Question $2$ Traffic Signals

A traffic volume study was conducted at a Cross Roads Junction on the outskirts of Cork City. The results of the survey are given in Table $2\mathrm{.}1,$ showing the number of vehicles approaching the Cross Roads. The North$/$South approach is $14\mathrm{.}6$ m wide; the East$/$West approach is $7\mathrm{.}3$ m wide.

Table $2\mathrm{.}1$ Approaches to the junction

$2\mathrm{.}1.$ Sketch the junction; indicating vehicular traffic phases.

$(5$ marks$)$

$2\mathrm{.}2.$ Generate the interval timing diagram.

$(28$marks$)$

Assumptions$/$Notes:

$-$ A pedestrian phase should be allowed for on both carriagewavs. On the pedestrian phase, allow for a reaction time of $3$ seconds, a walking speed of $\backslash (1\mathrm{.}3\backslash$mathrm$\{$~m$\}/\backslash$mathrm$\{$s$\}\backslash )$ and a margin of error of $1$ second. Allow for someone starting to cross the road $($at a walking speed of $\backslash (1\mathrm{.}3\backslash$mathrm$\{$~m$\}/\backslash$mathrm$\{$s$\}\backslash ))$ just as the lights go amber, to get to the other side before the next vehicular traffic phase. Allow for $4$ seconds of red interval on the pedestrian phase before the vehicular phase recommences.

$-$ For small right turn flows $(\backslash (<mn>1</mn><mn>2</mn><mn>0</mn><mtext></mtext><mi>\backslash </mi><mi>)</mi>$ per hour$)$ provide no separate provision; if no separate provision, assume right turners $\backslash (=1\mathrm{.}75\backslash )$ straight or left turners.

$-$ Allow for $3$ seconds of amber and $2$ seconds of red on vehicular phase; assume a reaction time for vehicles of $2$ seconds.

$-$ Use a cycle time of $120$ seconds.