't listed an official price for the special edition, though the standard Seven R costs $51,995.

Autonews

 

AUTONEWS

What are the reasons for traffic jams? Whether traffic flows or not depends on more than just the roads

If a city's suburban railway network is expanded, additional flats are likely to be built in an agglomeration that is better connected as a result. The opposite also holds true: If new buildings spring up like mushrooms in a suburb, this will call for an expansion of the transport infrastructure. Urban development and transport therefore have a mutual relationship.

"Our cities are becoming increasingly complex, while transport systems are under ever mounting pressure. Consequently, it is crucial to understand the relationship between mobility and cities, as this is the only way to develop and design urban centers sustainably," Yatao Zhang emphasized.

He is the first author of a study by ETH Zurich and the University of Wisconsin (U.S.), which has been published in the journal Nature Communications.

The study is based on the geoinformatics expert's doctoral thesis, which he completed in the autumn of 2025 at the Singapore-ETH Center in the Asian city state of Singapore.

A comparison of 30 cities worldwide...In this study, Zhang analyzed how urban development and traffic are mutually dependent and what cause-and-effect relationships occur. He and his colleagues compared a total of 30 major cities worldwide, including the city of Zurich.

The researchers focused on road traffic and particularly on traffic jams on congested roads. They based their investigation on traffic data from Here Technologies. The Dutch company records the congestion situation around the globe using vehicle movement data with a time resolution of five minutes. For the city of Los Angeles alone, for example, the congestion values of over 18,000 road sections were included in the study.

The scientists correlated the congestion data with a variety of characteristics of the cities analyzed. This included the structure of the road network, consisting of traffic junctions and road connections with different levels of traffic, as well as data on the shape of green spaces or districts and neighborhoods, which allows conclusions to be drawn about the flow of traffic.

The researchers also used data on the function of urban areas such as housing, shopping, sport, administration and education.

As their data source, the researchers mainly based their work on Open Street Map, a freely usable map database maintained by a community of volunteers. This resulted in a comprehensive collection of city characteristics and features for the 30 cities. The scientists correlated these with congestion data from the respective cities.

It's not just the road network that shapes and determines traffic...It is well known that urban features and traffic influence each other. Therefore, it only stands to reason that a city with a high building density or a good road infrastructure will have a lot of traffic.

Zhang and his colleagues, however, went one step further. Together, they developed a new method with which they are able to describe the mutual influence of urban features and traffic over time and even establish cause-and-effect relationships which was previously not possible.

Interesting in this context: there is a strong correlation between the expansion of the road network (urban feature structure) and traffic. The spatial arrangement of the city (urban characteristic of form), however, and the different building types (urban characteristic of function) are also determining factors for the traffic volumes.

A sprawling city tends to result in more traffic, and the accumulation of leisure activities in a neighborhood can increase weekend traffic. Mixed utilization (living and working) tends to lead to less traffic because it shortens commuting distances. ETH researcher Zhang puts it succinctly, saying, "Traffic is created by what people do, not just by the existence of roads."

Impulses for urban and transport planning...The study focused mainly on an international comparison rather than a detailed analysis of individual cities. The comparison shows major differences, for example, between Singapore and Zurich: the Asian city is characterized by demarcated residential areas that face a center with service jobs. Structural changes in residential areas have a direct impact on commuter flows.

This link between urban development and transport is much less pronounced in Zurich, as flats are spread across the entire city.

The study by Yatao Zhang's team was supervised by Martin Raubal, Professor of Geoinformation Engineering at ETH Zurich. According to Raubal, the study holds great potential in store for urban and transport planning in the medium term. "The study provides an innovative method for predicting how the change in a specific urban feature—such as the construction of a large shopping center—will impact on traffic in the medium term."

The study helps researchers to understand how transport policy measures actually work and what changes they can trigger in the urban fabric over the long term. Before the method can be used in Zurich or elsewhere for urban and transport planning, however, further detailed analyses are required.

Traffic jams are primarily caused by a mismatch between the number of vehicles on a road and that road's capacity to handle them. Experts generally categorize these causes into recurring factors (predictable daily patterns) and non-recurring incidents (random disruptions) 

1. Recurring Causes (predictable patterns)...These make up about 50% of all traffic congestion and happen on a regular, often daily, basis 

Rush hour saturation: High volumes of commuters heading to or from work at the same time overwhelm road capacity

Infrastructure bottlenecks: Permanent physical features that restrict flow, such as a multi-lane highway narrowing into fewer lanes, busy on-ramps, or bridges 

Poor urban design: Cities designed with few alternative routes or inadequate public transportation force more people into private cars 

Signal timing issues: Poorly synchronized or malfunctioning traffic lights can create unnecessary queues at intersections

2. Non-recurring causes (sudden disruptions)...These are "surprise" events that temporarily reduce a road's capacity or block it entirely

Traffic accidents: Even minor fender benders can block lanes and require emergency vehicles, causing massive ripple effects 

Roadwork and construction: Lane closures, detours, and reduced speed limits for maintenance projects naturally slow down traffic 

Inclement weather: Rain, snow, fog, or ice force drivers to slow down for safety, which reduces the overall "speed" of the road and leads to backups 

Special events: Concerts, festivals, or sporting events draw large crowds to a specific area simultaneously, overwhelming local streets 

3. Human & behavioral factors...Sometimes traffic jams occur without any physical obstruction or obvious cause 

"Phantom" Jams: A single driver braking too hard or following too closely can trigger a "wave" of braking that travels backward for miles, potentially bringing traffic to a complete standstill far from the initial event 

Rubbernecking: Drivers slowing down to look at an accident or incident on the side of the road create a secondary jam in otherwise clear lanes 

Distracted driving: Activities like texting or eating lead to inconsistent speeds and late reactions, disrupting the smooth flow of the traffic stream 

Poor driving habits: Erratic lane changes, tailgating, and aggressive merging force others to brake, which can start the "ripple effect" that leads to a jam

Provided by ETH Zurich

MERCEDES-BENZ

CLA 250+: the electric car that wants to save Mercedes in the competitive EV market

The new Mercedes-Benz CLA rights a lot of its predecessor's wrongs. Its cabin is quiet and comfortable, there's a broad set of multimedia tech and it's really quite pleasant to drive, with a well-balanced ride and confident handling. These attributes are true for both the fully electric CLA as well as the new hybrid. But one CLA variant clearly outshines the other.

The 2021 Mercedes-Benz CLA marks a revolution for the model, which now focuses on a 100% electric powertrain (with EQ technology), but still maintains hybrid options. The highlight is the CLA 250+, which becomes the entry point to the electric line of Mercedes' new MMA platform.

The 2027 CLA 220 hybrid will initially launch with front-wheel drive, but an all-wheel-drive CLA 220 4Matic will follow in late 2026. A brand-new hybrid powertrain provides motivation, combining a 1.5-liter turbocharged four-cylinder engine with a 1.3-kWh battery pack that feeds a small electric motor integrated in the eight-speed dual-clutch automatic transmission. The e-motor provides a maximum of 30 horsepower and 148 lb-ft of torque, which is really just enough to help the CLA pull away from stoplights or provide immediate boost if you step on the throttle to pass a slower-moving car on the freeway.

Mercedes says you can tool around at city speeds solely under electric power, but driving through Austria's many quaint little ski towns, the gas engine is eager to kick in. There's no dedicated EV mode to lock the CLA into electric driving; you have to use a light touch on the throttle. In practice, the CLA only wants to behave like an EV under about 5 mph. Not ideal.

What's worse, the handoff between electric power and gas assist is rough and abrupt. When the 1.5-liter turbo engine fires up, total system output increases to 208 hp and 280 lb-ft of torque. But the CLA 220 isn't exactly quick. Mercedes estimates a 0-to-60-mph time of 7.1 seconds, which is half a second slower than a Honda Civic hybrid. Efficiency estimates are still TBD, and while I do expect the CLA hybrid to return decent fuel economy, I doubt it'll be able to match the aforementioned Civic's impressive 49 mpg combined.

The eight-speed dual-clutch transmission could also stand to be refined. Across the CLA hybrid's Eco, Comfort and Sport drive settings, gear changes are jerky and ill-timed; the transmission will abruptly upshift when you're trying to make the most of the engine's power, but then hold a gear and hang out at 4,000 rpm for extended periods of time for seemingly no reason. Want to shift gears yourself? OK, just don't expect traditional steering wheel-mounted paddles. Instead, you toggle the column gear selector fore and aft, which is mega awkward.

The CLA 220's gruff hybrid engine is a turn-off, but the rest of this little sedan has lots to like. Over hundreds of miles of driving on Austrian roads, the CLA is comfortable, and the cabin is nicely insulated from wind and road noise. 

Despite its small size, the CLA has a good amount of space inside; a 6-foot-tall adult can easily fit in the back. Mercedes fits the CLA hybrid with a standard 10.3-inch gauge cluster and a 14-inch central multimedia touchscreen, but you can opt for the MBUX Superscreen, which adds a 14-inch passenger display, giving you full-dash-width digital real estate. I personally think it's a bit of tech overload — screens do not equal luxury — but it'll at least distract you from some of the less refined bits of hard plastic on the center console and door pockets.

Other nifty tech includes driver assistance features like lane-change and steering assist, plus an optional 360-degree camera system. The CLA comes standard with a large panoramic glass roof, but the ability to dim is an added extra, which is very dumb. Mercedes' Burmester 3D surround-sound stereo is another highlight. It sounds great, and the metal speaker covers look clutch.

CLA 250+ (Electric):

-Power and performance: 272 hp (268 hp) rear electric motor, capable of accelerating from 0 to 100 km/h in approximately 6.7 seconds.

-Gigantic range: Equipped with an 85 kWh battery, the model promises an impressive range of up to 780 km (WLTP). In real-world tests, the estimate is around 600 km.

-Ultra-fast charging: Thanks to the 800-volt architecture, it is possible to recover approximately 325 km of range in just 10 minutes using DC chargers up to 320 kW.

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