On the page for each fort you’ll find the addresses can be used to create a route description. Your travel choices are: by car, by public transport, by bike or by foot. In addition, the page for a fort tells you if the fortress is accessible by wheelchair. You can also search directly which route to take via : https://maps.google.nl/maps.
Bicycles can be rented at many train stations, including ones in the vicinity of the Defence Line of Amsterdam. An overview can be found at www.ov-fiets.nl.
The website www.connexxion.nl tells you what regional bus line connects the place where you’re staying with the Defence Line of Amsterdam.
The forts can be reached easily by car. Do keep in mind, though, that the roads that lead to the fortresses can be narrow. Also there are often no parking facilities, so that you’ll have to park your car on the roadside.
General tourist information about the area and other attractions and activities that can be combined with a visit to the Defence Line can be found at:
Travel and accommodation: www.vvvkopvannoordholland.nl, www.vvvnoordzeekust.nl or www.iamsterdam.nl.