# Road Infrastructure Challenges Faced by Automated Driving: A Review
## 4 Identification of Challenges
### Maintenance  
Ensuring sufficient visibility of the traffic signs and road markings through proper maintenance is one of the important tasks of road authorities. With the penetration of ADASto the market, maintenance become even more relevant, as ADAS requires clearly visible and unobstructed road infrastructure. This means that reflectivity and the contrast ratio should be kept within the range at which reliability of the ADAS is ensured. Moreover, road authorities should regularly repair damage and remove natural obstacles, such as bushes or snow. Therefore, there are a few questions we can ask ourselves when it comes to maintenance:  
* What are the minimum thresholds and important parameters for good visibility? * How can potential issues be detected in time? * What influence does digitalisation have on maintenance? * Will the costs of maintenance increase? To investigate the implications of the road infrastructure for MV, many countries and organisations around the globe have already conducted extensive research [9; 10; 11]. Their findings are provided in previous sections through Tables 5 and 7, which summarise the proposals for good detectability of the parameters, such as visibility, colours, width and material of the road markings and traffic signs. However, the maintenance periods cannot be generalised. Each region, even if it belongs to the same jurisdiction, can have certain characteristics that make it an exception. Such examples are alpine roads that, due to harsh winters and frequent shwelling, experience fast deterioration of road markings, which is especially important in discussions about more advanced technology, such as profiled markings that are beneficial under wet or rainy conditions. With digitalisation and further advances in automated driving, real-time maintenance, updates of digital maps and warning of obstacles ahead will be of huge importance. Information on the local road conditions is of high interest for automated driving functions that have to adapt their strategies, such as distance to other traffic participants and the decision making concerning braking and steering interventions to the coefficient of friction between tire and road. The potential of combining vehicle and infrastructure data, e.g., for maintenance, is shown by [76] and with weather data by [77]. This offers both opportunities and additional tasks for road authorities. To ensure the proper operation of ADAS, especially concerning higher levels of automation, the road should be subjected to stricter maintenance, which means all obstacles, ghost markings, potholes, etc., must be recognised and addressed in a timely manner. It is hard to imagine that it will be possible for all roads to be inspected simply though road monitoring by authorised vehicles. Therefore, information could be collected through public and private transport via crowdsourcing [43; 44]. Whether this will completely relieve road authorities from the burden of manually updating databases, and to what extent collaboration between road authorities, map providers and vehicular manufacturers regarding data transfer remains a necessity, but this is more a subject of digitalisation than maintenance. Crowdsourcing will, however, certainly reduce some of the expenses associated with monitoring but, in general, a reorganisation of operation activities of conventional road authorities is needed. Digitalisation will involve additional expenses for maintenance, installation as well as a need for new expertise. At the same time, shared mobility tends to reduce the number of vehicles, which could lead to increased maintenance periods, but at this point it is very hard to forecast in which direction traffic will develop. Maintenance is a complex challenge in which the burden is mostly placed on road authorities. Yet, it is still too early to precisely define the required actions. As support in performing their task, policies could be a good way to define clear guidance.