# Optimal Longitudinal Texture on Concrete Pavement to Reduce Lateral Vibration of Vehicles
## 1 Introduction  
In 2006, a survey was conducted in South Korea on the importance of road services and the problems related to pavement by expressway users [1]. The survey showed that road surface condition is the most important factor; in particular, drivability according to surface conditions such as the likelihood of skid resistance and noise accounted for more than 50% of the survey result. Subsequently, the Korea Expressway Corporation (KEC) introduced and has been applying longitudinal timing as a surface texturing method to improve driving comfort and reduce noise [2]. Longitudinal tinning has a slightly lower skid resistance than lateral timing, but it surpasses the minimum coefficient of friction standard. Moreover, it has a higher noise reduction and drivability than lateral timing, thereby increasing comfort for road users. Recently, however, users have raised complaints of lateral vibrations while driving in longitudinal tinning sections. Although KEC has improved the longitudinal tinning specifications, complaints have nonetheless been raised intermittently in certain sections even after the improvement [3]. Representative factors of lateral vibrations in longitudinal texturing sections include the texture specifications of pavement surfaces and the tire specifications of vehicles, and the degree of vibrations depends on the combination of these factors. In South Korea, during the early stage of the introduction of longitudinal tinning, coarse aggregates used to get detached due to tinning specifications being narrower than the maximum coarse aggregate size (25 mm or 32 mm) of concrete pavement [4]. Hence, the method of arbitrarilyincreasing or decreasing the center-to-center interval of longitudinal timing was used at the construction site. However, even still, lateral vibrations have continuously been reported. Consequently, longitudinal thinning was removed through diamond grinding in more than half of the sections in which it was previously applied. Subsequently, a study was conducted to address this problem, and it found that the larger the timing width, the higher the probability of lateral vibrations, and that a intning width of 2 mm could help avoid lateral vibrations in all vehicle types [5]. For the intning center-to-center interval, initially, a distance of 21 mm had been applied; however, now 19 mm is being applied, which is the same as in the U.S. However, it was found that test sections of 16 mm generated fewer lateral vibrations than the 19 mm sections, although the intning width and center-to-center intervals need to be finalized after reviewing the practicality of field application. [PERSON] investigated the effects of tire patterns and pavement surface on groove wandering and found that the lateral stress in the equal-interval grooving section decreased as the center interval became larger and it increased with the groove width [6]. It was confirmed that the center-to-center groove interval had a greater effect than the groove width. Recently in South Korea, Next Generation Concrete Surface (NGCS) with a width of 3-4 mm, depth of 3-5 mm, and center-to-center interval of 13-16 mm has been applied to improve driving comfort and safety of drivers in tunnels [7]. However, lateral vibrations were reported in these sections as well. The California Department of Transportation (USA) is also limiting the groove width to 3.2 mm and the center-to-center interval to 19 mm due to the occurrence of lateral vibrations in NGCS sections [8]. Lateral vibrations in tires are caused by the imbalance among lateral forces when the pavement texture and tire tread are in contact. Grooves and tread blocks, which are in direct contact with the pavement texture, have a high correlation with lateral vibration [6]. Furthermore, the influence factor of the tire part has the closest relationship with the groove because the imbalance of lateral stress increases if the interface between the block and groove is caught in the intning groove of pavement [9].