The economic impact of enforcing axle load regulation - the case of Zambia

The economic impact of enforcing axle load regulation - the case of Zambia


Odd I. Larsen, Anne Kjerkreit, James Odeck


Møreforsking Molde AS


Norwegian Public Roads Administration









This study is an economic assessment of regulating and enforcing axle load control of heavy vehicles in Zambia. This enforcement is part of a wider Axle Load Control Programme to prevent premature deterioration of roads and bridges, implemented in 2004 with a time frame of fours years. Among the many objectives of the programme, a new regulation pertaining to maximum permissible axle loads and gross vehicle mass (GVM) was approved in 2007 and included in the Roads Act.

Efficient enforcement of axle load regulations will have two major impacts: (1) Heavy axles (as measured by GVM) inflict an excessive cost in terms of wear and tear on the roads. They may cause additional damage to bridges and impede the safety of traffic. Thus, efficient axle load regulation will lead to a reduction in maintenance cost to the road keeper, i.e., the government. (2) On the other hand, enforcing a strict regulation will imply that excessive payload on overloaded vehicles must be transported by additional vehicles and hence increase vehicle-kilometres driven by heavy vehicles. These added vehiclekilometres will increase the cost of moving any given volume of goods for road hauliers. The costs associated with this second impact may to some extent counteract the gains associated with reduced wear and tear on roads. The economic assessment has therefore focused on these two major impacts, rather than on the total Axle Load Programme per se.

The results of this study are:

The enforcement of the axle load regulations will lead to savings in the cost of road maintenance for the road keeper (the Zambian government). The savings will be manifested in longer time intervals between rehabilitation of different road segments. The average annual savings are estimated to be of the order US $4-4.1 million per year. Discounted over 15 years with 6 per cent rate of interest, this amounts to a present value of US $41 million. Thus, in terms of future savings in road maintenance, the programme is profitable.

However, the estimated increase in annual road haulage cost is estimated to be of the order of 12-13 million US $, i.e. about three times the savings in road maintenance. Excluding transit traffic, the added cost of road haulage is a cost to producers and consumers in Zambia. The current GVM limit of 56 tonnes is an improvement over the limit of 55 tonnes. The 12-13 million US $ represent potential savings from increasing the GVM limit even further, to the more realistic 60 tonnes.

The main reason for the high increase in the cost of road haulage is the GVM regulation. The regulation effectively constrains payload per trip for heavy goods vehicles. The weight of very heavy goods vehicles generally exceeds the recently approved GVM limit of 56 tonnes before the axle load restrictions come into force. Thus, the GVM regulation by itself has a negligible impact on road wear when the axle load regulations are efficiently enforced.

The newly approved maximum GVM of 56 tonnes is expensive for Zambia in terms of transport costs, although it is an improvement over the previous regulation of 55 tonnes. However, it is worth noting that the limit is set regionally by SADCC, mainly as precaution for bridges, and not by Zambia alone. Because a higher GVM limit would be less expensive, the proposal to gradually increase the limit is a move in the right direction. It has not been possible to evaluate the optimal GVM for Zambia, due to the fact that information on the strength of bridges in Zambia is very scarce. The need for data on bridges should be stressed.

Finally, the quality of data from the baseline study of 2002 - 2004 and from the benchmark study of 2005 has been good relative to that of other developing countries. However, there is room for improvement. We recommend the programme improves the quality of data collection, especially with respect to origin and destination of vehicles and types of goods transported. Further, the programme should ensure that measurements are both precise and representative.

While the effect on road deterioration is the main motivation for a programme attempting to reduce overloading, the programme may have additional benefits, depending on the specific circumstances. These would include: (i) A comprehensive scheme with efficient weighbridges will provide valuable information on the roads exposure to heavy traffic. In the future, this information can be used in the design of maintenance programmes and to set the appropriate design parameters for roads to be built or rehabilitated, (ii) Training of officers both in administration and operation of the control scheme contributes to a general improvement of skills for the workforce, (iii) The programme can contribute to a more general awareness of the corruption problem and set an example in this respect, (iv) Information about programme and its objectives can improve the general awareness of truckers when it comes to problems caused by overloading, (v) The programme will promote fair and efficient competition in the trucking industry by not given a competitive advantage to operators that dont comply with the rules and regulations pertaining to loading of vehicles, (vi) Depending on the level on non-compliance with the regulations, the fines collected from overloaded vehicles may generate revenues exceeding the cost of operating the programme and thus provide additional funding for road maintenance. However, if the programme is efficient, the rate of compliance will - in the longer run - be high and the revenue consequently low.

These additional benefits have not been possible to measure in monetary terms and will only occur if the programme continues in the future with the intended level of efficiency. If that happens, these benefits alone may well outweigh the negative impacts of the programme which are the extra costs imposed on road hauliers due to GVM restriction. Our observations are that these benefits are currently being realised as the programme moves forward.