The R40 begins in Adenta, branching off the N4 as the Accra-Dodowa Road. This section is known as the Adenta-Trom section. It heads through Frafraha and Ashieke to Amrahia, where a toll booth is located. It then continues through Oyibi and Bawaleshi to Dodowa, where the R13branches off from the R40 to the east.
After Dodowa, it courses through the Eastern Region to Ayikuma, just over the border, then back into Greater Accra. It then goes to Amanfro before leaving the region once more.