This paper was presented at the session titled `Risk management in the roads sector - geometric design'. Geometric design guidelines for chain-on/chain-off facilities are not found in design guides such as the Alberta Infrastructure 'Highway Geometric Design Guide', the Transportation Association of Canada (TAC) 'Geometric Design Guide for Canadian Roads' or the AASHTO 'a policy on Geometric Design of Highways and Streets'. In addition, signing and marking of chain-on/chain-off facilities are not contained in the TAC 'Manual of Uniform Traffic Control Devices for Canada'. While a few highway agencies in the United States and Canada have developed their own specific guidelines, they are often modified and applied on a case by case basis. The purpose of this paper is to present geometric design guidelines for chain-on/chain-off facilities. Also, presented are guidelines for the signing and marking of chain-on/chain-off facilities. The main purpose for developing these guidelines is to enhance safety and manage the risk of highway operation on steep upgrades and downgrades. In developing these guidelines selected highway agencies in Canada and the United States were contacted in order to obtain geometric guidelines and signing of chain-on/chain-off facilities. In addition, regional supervisors for Alberta Infrastructure and maintenance contractors were surveyed for their opinions concerning the need for chains on steep grades. Three classes of chain-on/chain-off facilities are presented which include determination of need and signing of the facility. Geometric design guidelines include cross-section, taper length, and parking areas. Signing guidelines are also presented. While the need for chain-on/chain-off roadside facilities are limited to highways in mountainous terrain or highway crossing steep river valleys in rolling terrain, they are an important geometric design feature and part of an overall risk management strategy for highway agencies. (A)
Samenvatting