System reliability

4.4.6.1 Inaccurate route guidance received and followed

Only 15% of respondents thought that routing instructions generated by their navigation systems were always completely reliable. 82% reported that they had received route guidance instructions that were inefficient or wrong and 42% reported that they have received inaccurate instructions that were dangerous or illegal. Nearly a quarter of these respondents (23%) admitted to having followed dangerous/illegal instructions on at least one occasion. Dangerous or illegal route guidance instructions that respondents have both received and followed are illustrated generally in figure 4.12 and more specifically in table 4.4. Bold text in table 4.4 represents inaccurate instructions respondents have followed.

Specific examples noted by respondents of inaccurate instructions they have both received and followed (also shown in bold) are highlighted in table 4.4.

Those who had followed them were significantly older (t(101.8)=2.35, p<0.05) and held their driving licenses for significantly longer (t(83.5)=2.784, p<0.01) than those who had not. 73%

of them were over the age of forty. Following dangerous or illegal route guidance instructions was not significantly associated with navigation system type, navigation system experience, driving experience, computing skill or any other demographic variables.

More than a quarter of respondents (28.7%) have also received information from their IVNS, which has led to them travelling to an incorrect final destination, and this has happened to just over 40% of these respondents on more than one occasion. In the final questionnaire

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think about the last time it happened and attribute blame. The majority of respondents reported that the system was at fault (57.5%), about a fifth blamed themselves (18.9%) and about a quarter (23.6%) blamed both themselves and the system.

Figure 4.12 Tree diagram highlighting contexts in which drivers have followed inaccurate route guidance instructions (N=872)

Do you think that the routing instructions generated by your navigation system are always completely reliable?

(N=872)

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have received and followed inaccurate route guidance instructions (N=778)

Routing problem Specific routing problems Specific examples based on participants’ comments

No entry/one way street tells me in my own neighbourhood to drive into streets that do not exist suggested taking a slip road on a motorway that has been blocked off for

turn at non-existent street drive to a dead-end

Private road/ road for restricted vehicles 51%

** 19%

Routed into Pedestrianised zones and other city areas cars are not

Routed onto a Private road or road for emergency vehicles only (8%) Routed down public footpaths across a field no vehicle access possible (style through a hedge)

the system frequently directs me along footpaths

Bicycle path Frequently routes along farm tracks

Vehicle restrictions 3%

** 1%

Width restrictions (7%) Routed down extremely narrow roads

Frequently routes along unusable non-vehicular narrow tracks / lanes Width and weight restriction Weight restrictions (1%) through weight limits

Height restrictions (1%) under low bridges Other vehicle unsuitability issues

(3%)

Drive down steep narrow road with 180 degree bends not suitable for large vehicles

Routed me down streets that were not acceptable for the vehicle we were in.

Directed onto HOV section of beltway in Washington DC / Illegal but not dangerous

Instructed to perform prohibited manoeuvres such as U-turn, Lane Reverse direction at a Motorway junction that did not allow reverse directions (in France) Other

11%

** 4%

System efficiency issues system occasionally does not give sufficient warning to move into freeway exit lane before manoeuvre directed to the wrong address in opposite direction Sometimes it will specify a roundabout when in fact its a junction route causes a drive through town centres rather than take the by-pass or ring road Does not inform me where route is interrupted by natural or man made obstacles or detours or where street name changes enroute

* Percentage of participants who have received dangerous/illegal instructions

**Percentage of all participants

Bold text represents dangerous/illegal route guidance instructions that participants have followed.

Bold percentage represents percentage of those who have followed dangerous/illegal route guidance instructions

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Most respondents who have received inaccurate route guidance instructions had never updated the map on their navigation system (58%), although a significant proportion had (42%). Figures 4.11 & 4.12 highlight some of the reasons why respondents had or had not updated their maps. Those who had purchased a map update were significantly older (mean

= 47.7 years) than those who had not (mean = 42.5 years) (t(713)=2.878, p<0.01).

Respondents had their current map installed for an average of 10 months, although there was a wide range (0-84 months). A fifth of respondents who had not updated their maps would not consider updating in the future or were unsure. Most of those who updated did so once a year or more than once a year (61%), although more than a third updated once every 2 years or more (39%). There was a significant positive correlation between the frequency with which respondents reported updating their maps¹ and the number of months they have been using their system (Spearman-rho=0.24, df=307, p<0.01) as well as the cost of updating (i.e. respondents that thought it was very expensive tended to update their maps less frequently). (Spearmans-rho= 0.231, df=307, p<0.01).

Figures 4.4 and 4.5 above show that about a fifth (22%) of respondents particularly liked their systems (re)routing/ mapping capabilities, but that over a quarter (28%) particularly disliked these system capabilities. However, 52% of those who particularly disliked them had never updated the map on their navigation system, although 84% indicated they would update sometime in the future.

1 This variable ranged from very frequently to very infrequently (see appendix F).

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their IVNS (N=441)

16%

15%

8%

23%

18%

5% 7% 8%

Holiday or trip/ change of address Manufacturer advice

Advice from other sources Awareness of roadworks

Previously given inaccurate instructions

Free/ warranty/ part of software or hardware upgrade Like to keep up to date

Other (inc. gift, extra features in new maps))

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on their IVNS (N=550)

1.5 Discussion