How top open a Civil model made in 2018 version in a 2017 version Civil?

There is no other way but to use MCT file. Here are the steps to follow:

1. Open the model file with Civil 2018.

2. Export the model into the text file using the File>Export>MIDAS Civil MCT file function.

3. Run Civil 2017.

4. Execute the Tools>MCT Command Shell function.

5. Open the text file saved in the step 2.

6. Hit the Run button and you will see the error messages.

7. Go to the place where the error is happening and delete the data.

8. Hit the Run button again.

9. Repeat the step 7 and 8 until no errors are found.

10. Close the MCT Command Shell and restore the deleted data manually.