Highway Design and Safety Consequences: A Case Study of Interstate Highway Vertical Grades

Table 3

Maximum length (mi) for a certain grade with design speed of 70mph.

Vertical Grade (%)	2%	3%	4%	5%	6%
China	–	0.6214	0.4971	0.3728	–
Iran	0.1705	0.0947	–	0.0568	–
Japan	–	–	0.1326	0.0947	0.0758
USA	–	0.5592	0.3728	0.2920	–