Add and edit intersection sight lines to roundabouts that were created with vehicle envelopes based design guidelines. An approach to crosswalk sight line determines the areas along the side of the road where objects should not be placed so the driver can see the pedestrians at the crosswalk. The approach to crosswalk distance is measured from the vehicle front to the edge of the crosswalk, with an accuracy of equal to or better than 6 inches.

Note:

• Intersection sight line is equivalent to Criterion 2 and 3 sight line in Australian guidelines.
• The starting point for the vehicle paths is represented by a line which goes from the driver’s eye to the crossing of the vehicle path and the inscribed circle. The vehicle stop point is located along the entry path, i.e. specified straight distance from the crossing of the path and the inscribed circle.

Edit Sight Line - Intersection Dialog Box

Distance to Yield Line

Specify the distance to yield line value. This is the setback distance from the conceptual yield line (inscribed circle) to the design vehicle when evaluating intersection sight distance.

Critical Gap

Specify the critical gap value. This is the duration of time needed for an entering vehicle to safely enter the roundabout without interfering with upstream or circulating stream vehicles. By default, the Critical Gap value is set to 6.5 s.

Initial Entering Speed

Specify the initial entering speed value. This is the initial speed of the upstream vehicle when evaluating intersection sight distance. By default, the Initial Entering Speed value is set to the R1 velocity of the upstream approach (see Evaluate Fastest Path).

Minimum Entering Sight Distance

Displays the minimum entering sight distance. This is the sight distance calculated based on the entering stream sight distance equation using the Initial Entering Speed value above. TORUS uses the Minimum Entering Sight Distance value to determine the intersection sight line and the obstruction free zone.

Initial Circulating Speed

Specify the initial circulating speed value. This is the initial speed of the design vehicle circulating the roundabout. By default, the Initial Entering Speed value is set to the R4 speed (see Evaluate Fastest Path -> TORUS Generated Roundabout and Evaluate Fastest Path -> User-Drawn Roundabout). .

Minimum Circulating Sight Distance

Displays the minimum circulating sight distance value. This is the sight distance calculated based on the circulating stream sight distance equation using the Initial Circulating Speed value. uses the Minimum Circulating Sight Distance value to determine the intersection sight line and the obstruction free zone.

Driver's Eye Location Section

Distance from Front

Specify the distance from front value. This is the distance from the front of the design vehicle to the driver's eye

Distance from Driver's Side

Specify the distance from the driver's side value. This is the distance from the driver's side of the design vehicle to the driver's eye.

TORUS calculates the intersection sight line based on the following AASHTO equations:

dEntering Stream = 0.278 (VEntering Stream) (tc)	(metric)
where:	dEntering Stream = sight triangle length, m VEntering Stream = associated speed, km/h tc = critical gap, by default assumed to be 6.5 s

dEntering Stream = 1.468 (VEntering Stream) (tc)	(U.S. customary)
where:	dEntering Stream = sight triangle length, ft VEntering Stream = associated speed, mph tc = critical gap, by default assumed to be 6.5 s

dCirculating Stream = 0.278 (VCirculating Stream ) (tc)	(metric)
where:	dCirculating Stream = sight triangle length, m VCirculating Stream = associated speed, km/h tc = critical gap, by default assumed to be 6.5 s

dCirculating Stream = 1.468 (VCirculating Stream) (tc)	(U.S. customary)
where:	dCirculating Stream = sight triangle length, ft VCirculating Stream = associated speed, mph tc = critical gap, by default assumed to be 6.5 s