If the lane is lethal for kittens, try taking them out on a lead to start with, if when dear Freddy departs this life, you, like me, hold out for six months then are desperate for a new cat.
We took our two present cats with us sailing for three years, where they were only allowed on land if on a lead, (MY rule) they accustomed themselves to it, and lay down beside me on the grass verge of lanes if traffic approached.
BUT unless you have extendable arms, you can only take one cat for a walk at a time. Ours start off nicely, one on either side of me and us all three walking in the same direction. This lasts for all of thirty seconds, then they go off in two different directions and I am left in the middle straining both arms!