4intersections.ppt

Intersections The main factors Number of legs Angle of intersection Sight distance Alignment Auxiliary lanes Channelization Friction Turning radii Lighting Lane and shoulder width Driveways Right of way ( rules,sign,signals) Approach speed Type of intersection Uncontrolled intersections Offside priority rule (give way to the right if vehicles drive on the left, and give way to the left if vehicles drive on the right); Nearside priority rule (give way to the left if vehicles drive on the left, and give way to the right if vehicles drive on the right); Terminating road rule (applicable at T-intersections: Traffic on the stem of the ‘t’ (which has to slow down anyway) give way to through on the top of the ‘t’; or Vehicles have priority in the order in which they arrive GIVE WAY (YIELD) or STOP Signs Priority controlled intersections STOP versus GIVE WAY(YIELD) control There are intersections which comprise a major or priority road, usually running straight across the intersection, and one or more roads which intersect it, with traffic on the minor roads being controlled with STOP or GIVE WAY(YIELD)signs. Roundabouts_applicable At intersections where traffic volumes would lead to unacceptable delay to traffic on the minor road with STOP or GIVE WAY control High left turning volumes More than four approaches At intersections between collector street, or between a collector and local street, where a disproportionally high number of accidents occur. On local street as part of a traffic management strategy to control speeds At rural cross intersections, where there is an accident problem involving vehicles on adjacent approached or turning vehicles The main traffic flow turns through a right angle, e.g. where a main road passes through a rural town Major roads insect at ‘Y’ or ‘t’ intersection Roundabout_less suitable Satisfactory geometric design cannot be provided due to space or topography Traffic flows are unbalance with high volumes on one or more approaches which