The Dutch Ministry of Transport, Directorate Zuid-Holland plans to deal with the traffic capacity problems on the beltway of Rotterdam between the “Terbregseplein” and the “Kleinpolderplein” by extending the road network. One of the options is the design of new road infrastructure. In this, two alternatives are available, a motorway that connects RW16 and RW13, and extra road capacity on RW20 combined with a new rural road. The Directorate Zuid-Holland commissioned the TNO Human Factors Research Institute to evaluate 9 different tunnel design variants, with two RW16/13 variants, two RW20 variants, three rural road variants that will be built in case RW20 is chosen, and two variants of RW13 near Overschie (plexiglass covering and tunnel), also in case RW20 is chosen. This evaluation pays attention to the effect of tunnel design on driving behaviour, on the way road users experience driving through these tunnels, and on traffic safety. The evaluation showed that the RW16/13 alternative is preferred over the RW20 alternative. This alternative requires simpler route choice behaviour. The RW20 alternative requires rather complex entry and exit manoeuvres and route choices both inside and outside the tunnel within short distances. Besides this, the tunnel on RW20 is relatively long (minimum 3500m) compared to RW16/13 (maximum 1900m), something that can be experienced as unpleasant by road users. Within the RW16/13 alternative, the AB-curve variant is preferred, since this variant partly contains an open tunnel. A speed limit 100 km/h is advised here. In case RW20 is chosen, the variant with the short tunnel is to be preferred, since the route choice is less complex here. If RW20 is chosen, an additional rural road has to be built, of which three variants are available. Here, the AB-variant (2×2 lanes) is preferred, with six short tunnels. It must be noted that the physical separation of the two driving directions as well as the wide image of the lateral profile all variants (including the 2×2 variant with a 2100m tunnel and the 2×1 variant with a 2100m tunnel) will probably lead to high speeds, with as a consequence curve radii that are too tight. If the RW20 alternative is chosen, it is being considered to increase the quality of life near RW13 by building a plexiglass covering over part of the current RW13 or by building part of the road underground. Since not too many details are available on the exact design of the roof, a clear evaluation is not possible. However, it must be noted that the minimum curve radius in the tunnel variant is rather small, and that road users may experience a covering to be a tunnel, especially if the roof does not allow too much daylight if it is dirty. Finally, a 3-dimensional visualisation may help the designer tremendously in evaluating the different designs more in detail. (Author/publisher)
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