Traffic signs have been around and used for a long time. In fact, the United Kingdom and the United States are among the first countries in the world to put up traffic signs to alert drivers and enforce traffic laws. Nevertheless, as noted by (Keong et al., 2018), there are some problems related to typical traffic signs, including
(a) poor visibility of traffic signs,
(b) the challenge of placing signs, and
(c) difficulty remembering the highway code.
There are more than 60 signs in the United States and 170 signs in the UK highway code for reading and memorization, which makes it an arduous task for amateur drivers and those with poor memory.
The idea of wireless digital traffic signs is to set up a server on the traffic signboard. Then, the special signal is transmitted wirelessly to the approaching traffic. A car receiver then gathers the wireless signal and warns the driver (orally or on the screen). This completely eliminates the need for the driver to take care of signs while driving and he can concentrate on the events ahead of him. Transportation networks can take advantage of using this new wireless traffic signage system through these cases (Toh et al., 2020):
(i) There is no need for signs to be visible to humans,
(ii) It reduces the driver's workload to be aware of the signs during driving,
(iii) it eliminates the driver’s arduous task of remembering all the traffic signs;
(iv) Adverse weather and poor lighting conditions cannot have significant impacts on these signs.
(vi) There is no need for complicated signal processing and visual traffic sign recognition employed in autonomous vehicles,
(vii) it can assess traffic volume automatically, and
(viii) its cost is relatively low.
There may be several digital wireless traffic signs on the road. Thus, signal orientation is crucial because signs are being used for approaching vehicles. Vehicles should no longer be affected by the signs they have passed. Therefore, the transmitted signals can be conducted to the approaching vehicles in all lanes of one direction. Furthermore, this novel framework can lead to the introduction of several new applications including automatic traffic volume measurement and automatic detection of traffic violations (Keong et al., 2018).
Usual ways of detecting traffic violations are implemented through simple pre-installed cameras and speed radar detectors with white line markings on the roads. These methods are less beneficial under inclement weather conditions due to poor visibility. One of the newest methods to detect traffic violations is the presence of wireless digital traffic signs (Keong et al., 2018). This way, drivers can no longer deny or overlook the existence of signs for traffic law enforcement, because the received and audio signs are recorded as proof in the advanced driver-assistance systems (ADAS) user system as well as in the car black box. Driving at the specified speed limit violates the traffic code, and the digital traffic sign warns the traffic citation system, which can then send the traffic citation directly to the driver through remote communication. On the other hand, the digital traffic sign can transmit the violation warning directly to the driver in conjunction with a copy of the traffic citation system. The wireless traffic sign data received by the driver is recorded as evidence of successful notification and the driver cannot deny getting it. This procedure can be accomplished automatically and seamlessly.
Therefore, it will improve the effectiveness of the traffic violation prohibition system (Toh et al., 2020). One of the leading countries employing smart traffic signs in its transportation networks in the UK. In 2019, the UK installed novel wireless traffic signs on its roads. This signage system created by cooperation between two companies (i.e., Costain and Swarco), is able to show live images of upcoming congestion on the road (SmartCitiesWorld news team, 2019). These signs are technically advanced and obviously, have graphics and text that drivers can see. It is easy to rapidly understand the messages transmitted by these signs, and they are able to inform drivers of road conditions. These new signs, in addition to increasing the road experience for drivers, cost less to preserve than conventional indicators. New signs need fewer materials and cabling, leading to less construction time, maintenance, and cost (Work Safe, 2020).
Another pioneer in using smart traffic signs on its roads is the USA. So, it is worth investigating the new active traffic management (ATM) signs implemented in Las Vegas as an example. Although Southern Nevada has incorporated dynamic and conventional traffic signs for years, the Neon Project ATM signs are much more advanced and provide cutting-edge driver information in real-time. ATM signs can dynamically control traffic congestion based on common traffic conditions using data like the mean speed for each lane of travel, which can be collected through loop detectors across the corridor. After analyzing the aforementioned data, ATM signs give drivers some information about road conditions. Furthermore, closed-circuit TV (CCTV) images across the corridor give additional data enabling system conductors to detect and respond to incidents and congestion. The ATM signage system has achieved such success that more exploitation of this technology is arranged for the Las Vegas valley thanks to the US department of transportation for its $ 6 million financial aid (Maynard, 2021).
Although these state-of-the-art traffic signs can provide transportation networks with several benefits, they have still some shortcomings that should be addressed (Keong et al., 2018). First, digital wireless signs should be able to work properly even under inclement weather conditions. So, they should be tested under these conditions.
Moreover, the traffic sign messages relayed to the vehicles should be authenticated and secured to prevent hackers from making chaos on the streets. There is currently no global standard regulating transmitted wireless traffic sign signals. However, it is probable to happen in the not-too-distant future to ensure law enforcement and adequate safety for road users.
Furthermore, the server and receiver rules should be set in the future. Future cars, via their ADAS or navigation warning system, synchronize with traffic sign signals and show the relevant messages to the driver through an in-car display terminal. In addition to the signs displayed on the car monitor, the sound is added to give a warning to the driver. Therefore, it is anticipated that future vehicles will have pre-confirmed electronic elements to analyze road signs safely and securely.
Keong, T., Cano, J., Fernandez-Laguia, C.-J., Manzoni, P., Calafate, C., 2018. Wireless Digital Traffic Signs of the Future. IET Networks 8. https://doi.org/10.1049/iet-net.2018.5127
Maynard, M.J., 2021. INTELLIGENTLY MANAGING TRAFFIC WITH ADVANCED DYNAMIC MESSAGE SIGNS [WWW Document]. Roads Bridg. URL https://www.roadsbridges.com/intelligently-managing-traffic-advanced-dynamic-message-signs-0
SmartCitiesWorld news team, 2019. UK installs next-generation digital signage on its roads [WWW Document]. URL https://www.smartcitiesworld.net/news/news/uk-installs-next-generation-digital-signage-on-its-roads-4499
Toh, C.K., Sanguesa, J.A., Cano, J.C., Martinez, F.J., 2020. Advances in smart roads for future smart cities. Proceedings. Math. Phys. Eng. Sci. 476, 20190439. https://doi.org/10.1098/rspa.2019.0439
Work Safe, 2020. How Smart Road Signs Improve Our Way of Life [WWW Document]. Traffic Control Ind. URL https://worksafetci.com/2020/04/how-smart-road-signs-improve-our-way-of-life/