The gray behe­moth rest­ed atop a bright red semi trail­er, four dif­fer­ent types of valves pro­trud­ing from the top, as Den­ver fire­fight­ers and city offi­cials stood near­by, look­ing proud­ly at the department’s most recent high-dol­lar purchase.

Think of it almost as a rail­road car, said Mike Pylar, cap­tain of the Den­ver Fire Department’s haz­ardous mate­ri­als team. The dif­fer­ence is, this one can be moved by semi and is used to mim­ic vir­tu­al­ly any set­up a rail car car­ry­ing poten­tial­ly dead­ly chem­i­cals might have.

Pylar and oth­ers reviewed the department’s $150,000 train­ing tool Fri­day at the city’s fire sta­tion at 9150 E. 50th Ave. — a pur­chase that’s the cul­mi­na­tion of a years-long con­ver­sa­tion about how to be pre­pared for an acci­dent — or worse — on Denver’s rails.

Trains move dead­ly chem­i­cals like chlo­rine and ammo­nia through Denver’s res­i­den­tial and pedes­tri­an-heavy neigh­bor­hoods dai­ly, Pylar said. While crews already train to han­dle and mit­i­gate acci­dents or poten­tial attacks on those rail cars, they haven’t been able to train on any­thing so real­is­tic. At least not local­ly, he said.

“We can take this any­where and every­where,” Pylar said.

At-large City Coun­cil­woman Deb­bie Orte­ga was among those who began rais­ing con­cerns years ago about the risks of rail cars pass­ing through Denver’s neighborhoods.

The biggest con­cern is human error, Pylar said, although cities must also be pre­pared for the pos­si­bil­i­ty of ter­ror­ist attacks. A chlo­rine spill, or an attack on a car car­ry­ing ammo­nia, would be dead­ly, he said.

Through a grant from the Urban Area Secu­ri­ty Ini­tia­tive, the city was able to buy the “rail car train­er,” which Orte­ga, Pylar and oth­ers received with open arms Friday.

The train­er is already in use for train­ing exer­cis­es, Pylar said. Oth­er fire dis­tricts can bor­row the rail car and train their crews, he said. This is impor­tant because any extreme haz­ardous mate­r­i­al spill in the area will almost cer­tain­ly require a region­al response rather than a local one.