Thank you for your shrub question. Arborvitae of this variety are not known to have root systems that jeopardize foundations, but the space you’re planting them in won’t give the plant much room. As the following article says, they not only grow to 12-14 feet tall, but also to a width of 3-4 feet: https://www.thespruce.com/emerald-green-arborvitae-trees-2132081 If they don’t have enough room to spread out, you might face the roots raising the sidewalk in time. Hope this is helpful. Good luck!