Based upon all the evidence I have seen, Metro appears to have a greater share in the fault. To the best of my knowledge though the investigations of that wreck have not been finalized yet, or if they have it hasn't been publicized.
It should also be noted that you CANNOT trust the Houston Chronicle to provide an accurate, complete, or even remotely objective story about anything that Metro is involved in. Why? Because they have a policy of intentionally slanting their news coverage to promote light rail - a fact that was inadvertantly revealed to the public last year when they accidently posted the memo detailing it onto the web. The story the wrote about the January 23rd wreck is no different.
As photos from the wreck site reveal, the truck that was hit was actually one of two UP crews working on the same section of track (Note: this was not reported by the Chronicle).
Those photos also reveal that the other truck was parked on top of the tracks in front of the crossing guard, which is part of the pre-existing freight railroad system and not metrorail's test track, which simply shares them and runs parallel to them. This also makes it equally if not more likely that the crossing bars were down due to the presence of the first repair crew and not metrorail. This is key because if the UP truck driver thought or knew that the other truck was in control of the crossing gates his own bypassing of those gates would have been perfectly legitimate (Note: this was not reported by the Chronicle)
As the photos from the scene also reveal, a civilian vehicle was waiting outside of the gates at the crossing that was blocked by the other UP vehice. It was waiting there because of that other UP vehicle, NOT metrorail (Note: this was not reported by the Chronicle)
And as reports of the accidents reveal, metrorail was travelling at a speed substantially in excess of the absolute fastest rate it will ever travel in normal operations, giving more than enough reason to question the need to operate it in such a manner (Note: this was not substantially considered by the Chronicle).
As I noted previously, an analogy demonstrates the clear bias of the Chronicle and others who assign blame upon UP. Suppose that the UP crew was a road repair crew working on an interstate. Suppose metrorail was a motor vehicle, and suppose that vehicle also recieved full notice that a road crew was working on the interstate where they travelled a few miles ahead. Now suppose a worker in that road crew, which consisted of several teams and was visible from at least a half mile back, briefly stepped around one of the orange cones to access the other side of the road he was working on. As he did so, other vehicles in the area (such as a car at a nearby intersection) waited for the crew to finish its work before proceeding on their own. Yet the motorist on the interstate, fully aware of that crew yet still travelling 20 mph above the normal speed limit to say nothing of standard construction zone reductions, decided he would plow through there anyway without making any adjustment or compensation for the fact that the road was being worked on. He hits the repair crewman in the crossing after making a late but ineffective attempt to brake and severely injures him in the process. QUESTION: Under the standard law of practically every single state in the union, who is at primary fault?
The answer will virtually always be the motorist, and so should it be with metrorail.