1 Background

1.1 Subsequent to the submission of Environmental Impact Assessment (EIA) Report on the Improvement to Castle Peak Road between Ka Loon Tsuen and Siu Lam (hereafter the Project) for design year 2022, it is noted that the northern section of Route 10 would not be required until after 2010. Since Siu Lam Link Road (SLLR) is planned for connecting the northern section of Route 10, its completion would also be deferred to tie in with the programme for the northern section.

1.2 Since SLLR is planned for connecting to Tuen Mun Road in the vicinity of the study area, it is necessary to conduct a traffic forecast to verify whether the traffic volumes for the case of without SLLR in year 2010 on Castle Peak Road New Link would be higher than the projected figures for 2022.

1.3 This paper briefly outlines the general approach, assumption and comparison results for the purpose of the EIA review.

2 General Approach and Assumptions

2.1 A similar approach and modeling methodology as described in Final Traffic Impact Assessment (TIA) Report submitted to relevant government departments in April 2000, has been adopted for this exercise. The general approach and methodology including the projected traffic flows presented for 2022 has been agreed by the Transport Department.

· Based on the discussion with the Client, Highways Department, the following assumptions were agreed to use for the purpose of this traffic forecast exercise:

· Since there is no planning data established for year 2010, planning data including Origin and Destination (O/D) matrices for year 2011 would be used. This would represent a worst scenario for this exercise.

· As identified in the previous TIA that the critical peak for traffic flows is the PM peak hour. Therefore, traffic forecast for this exercise would focus on the PM peak hour only.

· 2011 road network would be used and SLLR would be deleted for from the network. 2011 O/D matrices would be revised by deleting the external zone, northern section of Route 10, while the other external zones would remain unchanged. The revised O/D matrices would then assign to the 2011 road network without SLLR.

3 Traffic Forecast Results

3.1 Based on the Consultant’s in-house traffic model developed for this Project, the projected traffic flows for 2011 without SLLR is presented in Figure 3.1 together with the projected figures for 2022 previously conducted for comparison purpose.

3.2 As can be seen for Figure 3.1 that the projected 2011 traffic flows on Castle Peak Road New Link would be lower than the projected 2022 figures. This is expected since the traffic assignment is a capacity constraint assignment. In other words, if SLLR is not connected to Tuen Mun Road in year 2011 due to the programme deferral, less traffic would be expected on Tuen Mun Road resulting more residual capacities. As a result, a portion of the traffic originally using Castle Peak Road New Link would divert to Tuen Mun Road via Sham Tseng and Siu Lam Interchanges.

4 Summary of Findings

4.1 A traffic forecast exercise verifying whether the traffic volumes for the case of without SLLR in year 2011 on Castle Peak Road New Link would be higher than the projected figures for 2022 was conducted for the EIA review purpose.

4.2 Traffic forecast results indicated that the projected 2011 traffic flows on Castle Peak Road New Link would be lower than the projected 2022 figures. Therefore, the forecasted traffic flows for 2022 would still be the highest figure within a 15 year period after the completion of the Project. Thus, the projected 2022 traffic flows would still be valid to use for purpose of the EIA study.