An evaluation of the Australian Black Spot Programme published by the Bureau of Transport and Communications Economics revealed that in the period after treatment, there were substantial reductions in crashes at the 254 sample sites studied, relative to the period before the treatment. Fatalities fell by one-third, hospitalisation injuries by two-thirds and injuries requiring medical treatment by almost one-half. In the Victorian sample of projects, serious injury crashes dropped by 50 percent and other injury crashes by 58 percent.
The treatments showed themselves to be cost effective with net benefits of $800 million to the Australian community, generating returns of around $4 for each dollar of expenditure.
The study also found that Black Spot treatments had a greater influence on right-angle and right-turn crashes. However this is desirable as these crashes are associated with more serious injury.
The study was based on Black Spot treatments in Australia commencing in 1990 and continuing into the early 1990's. These early Black Spot projects were partly aimed at testing the effectiveness of Black Spot treatments. Most of the projects were in Victoria, the remainder in New South Wales.
The researchers concluded that "The results of the evaluation strongly suggest that the Program has achieved its aim of improving locations with a history of crashes involving death and serious injury."
Also, although I am unaware of any research on the topic, it must be noted that the current Queensland government has spent an amazing $744million on the road system. The road toll is now as low as it was before they first introduced traffic radar. Although the decline in the road toll slowed in 1997 this doesn't mean that the road work isn't saving lives. Speed cameras were introduced in 1997. This may have scared some people into slowing down thus creating a dangerous speed differential which offset the decline due to the roadwork.
Analysis of data on traffic fatalities and accidents in the Traffic Safety Facts 1994 published by the National Highway Traffic Safety Administration (NHTSA) by the Road Information Program (TRIP) showed that seventy-seven percent of all fatal traffic accidents occur on two- lane roads. TRIP is a nonprofit transportation research group.
TRIP research also indicates that fatal accidents are more than twice as likely to take place on two-lane roads than on highways with four lanes or more.
William M. Wilkins, executive director of The Road Information Program (TRIP) stated that "Road improvements such as wider lanes and widening shoulders and paving existing shoulders, adding a median and upgrading roads from two lanes to four lanes can significantly reduce traffic accidents, fatalities and injuries. Other road safety factors include providing crash barriers, better signage and lighting."
Other findings from TRIP's analysis of the data include:
Upgraded roads that went from two lanes to four lanes with a median enjoyed a 71 percent reduction in fatal accidents.
Widening a lane can reduce fatalities by 21 percent.
In 1994, 77 percent of fatal accidents occurred on two-lane roads. Two lane roads carried just 51 percent of total vehicle miles traveled.
In 1994, roads with four lanes or more had 13.8 percent of fatal accidents in spite of the fact that they carried 41.7 percent of travel.
The fatal accident rate per hundred million miles traveled on two-lane roads was 2.03. The fatal accident rate on roads with four or more lanes averaged 0.95.
The total number of traffic accidents follows a similar pattern. Two-lane roads hosted more than 2.7 million traffic accidents in 1994, compared to about 1.4 million accidents on roads with four or more lanes.
"It simply stands to reason that if drivers have more room to operate and additional space to return a vehicle to the road, then traffic accidents can be reduced," Wilkins asserted. "This is especially true when you consider how going from a two-lane road to a four-lane road can help reduce head-on collisions, which often result in more serious or fatal accidents."