Rationalisation of urban freight transport for the greater Christchurch area: A feasibility study of transport elements required for an inland port in western Christchurch

Abstract

To rationalise urban freight transport, one must firstly understand how the current freight transport task is managed before any change can take place. There are many international studies that lead the way on this subject which could show how change may be achieved in Christchurch.

Establishing an inland port is one method which is proving successful overseas for cities of the same population and demographics as Christchurch.

A number of studies need to be taken to establish the feasibility of the individual components that make up the planning phase of an inland port for Christchurch. One of the first studies that need to be done is the feasibility of how the transfer of containerised cargo gets from the seaport to the proposed inland port. Overseas studies show that inter-modal transfer is the most successful and that rail is a key component of the transfer process.

For the purposes of this study a theoretical inland port has been sited in the western side of Christchurch alongside the main trunk rail line and State Highway 1.

To obtain an effective transfer of containers to and from the inland port, an understanding of the capacities of the seaport, rail and inland port operations is necessary. There are number of areas to be considered when calculating the capacity limitations of the operation. They are:

• Berth exchange (port crane capacity). The berth exchange is carried out by three container gantry cranes that can each discharge a maximum of 16 containers per hour, 48 containers per hour or a maximum total of 1,152 containers in 24 hours. • Straddle exchange (wharf to rail siding). A straddle crane can move a container in a round trip taking 2.5 minutes. Two straddles could transfer 48 containers in one hour. • Rail exchange (port loading & offloading of rail wagons). One straddle or a single gantry crane could load 24 wagons in 48 minutes. • Rail line capacity (number of trains required). There is a single line from the port to Heathcote and then a double line from there to Rolleston. There would be sufficient line capacity to cater for the container transfer as well as for other line users, coal, work, and general freight trains. • Transfer Time (train journey turnaround time). Transfer time depends on whether operational activities are sequential or concurrently. In a sequential activity scenario, the optimal transfer time would be 2 hours 34 minutes. In a concurrent activity scenario the optimal time would be 1 hour 58 minutes by remote shunter or 1 hour 48 minutes by a manned engine. • Inland port exchange (inland port loading & offloading of rail wagons). An assumption has been made that the inland port has similar resources as the sea port and therefore figures would be the same as the rail exchange above.

There are two methods of activity, sequential and concurrent, that relate to the movement of containers from the seaport and vice versa. The sequential method is based on the number of straddles applied to the loading or offloading process to decrease time and therefore increase the number of trains over a 24 hour period. The concurrent method is based on the number of trains and wagons transporting containers and therefore the more trains and wagons available the greater the number of containers able to be carried.

The concurrent activity scenario proves that there is sufficient time for a single straddle or a gantry crane to load or offload a 24 wagon train in the time it takes for a train to shunt and travel between the two ports based on a full rake in, empty rake out of vice versa.

It is unlikely that the ship discharge will be regular because of scheduling, vessel size and the number of containers being discharged, and therefore the rail operations may be spread over a longer time to minimise the resources being used.

The port and inland port operator will need to take into consideration costs versus operational performance and ideally they may want a balance of both.

It is recommended that operating two remote shuttles with four rakes of 24 wagons at each site would be the optimal scenario. This would allow for two rakes of 24 loaded wagons in transit and two rakes at each port being offloaded or reloaded. It would also achieve a transfer of 1,152 containers, the daily berth exchange limit. This scenario could be varied to handle fewer containers simply by reducing the number of train movements.