 The segment between Highway 406 in Thorold and Niagara Road 57 east of Thorold is a four @-@ lane freeway . It also contains the Thorold Tunnel , one of the three tunnels under the Welland Canal . The remaining segments vary between a two @-@ lane rural highway and four @-@ lane urban roadway . Overall , the highway is 15 @.@ 5 km ( 9 @.@ 6 mi ) in length , with a 18 @.@ 1 @-@ kilometre ( 11 @.@ 2 mi ) gap separating the two sections . 
