I have 4 files named "TraversedEdges_Z1_3_Set1.CSV", "Routes_Z1_3.CSV",  "Volume.xlsx" and "Gravity.xlsx"located at "C:\amir\my project\Python". Your task is to write a Python program using the pandas library to perform the following steps:

1-Read the "TraversedEdges_Z1_3_Set1.CSV" file and load the data into a pandas dataframe.
2-Read the "Routes_Z1_3.CSV" file and load the data into another pandas dataframe.
3-Merge the two dataframes based on the "RouteID" and "ObjectID" columns, keeping all the rows from the "TraversedEdges_Z1_3_Set1" dataframe.
4-Create a new column named "OrigDest" in the 17th column of the "TraversedEdges_Z1_3_Set1" dataframe.
5-Populate the "OrigDest" column with the values from the "Name" column of the merged dataframe.
6-Create two new columns named "Origin" and "Destination" in the 18th and 19th column of the "TraversedEdges_Z1_3_Set1" dataframe.
7-Populate the "Origin" column with the value from "Name" column of the merged dataframe. but only use the date before "-" and populate the "Destination" column with date after "-".
8-Exclude the "ObjectID" and "Name" columns from the final result.
9-Overwrite the original "TraversedEdges_Z1_3_Set1.CSV" file with the updated dataframe, including the newly added "OrigDest" column.
Write a Python program that accomplishes these tasks using the pandas library.