Ac­ci­dent night­mare at Dou­glas and Glen­luce Drive in­ter­sec­tion

The Star Early Edition - - POLITICS -


There has still not been any ac­tion on my nu­mer­ous e-mails over the past 18 months or so… I am at­tach­ing pic­tures of our lat­est ac­ci­dent, which is the third one in the past five days. It is re­ally get­ting out of hand now.

We des­per­ately need calm­ing traf­fic cir­cles at both the Dou­glas Drive and Glen­luce Drive in­ter­sec­tions, as well as Dou­glas Drive and King­fisher Road. Please let this be taken se­ri­ously be­fore more lives are lost here.

A study will be un­der­taken to de­ter­mine the fea­si­bil­ity of the pro­posal at the spe­cific in­ter­sec­tions. How­ever, as back­ground in­for­ma­tion, the JRA Traf­fic Engi­neer­ing unit re­sponds as fol­lows:

Each type of con­trol mea­sure is jus­ti­fied and based on in­ter­na­tional as well as lo­cal stan­dards con­tained in the SADC Road Traf­fic Signs Man­ual. The dis­ad­van­tages and ad­van­tages as­so­ci­ated with each mea­sure have been doc­u­mented ex­ten­sively in re­search pa­pers, all which are taken into ac­count when a de­ci­sion is taken on the most ap­pro­pri­ate


con­trol mea­sure from a traf­fic and road safety per­spec­tive.

Round­abouts equalise the pri­or­ity of all ap­proach roads. No mat­ter how mi­nor the in­ter­sect­ing road may be, it is af­forded the same pri­or­ity on en­try as any of the ma­jor routes. Fur­ther­more, all ve­hi­cles must slow and take gaps on ap­proach­ing the round­about and pri­or­ity can­not be given to any move­ment with­out vi­o­lat­ing the round­about op­er­a­tional prin­ci­ples. Mini-cir­cles, in par­tic­u­lar, must be avoided where the ma­jor road traf­fic is such that it will “force” pri­or­ity. If heavy main road traf­fic makes the mi­nor road or right­turn­ing traf­fic stop and give way, even though the cir­cle the­o­ret­i­cally gives the mi­nor traf­fic pri­or­ity, a dan­ger­ous sit­u­a­tion arises.

Un­suit­able lo­ca­tions for round­abouts are: 1. Where mi­nor cross­roads en­ter ma­jor routes. 2. In sig­nalised co-or­di­nated net­works where they would break up the pla­toon flow. 3. Where traf­fic sig­nals will soon be re­quired. As per the South African Road Traf­fic Signs Man­ual, 4-way stops must be used as an in­terim so­lu­tion where traf­fic sig­nals are war­ranted but fund­ing is not yet avail­able for the in­stal­la­tion thereof. 4. As is the case of all in­ter­sec­tions, round­abouts should be avoided on roads with steep slopes or where the in­ter­sec­tion is not vis­i­ble. Longer ‘flat’ ar­eas are re­quired for round­abouts com­pared with other in­ter­sec­tion types.

Var­i­ous data is col­lected prior to the in­stal­la­tion of any in­ter­sec­tion con­trol mea­sures. These in­clude:

Traf­fic Vol­umes Hourly in­ter­sec­tion ap­proach Turn­ing move­ment counts for the AM and PM peak pe­ri­ods

Fu­ture mod­elled in­ter­sec­tion ap­proach vol­umes

Fu­ture turn­ing move­ment vol­umes for the AM and PM peak hours us­ing pre- ap­proved growth rates or fu­ture mod­el­ling pa­ram­e­ters

Pedes­trian and bi­cy­cle vol­umes by ap­proach, if ap­pli­ca­ble

Crash Data Crash data from the JMPD ac­ci­dent database

Ex­ist­ing Geo­met­rics The ex­ist­ing geo­met­rics of the in­ter­sec­tion be­ing con­sid­ered in­clud­ing gra­di­ents, avail­able road re­serve, ser­vices, sight dis­tance, lane widths, park­ing lanes, shoul­ders and/or curb treat­ments, me­di­ans, pedes­trian and bi­cy­cle fa­cil­i­ties, right-of-way lim­its and ac­cess drive­ways or ad­ja­cent road­ways for all approaches.

Ca­pac­ity and War­rant Anal­y­sis Anal­y­sis de­ter­min­ing the de­lays for all move­ments, approaches and over­all in­ter­sec­tion for AM and PM peak hours, both ex­ist­ing and fu­ture con­di­tions, for each al­ter­na­tive an­a­lysed.

In or­der for the en­gi­neer to de­ter­mine if any traf­fic con­trol is nec­es­sary at an in­ter­sec­tion, data must be ex­am­ined to de­ter­mine if a “war­rant” is met for the par­tic­u­lar in­ter­sec­tion con­trol al­ter­na­tive. Even if a “war­rant” is met, it may not be the cor­rect ac­tion to take for a given sit­u­a­tion. The en­gi­neer must de­ter­mine if the treat­ment is “jus­ti­fied”.

These fac­tors could in­clude, but are not lim­ited to ex­ist­ing safety and con­ges­tion is­sues, fu­ture road mas­ter plans for the road­way, the spac­ing of nearby in­ter­sec­tions or drive­ways, fu­ture an­tic­i­pated traf­fic vol­umes, the dis­tance to the near­est traf­fic con­trolled in­ter­sec­tions, the amount of turn­ing traf­fic, the break­down and per­cent­age of types of ve­hi­cles, the amounts of non-mo­torised traf­fic, sight dis­tance, avail­able right of way, avail­able funds for con­struc­tion, sup­port of the lo­cal users. ca­ble theft, which re­sult in power out­ages.

In March this year, the city al­lo­cated an ad­di­tional R6 mil­lion to the JRA through the mid-year ad­just­ment process to en­able the ac­cel­er­ated im­ple­men­ta­tion of the No Joints Pol­icy.

This al­lo­ca­tion was also used to im­prove the JRA’s traf­fic light fault de­tec­tion sys­tems to im­prove sig­nal tim­ings and re­duce con­ges­tion, and for se­cu­rity surveil­lance of crit­i­cal in­ter­sec­tions prone to theft of in­fra­struc­ture such as ca­bles.

Ad­di­tional fund­ing was also pro­vided for hir­ing per­son­nel, and the JRA started a process of re­cruit­ing ad­di­tional traf­fic-light re­pair tech­ni­cians.

In the new fi­nan­cial year, R45m has been al­lo­cated for the re­place­ment of dam­aged ca­bles and R30m for in­stal­la­tion of un­in­ter­rupted power sup­ply (UPS) units at key traf­fic in­ter­sec­tions.

With the ad­di­tional fund­ing for UPS units, the JRA will be able to in­stall UPS units at 230 high-traf­fic vol­ume in­ter­sec­tions per an­num.

“I am en­cour­aged by the JRA’s progress in tack­ling faulty traf­fic sig­nals across the city. We are grad­u­ally turn­ing the tide on traf­fic con­ges­tion within the city.

“As the new ad­min­is­tra­tion, we will con­tinue to do all we can to tackle the city’s in­fra­struc­ture chal­lenges so we can cre­ate an en­abling en­vi­ron­ment for strong eco­nomic growth and op­por­tu­ni­ties for all,” Mukhuba added.

Just one of the many ac­ci­dents which hap­pen at an in­ter­sec­tion in Dou­glas Drive, Dou­glas­dale.

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