Low-emission zones (LEZ) and zero-emission zones (ZEZ) aim to improve urban air quality by restricting the access of certain types of vehicles. Vehicles entering LEZ have to meet European standards for emissions or they incur substantial daily charges. In ZEZ, only electric vehicles are permitted.
London introduced its first LEZ in March 2008. It’s likely that other UK cities will follow their lead, affecting businesses that depend on vehicles with higher rates of emissions. To stay competitive, businesses should consider investing in newer vehicles with lower emission rates.
European emission standards are the acceptable limits for exhaust emissions created by new vehicles sold in EU member states. They’re defined in a series of EU directives, which are gradually introducing increasingly stringent standards. The numbers are as follows:
EU emission standards
Euro 1 (1993)
Euro 2 (1996)
Euro 3 (2001)
Euro 4 (2006)
Euro 5 (2009)
Euro 6 (2013)
During this period fuel consumption (which means CO2) has been reduced annually by about 1%. Each standard introduction has been met with a considerable purchase of outgoing technology. This could be because each new standard means that newly compliant engines are considerably more expensive than their predecessors. Today's engines are roughly twice as expensive to manufacture as in the early 90s.
While the majority of new commercial vehicle designs feature diesel and internal combustion engine propulsion, a variety of alternative drivelines and fuels are available. These include electric, fuel cell, bio-diesel, ethanol and natural gas technologies.
Hybrid electric vehicles (HEV) are an increasingly common alternative to today’s commercial vehicles. At the forefront of this change are bus manufacturers, thanks in part to a movement to clean up city centres.
An HEV combines a conventional internal combustion or diesel engine propulsion system with an electric system. This electric powertrain achieves better fuel economy than a conventional vehicle. Modern HEVs also make use of regenerative braking, which converts the vehicle's kinetic energy into battery replenishing electric energy. And, as they have a smaller power unit than a comparatively sized conventional vehicle – that's supplemented by an electric motor – HEVs produce fewer emissions.
HEV are classified according to how the power is supplied to the drivetrain, and the types are as follows.
In a parallel hybrids, a diesel engine works in tandem with an electric motor and battery pack. Both transmit power to drive the wheels at the same time, through a conventional transmission. Parallel hybrids are also capable of regenerative braking, and the diesel engine can act as a generator for supplemental recharging.
The drivetrain in a series hybrid is powered by an electric motor. However, a diesel engine is in place to power the electric motor or recharge its batteries. Series hybrids usually have a smaller combustion engine but a larger battery pack compared to parallel hybrids, which makes them more expensive. They’re more suited to the stop-start nature of urban vehicles, such as buses.
These HEV benefit by combining series and parallel characteristics. Where series hybrids are more efficient at lower speeds, parallel hybrids are more efficient at higher speeds. As a result, they’re more efficient overall.
Bus and coach design is increasingly driven by legislation. Principally, this has been by the Disability Discrimination Act of 1995 and its subsequent addenda designated PSVAR 2000 (Public Service Vehicle Accessibility Regulations).
PSVAR applies to all new public service vehicles introduced since 31 December 2000 with a capacity exceeding 22 passengers used to provide a local or scheduled passenger transport service. Under this legislation, all full-size single-deck buses over 7.5 tonnes must be fully accessible for disabled users from 01 January 2016, and all double-decker buses from 01 January 2017.
Buses weighing up to 7.5 tonnes and all coaches have been required to have wheelchair access since 01 January 2015. All buses weighing up to 7.5 tonnes had to be fully accessible from 01 January 2015 and coaches will need to be by 01 January 2020.
This has caused a major change in the bus and coach industry, with low-floor designs for improved accessibility. Some smaller designs achieved this by moving the door behind the front wheels. On larger buses, it’s been achieved with various independent front suspension arrangements and kneeling technology, which allows an unobstructed path into the door between the front wheel arches. Naturally, these extreme front entrance designs can’t accommodate a front mounted engine or mid-engined layout. As a result, all use a rear-engined arrangement.
Today, almost one third of full size buses are now low-floor vehicles. This figures rises over 80% in major urban areas. In London, low-floor vehicles account for 90% of the TfL fleet.
In practice, there’s no legal height limit for trailers in the UK. However, bridges spanning roads that measure over 16.5ft (5.03m) don’t have the height marked on them.
To carry the maximum permitted gross combination weight (GCW) of 44 tonnes in the UK, both tractors and semi-trailers must have three or more axles. Vehicles heavier than this aren’t allowed on UK roads, except for indivisible loads classed as abnormal or oversize. These vehicles must display a Special Types General Order (STGO ) plate on the front of the prime mover and may be required to travel an authorised route under escort. In the UK, this is mainly carried out by private companies. However, extremely large or heavy loads that require road closures must be escorted by the police.
Most UK trailers are 45 feet (13.5m) long. Depending on the position of the fifth wheel and kingpin, a coupled tractor unit and trailer will have a combined length of 50 to 55 feet (15.25 to 16.75 metres). The Construction and Use Regulations allow a maximum rigid length of 60 feet (18.2m). When combined with a shallow kingpin and fifth wheel set close to the rear of the tractor unit, this can give an overall length of around 75 feet (22.75m). Combinations of this length are very unusual, although concrete or steel beams may be carried using this combination.
Since 2009, the consequences of increasing semi-trailer length in the UK have been under consideration. This would make UK trailer lengths fit with with EU directives.
The maximum overall length in the EU and EEA member states is 18.75m, with a maximum weight of 40 tonnes – or 44 tonnes if carrying an ISO container. However, rules limit semi-trailers to 16.5m, or 18.75m if a truck is carrying a standardised 7.82m body with one additional 7.82m body as a trailer. These are referred to as drawbars and hadn’t been widely used in the UK until recently.
Several variations that could take combination lengths up to 25.25m are being considered in Europe. The drive behind these large combinations is environmental: with a 50% increase in cargo weight, fuel efficiency increases by an average of 20% and brings with it a decrease in CO2 emissions. If trailers were this size, the number of trucks on the road would reduce by a third. The plans for making trucks of this size legal in the EEA are referred to as EuroCombi.