Conclusions

General

This study has established evidence that kerbs of different heights and profiles are detected and traversed differently by people with varying abilities. There is now evidence of the contradiction between the needs of visually impaired users and physically impaired users.

For visually impaired participants, the kerb height with the least workload for detection depended on whether the user utilise a cane or a guide dog, or had some vision. Kerbs of 20mm and 25mm were detected, but 50mm was universally and, often noticeably, easier to detect.

However, for those with physical movement challenges, kerbs higher than 50mm caused problems, especially when using wheelchairs or other supportive devices. Kerbs of 20mm and 25mm were preferred to higher kerbs.

Both participant groups, and the baseline, agreed that kerbs with a 100mm upstand were more difficult to cross.

The result from this study backs up the qualitative evidence established in the previous phases of this research study.

The clearest finding of the qualitative outcomes across all phases of this study was that street users find traversing kerbs to be dangerous, physically demanding, frustrating and occasionally frightening. They anticipate technologies, such as mapping apps, which may assist them, but they frequently fall back on carers for assistance. This reduces their ability to leave the house and travel, preventing them from accessing many aspects of society. There is now evidence on kerb heights which could improve this situation.

From these Phase 4 results it was calculated that a kerb upstand in the range of 40mm - 48mm could be of equal workload for both visually impaired and physically impaired user groups. Considering engineering standard tolerances this would translate 40mm or 45mm upstand. However, further testing would be required before any suggestion to recommend these kerb upstand heights in guidance could be made. This report does not set recommendations for statutory bodies but presents information and conclusions which can be used by them to determine the future guidance.

When considering the policy and guidance implications in these results it will be important to remember that all kerbs tested required a level of effort from the participants to traverse; mental and physical. Under real world conditions it is likely that such manoeuvres will be undertaken several times a day under more stressful and hazardous conditions. When establishing kerb upstand guidance, it will be important to consider what would be an acceptable workload compromise based on the intended design objectives and environment.

Areas for Further Study

During this course of the research study avenues for further research were identified, these included: 

• Further user testing with both the Vision and Physical capability groups on 40mm and 45mm kerbs.
• Testing of Cycle segregation Kerbs due to their increasing usage.
• Testing of bespoke kerb profiles to determine if changes in this parameter could assist impaired users.
• Research into lighting dependent challenges (e.g. day and night).
• Research into different weather conditions, including wet and frozen conditions.
• Research into the possibility of enhancing kerbs for those with moderate visual capability levels (e.g. using colour and contrast).
• Research covering a wider range of ages, demographics, and capability variations.
• Research covering different mobility aids (motorised wheelchairs).
• Research into participant fatigue – how detecting, crossing or traversing multiple kerbs or street obstacles over time affects workload perception.
• Research into the design and frequency of controlled and uncontrolled crossings.
• Research into improved wheelchair designs for mechanical stability and kerb crossings.