WHEREAS the purpose of Alberta’s provincial highway system is to provide for the safe and efficient movement of people and goods; and
WHEREAS the diversity of vehicles and equipment on Alberta’s provincial highways ranges from vehicles operated by the general public to commercial, industrial and agricultural equipment; and
WHEREAS the Government of Alberta has identified High Tension Cable Barriers (HTCB) as the preferred barrier system and is a standard to replace the traditional guardrail systems where feasible; and
WHEREAS the Government of Alberta has conducted performance evaluations on the safety and operational performance of HTCB for use in medians between multi-lane roadways only; and
WHEREAS there is the potential for safety concerns created by having HTCBs installed on the shoulders (particularly both shoulders) of rural two-lane highways;
THEREFORE, BE IT RESOLVED that the Alberta Association of Municipal Districts and Counties urge the Government of Alberta to review Alberta Transportation’s Standard Practices for installation of High Tension Cable Barriers (HTCBs) on two-lane provincial highways to ensure Alberta has the safest possible highways.
Since 2012, the province has identified HTCBs as the preferred barrier system and a standard to replace the traditional guardrail system. The province has advised that between 2014 and 2016 approximately 23 km of HTCB have been installed in the North Central Region. These devices consist of metal posts fixed into the sides of the roadways, often being located very close to the driving lanes, with metal cables extending the length of the barrier. HTCB height is generally 42 inches compared to the traditional guardrail at 28.75 inches or 32 inches high for new guardrails.
Evaluation of the safety and operational performance of HTCB installed in the median of multi-lane roadways has been conducted by several jurisdictions including Europe, New Zealand, United States and Canada. In Alberta, the Deerfoot Trail project in Calgary in 2011 and the Highway 2 project in 2013 have provided relatively conclusive evidence that HTCBs significantly reduce cross-median collisions, nearly eliminate cross-median fatalities, and reduce the number of severe injury cross-median collisions with a general increase in property damage only collisions. EBA Engineering Consultants Ltd. performed both evaluations and suggested that as a result of HTCBs the vast majority of head-on, sideswipe-opposite direction and off-road left collisions will be converted to median type crashes and that the median type crash severity is reduced due to the energy absorption characteristics of the flexible barrier system.
When HTCBs are installed in the median between multi-lane roadways the value of these devices is clear, so what is the problem?
When HTCBs are used on rural two-lane highways, the hazards created by HTCB are potentially much greater than the dangers they are meant to alleviate.
Currently the County of Barrhead has two locations where HTCBs were installed by Alberta Transportation in conjunction with a road project. Both locations require review based on the concerns above. In addition, standards for installation of HTCB including placement and/or height, or potential alternatives must be reviewed on a site by site basis to ensure the safest possible highways in Alberta.
Attachment – Example of HTCBs on a two-lane highway in the County of Barrhead.
The AAMDC has no active resolutions directly related to this issue.
Where there are hazards, a mitigation strategy is required to reduce the severity of incidents where vehicles run off the road. If the hazard cannot be removed, relocated, or modified, the next best option is to protect drivers from it. High Tension Cable Barriers (HTCBs) are proven to prevent or reduce the severity of crashes where vehicles run off the road. They are the most forgiving barrier system available for reducing the severity of off-road crashes, provided a suitable operating space is available.
An October 2016 design guide available on the Alberta open government portal includes guidelines for an HTCB installation in the median and on the roadside. This bulletin includes guidelines such as the placement, and the height on undivided highways, considering wide loads, farm equipment, and nuisance hits.
As outlined in the bulletin, it is best to set HTCBs as far back from a road as practical in the interest of accommodating wide loads, farm equipment, and reducing the frequency of nuisance hits. This approach provides more lateral space and reduced barrier height compared to an installation at the edge of a road.
A suitable flat slope on the side of the road allows for an offset between the edge of a shoulder and the barrier system. If a flat slope is not available, an HTCB must be placed at the pavement’s edge (the edge of the shoulder on unpaved roads).
Both the barrier height, and the lateral offset of an HTCB, affect the ability to accommodate wide loads and farm equipment. Designers have the following options:
On two-lane highways, motorists’ ability to escape a cross-over (head-on) collision is not affected by the presence of an HTCB or a conventional barrier. In addition, HTCBs:
The Government of Alberta’s response includes information detailing design options to ensure that HTCBs on two-lane highways are as safe as possible and do not impact snow removal or oversized vehicle travel on such highways. However, the resolution requests Alberta Transportation to review the current practices, which the response does not indicate a willingness to undertake.
This resolution is assigned a status of Intent Not Met and the AAMDC will continue to advocate on this issue.