A Mercer County man died in a crash Thursday on Crosswicks Hamilton Square Road after crossing traffic and a grassy field before hitting a tree, Hamilton police said Friday. At about 4 p.m. Thursday, Hamilton police responded to a crash on Crosswicks Hamilton Square Road that killed Shane T. McKenna, of Hamilton. McKenna was declared dead at the scene. No age was given for McKenna by police. A preliminary investigation indicated that McKenna was driving northbound on Crosswicks Hamilton Square Road when he collided with a guardrail, crossed over southbound traffic, left the road and crossed a …