I am using ArcGIS 10.3. The length of my street network is 745127.157m and would like to split this into 10m equal intervals so that I can calculate the slope of each segment. The split tool does not allow beyond 999
There is a proportion tool on the COGO toolbar that will divide a line into equal length segments. You could get close to 10m intervals but it will not work with a basic license. There are several tools on the internet to accomplish this task. Here is one I found on ArcScripts(beta). http://www.arcgis.com/home/item.html?id=d5d27ee47330434b9a96b91136a0118f
If you don't have Standard or Advanced license of ArcGIS to use COGO, then you can use GRASS plugin under QGIS instead of ArcGIS software to split the polylines by specific length. There is a tool "v.split.length - Split lines to shorter segments by length" that can do exactly what you asking, as you can see below:
If QGIS is not installed in your machine, you can find a detailed explanation on how to install QGIS with GRASS in this answer.