The paper presents development of the new Polish method for performing capacity analysis of basic segments of dual carriageway roads (motorways and expressways). The method is based on field traffic surveys conducted at 30 motorway and expressway sites (class A and S roads) in Poland. Traffic flows, composition and travel times were observed in 15-min intervals at each site using ANPR filming method. These data were used to calibrate a family of traffic speed-flow relationships for different roads, based on Van Aerde model. Free flow speed of traffic and road class are the basic parameters defining the speed-flow relationship and the value of capacity per lane in pcu/h. Traffic density was adopted as the measure of effectiveness for defining the level of service. The paper describes derivation of formulae for estimation of free flow speed for different types of roads as well as determination of equivalent factors for converting vehicles to passenger car units. The method allows us to determine capacity and the level of service based on existing or forecasted traffic flow.

Distracted driving is a significant factor affecting road safety and it can occur as a result of using mobile phones while driving. The aim of the current research is to present the prevalence of mobile phone use by Polish car drivers, based on the roadside and online survey. The field study showed that 11.6% of 1867 drivers were using mobile phones while being in motion and 26.1% of 203 drivers when stopped in front of traffic lights. While moving, 8.9% were manipulating the device by hand and 2.6% – holding it to ear. During the stop, 14.2% of the observed motorists were manipulating it, 3.0% – holding it to the ear, and 8.9% – talking through a hands-free or headset. To determine how many people generally use mobile phones while driving (not only during momentary observation), a questionnaire was also carried out. The vast majority of 252 surveyed drivers (82.9%) admitted to using mobile phones while driving, and an equally large proportion considered this behavior as dangerous for transport safety (81.3%). Most of the motorists reported using cell phones: rarely (44.4%), both when stopped and being in motion (58.9%), in a built-up area (63.6%), holding it in hand (43.5%) and in order to chat or write messages (81.8%). The majority of drivers using cell phones while driving were male and in the 25–44 or 18–24 age group. None of the respondents caused an accident due to the use of these devices, but 1.6% were guilty of a collision caused by this reason.