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Thursday, September 13, 2007

Traffic Calming at DirectGov

Here's the stuff Flintshire Highways want to avoid for Chester Rd Penyffordd.
I would wish my elected councillors would look here.

Click here

and here


Speeds within Villages

Reductions in mean speed, over both directions, ranged from 2mph to 12mph, with 85th percentile reductions of up to 14mph. The largest reductions occurred in Costessey, Craven Arms and Thorney, where physical measures were used, and in Hayton with its high 'before' speeds prior to the reduction in speed limit from 60mph to 40mph. Individually, physical measures yielded speed reductions of between 7mph and 12mph.

A comparison between Pant and Dorrington, where the schemes were similar, shows greater speed reductions in Pant. These were mainly due to the change in speed limit, and could also have been influenced by the use of the speed limit roundels, the closer spacing of the patches and the lower 'before' speeds in Dorrington. However, the mean and 85th percentile speeds remained higher in Pant than in Dorrington. In Craven Arms and Pant the use of the repeater roundels reduced speeds by about 4mph to 5mph; however, similar markings in West Wellow resulted in average reductions of only 3mph.

The series of refuges, linked by centre hatching, in Copster Green had only a small effect, with a reduction in mean and 85th percentile speeds of only 2mph to 3mph.

In cases where fixed speed cameras were used (Thorney and Great Glen) additional speed reductions were no more than 2mph.

The target of obtaining 85th percentile speeds which did not exceed the speed limit, was seldom met. In Thorney it was achieved near the chicane (not shown in table 2). In Craven Arms it was achieved where the speed cushions were employed, but not on the sections where repeater roundels were marked. Elsewhere, 85th percentile speeds were above the speed limit.

Night-time mean and 85th percentile speeds were typically higher than daytime speeds, by 2mph to 4mph. Night-time reductions in speed were similar to, or slightly greater than, day-time reductions.

Traffic Flows

The lack of alternative routes for the trunk road villages meant that there was no change in the overall traffic flow levels, or in the proportion of heavy vehicles, after scheme installation. In Costessey there were some changes, and these are reported more fully in TA Leaflet 14/99.

Noise

Measurements of both vehicle noise (noise of individual vehicles passing over measures) and traffic noise (the overall effect of the scheme on ambient noise levels) were taken. These measurements were made in Thorney, Craven Arms, Costessey and Hayton.

For vehicle noise, the measures resulted in a reduction for both light and heavy vehicles which ranged from about 1 dB(A) to more than 10 dB(A). Further details of vehicle noise measurements for Thorney, Craven Arms and Costessey are contained in their respective TA Leaflets. In Hayton, vehicle noise surveys showed that the average maximum noise levels at the mean site speed were reduced by 10.5 dB(A) for light vehicles and 7.1 dB(A) for heavy vehicles. The surfacing (that is the textured surfacing used for the red patches and the resurfacing that took place before the patches were laid) appeared to contribute to the reduction in noise levels. A resident had complained of a 'pulsing' sound as vehicles crossed the textured patches. This was measurable but the fluctuation in noise levels was less than 1 dB(A) and only occurred with some types of cars. The reason for the complaint appeared to be the change in character of the noise, rather than an increase in noise.

For traffic noise, in all cases (except at the Craven Arms site at night) a reduction in overall traffic noise was achieved. This was largely attributable to reductions in speed. Daytime noise levels at Hayton fell by 8.6 dB(A) while night-time levels were down by 13 dB(A). Background daytime noise levels in Hayton fell by 9.4 dB(A) but night-time background noise levels were only reduced by 2.3 dB(A). This is due to the much lower traffic flows at night and, therefore, the less influence that traffic has on background (or ambient) noise levels.

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