We've been good friends since our childhood.She's 1&half yr older than me.These days I hardly get the opportunity to meet her as we both are busy with our jobs,but that really didn't affect our friendship.
I really like her,but I could never express my feelings in the fear of losing her and her friendship.
I get to meet her only in social occasions.I've noticed that there she always wants to be with me and we talk a lot over various stuff.During conversations,she often casually touches me(like on my shoulder, hand or knees)and hits me playfully if I make a joke of her.Sometimes she also wishes if we could meet more often.
Are these signs that she also likes me?Does this age-gap matter?

Age gap, does not look like one to me.

I know that you are not sure whether she feels the same way or not. I do believe that some of the best couples actually became really best friends first.

Remember there is no guarantee in any life experiances. The only way she will know how you feel is by telling her, and giving her a chanch to respond and see how things might develop.

The fact she is comfortable with you, is in no way meaning she wants more from you, and I would stay within the bounds of friends.

What age gap? Surely you don't mean a year and a half, that would only apply if she were in grade 3 and you were in 4 or 5:)

You cannot read her mind nor can you interpret her actions anymore than you can predict the future. Unless the signs were sooo blatant, which in your case they really are not, sounds like friends being friends to me.

Don't let fear prevent you from action. If you like her, ask her out, that's all you need to know.

It's impossible to know what she's thinking. If you tell her, you risk messing up the friendship. If you don't tell her, you might always wonder. So, it's up to you what you want to do. Maybe the next time she says that you guys should get together more, invite her to a party or a dinner with a group of friends you have in common. Then once you have spent more time with her, you might get a better idea of how she feels. But if you do ask her, be prepared if she says no. It will most likely be awkward then!

Well I think she likes you as a friend and because you are younger to her she touches you unconsciously , its normal in friendship but if you really like her and serious about her then show courage and tell her about your feelings , and suppose if she won't like you , you should manage the situation in a way that you don't loose your friend , to interpret or know what she thinks about this topic I'm ean love , you can ask her idea of love , her mr.perfect etc , takecare :)

Straight up, could mess the friendship. Or it could be the best experience of a lifetime and the perfect match. Staying within the bounds of friendship, I do not agree with that advice. Why not take the chanch. It is your decision and your decision alone.