Train Icons for Gamification on "The Yelp for IT"

This is what IT Central Station was looking for in their icon design

The Wall Street Journal calls us "The Yelp for IT". On our site, users write reviews of enterprise tech products from companies such as IBM, Cisco, EMC, etc.

We are coming out with a new badge/gamification feature - the more reviews you write, the higher badge icon level you get. There are six levels:
Choo Choo Train (lowest level)
Caboose
Trolley
Commuter Rail
Train
Bullet Train (highest level)

You should create these 6 icons.

The icons should be no larger than 25px wide x 18px tall.

The colors/style should match our site: http://www.itcentralstation.com/products/quality-center

The badge icon would appear next to the "Real User" / Consultant badge for each user.
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