Under the £2.6m deal, WSP will provide engineering and design services on the M62 Junction 20 to 25 linking Yorkshire and Lancashire, and the A1 (M) Junction 6 to 8 near Stevenage.
Both sections are being converted into all lane running, permanently converting the hard shoulder into a running lane to add capacity.
The 31km stretch of the M62 through the Pennines will become four lanes on each carriageway while the A1(M) will be upgraded to three lanes around Stevenage.
Other smart motorway schemes currently involving WSP include the M4 (J3-12); M6 (J21a-26); M27 (J4-11), and M62 (J10-12).
WSP also worked on the 32-mile stretch of the M1 between junction 28 near Mansfield and junction 35a north of Sheffield, in collaboration with contractor Costain. This £330m project, which opened in 2017, is the longest smart motorway section implemented to date.