Siemens EH.75M.11. Especificaciones descargar pdf (Pagina 47)

T400 Controller Facilities Manual

667/EB/20200/000 Page 6-1 Issue 9

6. HIGH SPEED VEHICLE DETECTION

To provide this facility, an SDE/SA processor PCB and soundmark interface socket

must be added to the controller. This fits in the PCB module beside the Main

Processor Board. Unused input lines on the SDE/SA PCB may be used as general

inputs.

On roads where high speed vehicles are required to be detected to ensure safe passage

through an intersection, one of two methods may be used:

- SDE, double or triple, where a fixed extension is generated.

- SA, where a fixed extension is generated after a variable delay dependent on

the vehicle speed.

6.1 SPEED DISCRIMINATION EQUIPMENT (SDE)

Each traffic lane is provided with either one or two speed measurement points,

assessors, situated further from the stop line than the normal detectors, to implement

either double or triple SDE. An assessor consists of two loops (A and B) with a 12ft

leading-edge to leading-edge spacing. The loop-loop traversal time gives a measure of

the vehicle speed. A vehicle travelling over an assessor above a preset threshold

generates a preset extension for the approach phase green, to retain ROW until the

vehicle reaches the normal point of detection.

See Figure 6.1(a) and (b) for a sketch of the layout.

6.1.1

Double SDE

This facility is used at intersections where vehicle approach speeds in excess of 35mph

(56Km/hr) and less than 45mph (72Km/hr) are normally anticipated. Alternative speeds

may be configured if required.

The standard assessment speed is 30mph (48Km/hr) and the distance of the assessor is

79 metres from the stop line. A fixed extension period normally of 3.0 seconds is

provided for each vehicle exceeding the threshold velocity. Alternative extension

periods may be configured if required.

6.1.2

Triple SDE

This facility is used where vehicle approach speeds in excess of 45mph (72Km/hr) and

less than 65mph (105Km/hr) are normally anticipated. Alternative speeds may be

configured if required.

Two assessors are used, an outer and an inner. The outer is situated 159 metres from

the stop line and the inner 91 metres. The outer assessor has a threshold velocity of

45mph (72Km/hr) and the inner 35mph (56Km/hr). A fixed extension period normally

of 3.5 seconds is provided by each assessor for vehicles exceeding the threshold

velocity. Alternative extension periods may be configured if required.

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Siemens EH.75M.11. Especificaciones Pagina 47