Heavy vehicle selection guide

1. Introduction
2. Operating environment and vehicle layout
3. Vehicle performance
4. Health and safety
5. Maintenance
6. Appearance
7. Checklist
8. Axle weights calculator

1.Introduction

This guide is designed to help you, as a heavy vehicle purchaser, choose the right vehicle to improve your business's efficiency, safety and – ultimately – profitability.

The purchase or lease of a new vehicle can add real value to your operation. For example, you'll probably want to boost the vehicle's payload capacity and/or reduce maintenance costs. Choosing a more fuel-efficient vehicle may also be a priority. The right vehicle can help enhance your business image with your customers and you may also want to consider driver preferences. And, of course, there are the basics – improved safety and increased reliability.

Initial purchase price vs lifecycle cost

When selecting a new or replacement vehicle, it is advisable to consider the lifecycle cost of the vehicle, not just the initial purchase price. What's really important is to minimise all of the direct and indirect expenses throughout the life of the vehicle. Choosing the cheapest vehicle on the market today may prove to be false economy tomorrow.

The graph below shows the cost of operating a vehicle over its life. The point marked 'Replacement' indicates the stage at which the cost of operating the vehicle is greater than replacing it. This point varies according to the resale value of the vehicle purchased. The lower part of the graph shows different factors that contribute to the vehicle's value over time.

Direct and indirect costs

Both the direct and indirect costs associated with operating a heavy vehicle need to be considered when making your selection.

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Suggested process for selection

There are five broad areas that should be considered when purchasing or leasing a vehicle. These are shown below.

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2.Operating environment and vehicle layout

The first step is to determine what the vehicle will be used for, the conditions it will regularly be operating under and any other operational or legal constraints. This information will provide the basic requirements for the vehicle including the type of loads that it will be able to carry, how much deck space is required, the type of body to be fitted and how loads will be secured. Don't forget to consider requirements such as road user charges (RUC), static rollover threshold (SRT) and the Land Transport Vehicle Dimensions and Mass Rule - as these will affect the vehicle's configuration including the number of axles, deck length and suspension.

Begin by considering the load space requirements when working out the configuration. Engine size doesn't matter - that comes later.

Assess your proposed vehicle's nominal SRT using the default values in the SRT calculator.

The following links take you to information in this site about legal requirements affecting vehicle layout:

• Information for commercial drivers and operators
• Land Transport Rule: Vehicle Dimensions and Mass 2002
• The factsheet 13 series - Vehicle dimensions and mass
• Land Transport Rule: Heavy Vehicles 2004
• Guide to importing motor vehicle into New Zealand
• Vehicle classes, standards and rules

3.Vehicle performance

Overall vehicle performance has a major impact on the success of an operation. Once the basic layout of the vehicle has been decided, the next task is to consider specific factors affecting performance, such as engineering and vehicle components. Some of these are required by law to meet vehicle standards (see Vehicle classes, standards and rules).

Pay particular attention to engine power, torque requirements, transmission gearing, differential ratios, wheels and tyres. You should aim to ensure that there is sufficient power available to handle the work required using the least amount of fuel and with the lowest-possible life cycle costs. Another area to consider is investment in braking technology - for example, ABS brakes can reduce wear on brake pads as well as offering additional safety benefits.

Vehicle performance is also affected by the engine cooling system, exhaust system, air conditioning and other engine and transmission-related equipment.

Fuel efficiency

With fuel typically accounting for over 11 percent of the cost of operating a vehicle, any savings in fuel use can make a significant difference to vehicle operating costs. A saving of 10 percent in fuel costs can affect profitability by as much as 30 percent.

There are a number of ways in which vehicle fuel usage can be reduced:

• The engine size should be carefully selected to closely meet the required demand - bear in mind that every additional 5 hp can increase fuel consumption by two percent.
• Fitting aerodynamic cab deflectors (to help reduce aerodynamic drag) and reducing inter-vehicle spacing can improve fuel efficiency by at least six percent - and in some cases more than 20 percent (depending on the body fitted and the load carried).
• Road speed limiters or cruise control features can result in fuel savings of up to six percent if set correctly.
• Vehicles with semi-automatic and fully-automatic transmissions are gaining favour as they now use the same or less fuel than manual transmissions.

Performance checkpoints

• An engine geared to run at 1450 rpm at 100 km/h uses approximately four percent less fuel than one geared to run at 1600 rpm at the same speed.
• Idling is more common than you may think - in some operations it can add 20 to 30 percent to engine hours.
• A fixed drive fan can use 10 percent of the engine power if it operates all the time, but may only be required for 2-5 percent of the time. Consider fitting electrically-driven thermostatically-controlled fans. Determine whether it is necessary for the fans to turn on automatically when the air-conditioning system turns on.
• At highway speeds, over half the energy required is used to overcome aerodynamic drag. A reduction of aerodynamic drag of 25 percent will reduce highway fuel consumption by 10-15 percent. Reductions in aerodynamic drag of up to 50 percent have been achieved - however, care needs to be taken to ensure the power-train receives sufficient cooling.
• Dead insects behind the front windshield indicate an airflow problem.

4. Health and safety

There are a number of road safety and occupational safety and heath issues that must be taken into account. These can be divided into the following groups:

• Features that affect the normal driving of the vehicle, or its driveability. This includes the vehicle's handling, the effectiveness of the lights and cab layout.
• In-service reliability, to reduce risk of a failure that could cause a crash.
• Active safety features that help avoid a crash occurring should the driver, or another road user, make a mistake. Examples include anti-skid braking (ABS), traction control and road speed limiters.
• Passive safety features that protect the driver and other road users when a severe crash is unavoidable, including safety belts, under-run protection and crashworthy cabs.
• Driver occupational safety and health issues such as the provision of safe access into the cab, the quality of the driver's seat, cab noise, the fitting of tail lifts and other devices.

Other features that can increase safety for your drivers and other road users include daytime running lights and conspicuity tape. Also consider ways of reducing noise and emissions for a healthier working environment both in the cab and around the loading bay. Certification requirements also need to be addressed.

The Land Transport NZ Heavy vehicle visibility code is available from our Helpdesk. Email info@nzta.govt.nz.

When purchasing a vehicle, you also need to ensure all legal requirements are met, as specified in the traffic regulations, the Land Transport Rules and the Health and Safety in Employment Act (HSE).

Safety checkpoints

• The performance of the brakes requires particular attention. Anti-lock braking (ABS), electronic braking systems (EBS) and other brake technologies can significantly improve brake performance.
• Many trucks now comply with the European ECE 29 cab strength requirements, providing the driver with added protection should the vehicle roll or suffer a head-on crash.
• Under-run protection saves lives. Some trucks are now factory-fitted with front, side and rear under-run protection.
• Health and safety considerations are increasingly important now that the cab is deemed to be the driver's place of work.

5.Maintenance

Maintenance is an important consideration when selecting a new vehicle as maintenance (excluding lubricants and tyres) typically makes up 5-10 percent of operating costs. Maintenance costs typically increase as the vehicle gets older and will be higher if the vehicle is routinely operated in harsh conditions.

Infrequent servicing of vehicles may save on maintenance costs in the short-term but is likely to result in breakdowns, which are expensive, not just in terms of repair costs, but in terms of the cost of delayed delivery to your clients.

So, adopt the aim of having zero breakdowns through appropriate vehicle selection and regular maintenance programmes. Ask around to see if the vehicle you are considering is regarded as reliable by other operators. Consider features that improve reliability, such as the use of synthetic lubricants in axles and transmissions and 'sealed-for-life' bearings.

Maintenance checkpoints

• The amount of fuel consumed is a better indicator of engine wear and when to service a vehicle than distance travelled.
• Synthetic lubricants out-perform mineral lubricants at all temperatures. They can reduce fuel consumption by up to 0.5 percent in summer and two percent in winter.
• A 15 psi under-inflation of tyres will increase rolling resistance by six percent.
• Keeping tyres inflated to the manufacturer's recommendations decreases likelihood of tyre blowouts and flats.

6.Appearance

Appearance and functionality of the vehicle can have a significant effect on attracting business and retaining drivers. Consider choosing a cab layout that will enhance driver comfort and a vehicle style which will appeal to your clients (for example, some clients do not like aggressive looking trucks). Vehicle livery and features not only enhance your company's image but can also ensure the driver feels proud of the vehicle and will look after it.

7.Checklist for vehicle specification

The checklist below may provide useful guidance when working out the specifications for your next vehicle.

Operating environment and vehicle layout

Vehicle performance

Health and safety

Maintenance

Appearance

8.Calculating axle weights

Use the axle weights calculator in this guide to calculate axle weights.