“…Sources: US Department of Transportation (2020,2017,2014,2008), Norman (2002), Toor and Salisbury (2014), Ungemah, Swisher, and Tighe (2005), Barton (2014), Cleland and Winters (2000), Khoeini and Guensler (2014), Petrella et al (2014), Burris and Hannay (2003), and Burris and Appiah (2004).…”