What is the fine-grained topic of the following text: CH2M Hill has recenntly successfully delivered the construction for the 2012 London Olympics as the Olympic Delivery Authority’s delivery partner in joint venture with Laing O’Rourke and Mace, and is working as programme manager on Crossrail. Only return the topic.
CH2M Hill's participation in construction projects including the 2012 London Olympics and Crossrail program.