Train sets are a classic childhood toy and something your child will play with for years as you add new pieces and their designs get more complex. A good suggestion is to break the set apart at the end of the day. Every time your child plays he/she can build a new one thus decreasing their chance of getting bored with the same track and by allowing their brain to create a new design every time they get it out. This will enhance cognitive skills such as logical and creative thinking.
I would say most children over age 2 could play with a train set, however the trains and accessories could have small detachable parts that may not be safe if your child still mouths their toys. In light of the major Thomas and Friends recall for lead paint, I cannot recommend any Thomas sets until the matter is cleared up. Also, another note about train sets - electronic engines take away from the child's own play therefore decreasing the interest level. If a child is moving the train around the track himself he is more active and involved than passively watching while it goes around without his help. Electronic sets are best suited for older children who are more interested in creating elaborate tracks as a hobby.
My personal favorite brand of wooden railway sets is BRIO. They have been around for a long time and are created as an heirloom toy, meaning they will last for generations. This is BRIO's Jungle Safari Figure 8 Set, a good starter set that includes a bridge, animals, conductor, and car that carries animals. BRIO makes expansion packs with more track pieces as well as different bridges, engines, turntables, and roundhouses. BRIO trains are easy to add to which will keep your child interested for years.
Oompa Toys offer train sets from Heros like this Super 8 Set. They have a cute video, too, showing the owner's son playing with his set. Heros doesn't have as many individual accessories available as BRIO does, but if you buy one of the larger sets you may get some of the pieces you're looking for.
Maxim offers several accessory pieces that are compatible with both BRIO and Thomas. I love their bridges and tunnels like this Mountain Tunnel I found at Wooden Railway Adventures. My son is actually getting this one for Christmas to expand his BRIO set.
This Fairy Train Set from Chasing Fireflies is so girly, so if older brother doesn't want to share his beloved set, this one is just too cute to pass up. I'm not sure who makes is but it's adorable!
One more note: when shopping for train sets, google the set you are looking for and browse about 5 different sites. Prices vary from store to store and this is a good way to ensure you get the best price. This goes without saying for any toy you are buying online.
Websites that sell wooden railway sets:
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