If you are using these for approval from a jurisdiction or to demonstrate that a particular vehicle can make a certain turn, I would highly recomend AutoTURN over using any blocks as AutoTURN is based on the AASHTO design guides and will better support your demonstration. Additionally, I have seen drawings where blocks were used and I was told that a firetruck etc... could make the turn with no problem but when I ran AutoTURN on it, I found that the vehicle behaves differently than what you would get by just laying a block accross a site plan driveway.
They have tutorials to teach you how to use it and it is quite simple to learn. We have generated extra design work from other Architectural and Civil firms by having this ability to test their site.
Good luck.