A dump truck driver last year may have never seen an oncoming Amtrak train before it was too late, federal investigators concluded in a report, finding that a steep, poorly designed railroad crossing in rural Missouri contributed to last year’s fatal Amtrak derailment that killed four people and injured 146 others.

The National Transportation Safety Board said Wednesday that the 45-degree angle where the road crossed the tracks made it hard for the dump truck driver to see the approaching train, and the steep approach discouraged the truck driver from stopping beforehand.

“The safest rail grade crossing is no rail grade crossing. But at the very least, every road-rail intersection should have an adequate design to ensure proper visibility so drivers can see oncoming trains,” NTSB Chair Jennifer Homendy said. “Communities across the country deserve safer crossings so these types of accidents don’t happen again.”

The NTSB said the dump truck driver didn’t stop before continuing through the crossing at a speed of about 5 mph. The train was travelling 87 mph (140 kph) — close to the 90 mph speed limit for the area in western Missouri — at the time of the collision.

The NTSB has previously said investigators didn’t find any problems with the train’s brakes or other mechanical issues.

The crossing near Mendon where the collision happened didn’t have any lights or signals to warn that a train was approaching. Before the crash, area residents had expressed concerns for nearly three years about the safety of the crossing because of the lack of visibility. Another dump truck driver who witnessed the crash told investigators that he didn’t typically stop at the crossing either because the steep grade of the gravel road entering the crossing made it hard to start up again.

The state Transportation Department had put the $400,000 project to add lights and gates at the crossing on a priority list, but it hadn’t received funding before the derailment.

The Mendon crossing was closed immediately after last year’s crash. State officials will announce a $50 million plan to upgrade rail crossings statewide along tracks that passenger railroads use Thursday. Those projects will focus on the 47 passive crossings on three tracks that carry passenger trains although the NTSB said last year that Missouri has about 3,500 crossings like that statewide.

Roughly half of all rail crossings nationwide — some 130,000 of them — are considered passive without any lights or arms that automatically come down when a train is approaching.

For years, the NTSB has recommended closing passive crossings or adding gates, bells and other safety measures whenever possible. The U.S. Transportation Department recently announced $570 million in grants to help eliminate railroad crossings in 32 states but that funding will only eliminate a few dozen crossings.

Federal statistics show that roughly 2,000 collisions occur every year at rail crossings nationwide, and last year nearly 250 deaths were recorded in car-train crashes.

The people killed in the Amtrak derailment included the dump truck driver, 54-year-old Billy Barton II, of Brookfield, Missouri, and three passengers: Rochelle Cook, 58, and Kim Holsapple, 56, both of DeSoto, Kansas, and 82-year-old Binh Phan, of Kansas City, Missouri.

The Missouri State Highway Patrol said up to 150 people also were injured.

The Southwest Chief was traveling from Los Angeles to Chicago when it hit the rear right side of the truck near Mendon. Two locomotives and eight cars derailed. The train had 12 crewmembers and 271 aboard.

Several lawsuits were filed against BNSF after the derailment because that Fort Worth, Texas-based freight railroad owns and maintains the tracks involved.

Amtrak and BNSF estimated that the derailment caused roughly $4 million damage to their equipment and tracks.