Travel speed and injury risk (1)

Transcription

1 Travel speed and injury risk (1) The power model and a new exponential function (From: The new Traffic Safety Handbook, Elvik et al 2012) 1

2 Travel speed and injury risk (2) A decrease by 20% of the mean speed results in a 40% reduction of fatalities If everybody in Sweden always complies with the speed limits there would be lives saved every year in Sweden år Real speeds of below 30 kphwill most probably lead to almost zero severe injuries 2

3 Feeling of safety -A pedestrian is not very strong especially not at higher speeds6. Kinetic energy relation: Car in 50 km/h vs pedestrian in 5 km/h: 1900 to 1 Car in 20 km/h vs pedestrian in 5 km/h: 300 to 1 3

4 But low speeds help a lot... Proportion of drivers yielding for and bicyclists at different approach speeds 4

5 Other implications of low speeds (maximum kph) Noise is reduced up to 13dB(A) between 50 and 20 kph With less need for acceleration and less air resistance the demand for energy will be lower, however we need city cars Restrictions on car traffic often stimulate shopping turnover Less cars lead to more peds and bicyclists lower risks Mobility for pedestrians is highly improved a new type of freedom The need for road space is going down to half when speed is lowered from 60 kph to 20 kph 5

6 The main drawback travel times will increase But primarily for motorised traffic But how much longer? (Average speeds in cities are maximum km/h). Traffic signals can be removed reduced travel time An average city trip of 5 km per car will take 3-5 minutes more Pedestrians and bicyclists will (always) gain time Drivers will forget the time aspect and instead enjoy the nice rythm (still primarily theory) 6

7 Conclusions Low speeds Low speeds with a minimum of accelerations and decelerations the way towards a sustainable and attractive city!? The problems of drawing more firm conclusions are simply because we have no test bed. There is no city that so far has produced a comprehensive planning and implementation - of traffic in towns, with priority for environmentally friendly modes of transport. 7

8 So6. Cities are still suffering Too much traffic and too high speeds. Politicians promote friendly modes of transport, however6 6.. they are like everybody else, e.g. they saysafety but they never do safety The only exception; parents to small children We need to understand the history6. 6. And we need to look at the system in a new way 8

9 The history of motorisation Car explosion no draw-backs, only benefits and optimism We are seduced by our fancy cars and an infrastructure that take up the competition We have produced a high-speed society 9

10 The infrastructure

11 0-100 kph in a whisper The car

12 The late latest from BMW6. They have changed the Speed Limiter: From 250 km/h To 305 km/h!! As a compensation they offer a one day have course6. (skill courses have never produced positive safety effects!)

13 In fractions of a second we have become car drivers Australopithecus Robustus Australopithecus afarensis miljyears Homo neanderthalensis Homo erectus Homo Homo sapiens autobilissimus , ? -2 million years... -0, mill years

14 Driving to-day6 We are sitting in our armchairs, listening to nice music, talking on the phone, at the same time as we are protected by ABS, ACC, AICC, ASR, BSD, CAS, DM, DSC, DSR, ESC, EDS, ESF, ESP, HBA, LDW, TSC, TPMS, NVS, NARVCW New Automatic Rear View Camera Washer), emergency braking, safety belt, air bags, alcolock, belt reminder, ISA, whiplash protection, stereo, mobile, dvd, Navigation System, etcetera What about the sustainable and safe city?

15 Implications Speed policy has been the most obvious laissez-fair strategy. The scientific backing of 50 and not 60 or 40 or 30 or 20 km/h - did not exist when speed limits were introduced There is no scientific back ground for the present conclusions regarding appropriate speeds in our cities especially seen in a sustainability context The norm to-day says that it is ok to override the speed limits with at least 5-10%. Autosafe in Sweden pays your speeding tickets6 Very unpleasant to comply with speed rules Cities need to do something now otherwise they will be extinguished 15

16 Universality My results are not directlyuniversally applicable, still my recommendation is: Do something with the speed problem before it is too late 16

17 Traffic calming is the first step Low and harmonised speeds can be reached resulting in significantly improved conditions Humps and small round-abouts are the key measures Negative mitigation seems likely; may be important positive implications. (May change the scope of driving a car) Any target speed can be reached locally, however6 6. speeds without accelerations and decelerations can not be reached without complementary vehicle measures 17

18 Vehicle measures Speed Limiter -a system that makes it impossible to override the prevailing speed limit ISA-Intelligent Speed Adaptation -a similar system but where overriding is possible if perceived necessary by the driver 18

19 Speed Limiter (SL) is replaced by ISA in urban areas! Speed Limiter is not accepted neither by Governments nor industry We have invested too much in our high performance cars But we have reached the peak in numbers in many countries 19

20 6even though SL is much more effective than ISA 6.the Market Driven one is substantially outperformed by the Authority Driven one. From: Lai et al. Accident Analysis & Prevention Volume 48, September 2012, Pages 63 72) Without SL With SL

21 General Conclusions We are slowly moving Great potential In the short run: combination of infrastructural and vehicle measures More empirii We must demonstrate and describe and explain I think all the conclusions are as valid everywhere around the globe. Traffic problems develop in the same way everywhere The (time)scale is different in different countries etc The earlier these ideas are introduced in Third World Countries the easier it will be 21

22 Pedestrians must raise their voice universally and univocally 22

23 Thank you 6. and best wishes 23