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Page 1

Cost Benefit Analysis of Intelligent Speed Assist

S Doecke, JE Woolley

Prepared by the Centre for Automotive Safety Research

Commissioned by the Department of Transport and Main Roads (QLD)

Co-sponsored by the Office of Road Safety - Department of Premier and Cabinet (WA),

Transport Certification Australia and VicRoads

April 2010

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Cost Benefit Analysis of Intelligent Speed Adaptation

Executive Summary

This report examines the potential costs and benefits of Intelligent Speed Adaptation (ISA) in
Australia. Quantitative results from ISA trials reported in the literature were reviewed and the benefits
of ISA in terms of reducing the quantities such as mean speed, 85th percentile speed and reduction in
speeding identified. The literature also revealed a high variability in these benefits from trial to trial.

An analysis of speeding crashes was conducted using mass crash data collected by the six Australian
states from 2004 to 2008. This analysis was hampered by inadequate identification of speed as a
factor in this data set and inconsistencies between states. Despite these shortcomings, segregation of
this data allowed some general conclusions to be drawn. Speed related crashes occurred in
metropolitan and rural areas therefore ISA should be operational in both areas. Curves were over
represented suggesting ISA incorporating curve speeds should be considered. Young drivers and
motorcyclists were also over represented highlighting the need to ensure these groups of road users
benefit from ISA.

A more detailed analysis was conducted to determine the benefits of advisory, supportive and limiting
ISA. This analysis suggested advisory ISA would reduce injury crashes by 7.7% and save $1,226
million per year. These figures were 15.1% and $2,240 million for supportive ISA and 26.4% and
$3,725 million for limiting ISA.

The costs associated with mapping and the cost of the ISA devices available were investigated.
Mapping the Australian states was estimated to cost $15.6 million with a further $2.4 million per year
required for updating. Only two states have completed maps with another state currently undertaking
the process. Dedicated ISA devices that are currently available in Australia cost between $800 and
$1,800 for a single unit although this could reduce to as little as $200 in two years if a high volume
order were placed. A navaid that has advisory ISA functionality is also available. This costs just under
$30 for a year subscription.

A cost benefit analysis was conducted considering different implementation scenarios including: all
vehicles, new vehicles, fleet vehicles, market driven, heavy vehicles, young drivers and navaid
devices. The cost benefit analysis was heavily influenced by the unit price of the ISA devices causing
the cost benefit ratios (BCRs) to vary from as low as 0.29 to 4.03 over a 20 year timeframe. Payback
periods were also calculated to give an indication of economic benefit independent of a set timeframe
and break even price was calculated to give an indication of economic benefit independent of a set
unit price. Payback periods ranged from 3 to over 100 years and break even prices from $341 to
$2,164 per unit. The “all vehicles” and “new vehicles” scenarios produced the greatest BCRs although
it was thought that, taking into account the elevated risk of young drivers, a combination of
implementing ISA on young driver’s vehicles and new vehicles may be the most cost effective
implementation scenario. The navaid scenario suggested that even if these devices are only
infrequently used and less effective than dedicated devices they may still prove a cost effective option.
Limiting ISA generally produced the highest BCRs therefore this level of ISA should be implemented
wherever possible.

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Cost Benefit Analysis of Intelligent Speed Adaptation

3.2.6 110 km/h zones

The risk curve for 110 km/h zones is shown in Figure 3.9. It was based on the mean speed of the
speed distribution without ISA (102.9 km/h).

Figure 3.9
Risk curve applied to speed distributions for 110 km/h roads.







70 80 90 100 110 120 130 140 150

Speed (km/h)




Figure 3.10 shows the results of the analysis described in Section 3.2.2 for 110 km/h zones. It is clear
from the speed distribution with no ISA that there are distinct differences in the measurement sites that
result in double peak in the distribution. The peak just over the speed limit produced by limiting and
supportive ISA was greater than at the lower speed limits.

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Cost Benefit Analysis of Intelligent Speed Adaptation

Figure 3.10
Speed distributions with and without ISA for 110 km/h zones







70 110 150

Speed (km/h)









3.2.7 Risk reduction and savings

After the distributions with and without ISA were determined (for example Figure 3.10) the proportion
in each 2km/h band was multiplied by the risk at the average speed for that band (for example Figure
3.9). The results for each speed band were then summed to produce a total injury crash risk. The
percentage reduction in the injury crash risk was then determined for the particular level of ISA. Table
3.7 shows the percentage injury crash risk reduction at different speed limits relative to the level of ISA
implemented. Of interest is the difference between supportive and limiting ISA given the similar
distributions. This highlights the risk reduction produced by ensuring that it is impossible to speed by
more than a few km/h. Advisory ISA appears most effective in 80 and 100 km/h zones while
supportive and limiting ISA excelled in 50 and 100 km/h zones. Generally limiting ISA was the most
effective at reducing crash risk, followed by supportive ISA with advisory ISA being the least effective.
80 km/h zones provided the exception to this rule as advisory ISA was found to be more effective than
supportive ISA, albeit marginally so.

Table 3.7
Percentage injury crash risk reduction by level of ISA and speed zone

Speed Limit (km/h) Advisory Supportive Limiting
50 6.5% 19.6% 42.4%
60 2.1% 9.4% 15.8%
80 14.4% 12.3% 23.3%

100 17.3% 28.8% 35.9%
110 4.6% 12.4% 21.7%

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Cost Benefit Analysis of Intelligent Speed Adaptation

Jamson S (2006), ‘Would those who need ISA, use it? Investigating the relationship between drivers’
speed choice and their use of a voluntary ISA system’ Transportation research part f, 9, pp. 195-

Jamson S, Carsten O, Chorlton K, Fowkes M (2006) Intelligent speed adaptation literature review and
scoping study. Leeds: Institute for Transport Studies, University of Leeds and MIRA Ltd

Kloeden CN (2009) Vehicle speeds on Queensland roads – May 2009, Adelaide: Centre for
Automotive Safety Research.

Kloeden CN, McLean AJ, Glonek G (2002) Reanalysis of travelling speed and the risk of crash
involvement in Adelaide South Australia, CR 207, Adelaide: Road Accident Research Unit for
Canberra: Australian Transport Safety Bureau

Kloeden CN, McLean AJ, Moore VM, Ponte G (1997) Travelling speed and the risk of crash
involvement, CR172, Canberra: Federal Office of Road Safety, Transport and Communications.

Kloeden CN, Ponte G, McLean AJ (2001) Travelling speed and the risk of crash involvement on rural
roads, CR 204, Adelaide: Road Accident Research Unit for Canberra: Australian Transport Safety

Kloeden CN, Woolley JW (2009) Vehicle speeds in South Australia 2007, CASR051, Adelaide: Centre
for Automotive Safety Research.

Lahrmann H, Agerholm N, Tradisauskas N, Berthelsen, K Harms, L (in press) ‘Pay as you speed, ISA
with incentive for not speeding, results and interpretation of data’, Accident analysis and

Lahrmann H, Madsen JR and Boroch T (2001) ‘Intelligent speed adaptation — development of a GPS
based ISA-system and field trial of the system with 24 drivers’ in Proceedings of the Eighth World
Congress on Intelligent Transport Systems, Sydney, Australia, 30 September–4 October.

Lai F, Chorlton K, Carsten O (2007) ISA – UK: Overall field trial results. Leeds: Institute for Transport
Studies, University of Leeds and MIRA Ltd

Litman TA (2009), Transportation cost and benefit analysis, techniques, estimates and implications,
viewed 1 March 2010, <>

Lancashire County Council 2009, ISA trial on the move, Lancashire County Council, Lancaster, 11

MUARC (2008) Safer Vehicle Purchases: Developing cost-effectiveness estimates for fleet managers
and others – Part A: Crash profiles and risk estimates, AP–R324/08, Monash University Accident
Research Centre for Sydney: Austroads.

New South Wales Centre for Road Safety. (2008) Road traffic crashes in New South Wales 2007.
Sydney: New South Wales Centre for Road Safety, Road Traffic Authority.

Oei HL, Polak PH (2002), ‘Intelligent speed adaptation (ISA) and road safety’ International association
of traffic and safety sciences research, 26(2), pp 45-51.

Päätalo M, Peltola H, Kallio M (2001). ‘Intelligent speed adaptation-effects on driving behaviour’ in
Proceedings of Traffic Safety on Three Continents Conference, Moscow, Russia, 19-21
September 2001.

Pallas T (Minister for Roads and Ports) 2010, Trial of new technology to slow down speeding drivers,
Vicroads, Melbourne, 13 January.

Regan RA, Young K, Haworth N (2003) A review of literature and trials of intelligent speed adaptation
devices for light and heavy vehicles. Monash University Accident Research Centre for Sydney:

Regan M, Young K, Tomasevic N, Mitsopoulos E, Tierney P, Healy D, Connelly K, Tingvall C (2005)
‘Final results of a long-term evaluation of intelligent speed adaptation, following distance warning
and seatbelt reminder systems: system and interactive effects’ in Proceedings of 12th World
Congress on ITS, San Francisco, United States of America, 6-10 November 2005.

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Cost Benefit Analysis of Intelligent Speed Adaptation

RTA (2009) Annual report. Sydney: Roads and Traffic Authority.

Tate F, Carsten O (2008). ISA – UK: implementation scenarios. Leeds: Institute for Transport Studies,
University of Leeds and MIRA Ltd

Taylor GW (2006). Speed choice and modelling of the impacts of speed on safety and the
environment, Ontario: G.W. Taylor Consulting

Transport for London (TfL) 2009, TfL announces trial of intelligent speed adaptation, TfL, London, 11

Várhelyi A, Hjälmdahl M, Hydén C, Draskóczy M (2004), ‘Effects of an active accelerator pedal on
driver behaviour and traffic safety after long-term use in urban areas’, Accident analysis and
prevention, 36, pp. 729-737.

Várhelyi A, Mäkinen T (2001), ‘ The effects of in-car speed limiters: field studies’, Transportation
Research Part C, 9, pp. 191-211.

Vlassenroot S, Broekx S, De Mol J, Int Panis L, Brijs T, Wets G (2007), ‘Driving with intelligent speed
adaptation: final results of the Belgian ISA-trial’, Transportation Research Record Part A, 41, pp.

Wall JP, Job SRF, Boland P, Cuenca V, Creef K, Beck J, and Saffron D (2009) ‘The New South Wales
intelligent speed adaptation trial’ in Proceedings of the Intelligent Speed Adaptation Conference,
Sydney, Australia, 10 November 2009.

Wundersitz LN, Doecke S, Baldock M (in press). Annual performance indicators of enforced driver
behaviours in South Australia, 2008. CASR Report Series CASR058. Adelaide: Centre for
Automotive Safety Research.

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