I have seen a new invention, a low cost radar speed sign which can be put almost anywhere. It has traffic counts and other metrics. Many companies are using these in their plants to monitor and slow forklift speeds, Lightcast even has a product just for this application forklift radar speed signs - displays - monitors etc. There is even solar pole mounts and small portable carts.
www.forklift-safety-site.com has some good links as well.