A network dataset models a road with both sides of travel. Based on the direction of digitization, cost of travel can be specified on the From-To and To-From directions. Normally when you set up a cost attribute, you specify the two fields on the feature class that provide these two costs. As long as you can set up the values for the uphill/downhill costs, they can be loaded into the network and the Service Area solver will be able to use them. When you solve the Service Area you can specify the travel direction as From the facility or To the facility. That will use the appropriate direction of the slope costs into account.
The setting up of the data and the network dataset can be done with the Pro 2.5 using the property pages of the network dataset. The main problem in setting up these cost fields will be loading the two fields (From-To and To-From) correctly from your DEM. You may need to do some scripting for that aspect.
Jay Sandhu
