Section 2 : Timetabling Continued

Elimination of excess layover to save a bus

An examination of the operation of these two services shows that a total of seven buses are used. Furthermore, it can be seen that in both cases there is excess layover

• 4 minutes on service number 2
• 6 minutes on service number 5

It’s the total amount of excess layover which will be the deciding factor as to whether or not a bus can be saved by interworking i.e. joining together two or more separate services operationally.  To enable this to happen, the following factors must apply:

• if the total excess layover on two or more independently operated services is equal to or greater than the service headways, a bus can be saved by interworking
• headways must be compatible
• there must be at least one common terminal point
• vehicles must be of a common type

On the two services in question, all the above points are satisfied

• total excess layover (4 + 6) = 10, which is exactly the same as the headway
• headways are compatible by being the same
• the service share a common terminal – Town Centre

Calculate the number of buses required by interworking

The scheduling formula should now be amended to consider the Round Journey Time of Service 2 and the Round Journey Time of Service 5, as the Total Round Journey Time.

The formula now looks like this:

36 + 24 / 10 = 60 / 10 = 6 buses

Joint Working Timetable

Bus No	4	5	6	1	2	3	4	5	6	1	2	3	4	5	6	1	2
Service No				2	2	2	2	2	2	2	2	2	2	2	2	2	2
Town Centre				0700	0710	0720	0730	0740	0750	0800	0810	0820	0830	0840	0850	0900	0910
Goodwin				0716	0726	0736	0746	0756	0806	0816	0826	0836	0846	0856	0906	0916	0926
Goodwin				0718	0728	0738	0748	0758	0808	0818	0828	0838	0848	0858	0908	0918	0928
Town Centre				0734	0744	0754	0804	0814	0824	0834	0844	0854	0904	0914	0924	0934	0944
Service No	5	5	5	5	5	5	5	5	5	5	5	5	5	5	5	5	5
Town Centre	0706	0716	0726	0736	0746	0756	0806	0816	0826	0836	0846	0856	0906	0916	0926	0936	0946
Corncross	0716	0726	0736	0746	0756	0806	0816	0826	0836	0846	0856	0906	0916	0926	0936	0946	0956
Corncross	0718	0728	0738	0748	0758	0808	0818	0828	0838	0848	0858	0908	0918	0928	0938	0948	0958
Town Centre	0728	0738	0748	0758	0808	0818	0828	0838	0848	0858	0908	0918	0928	0938	0948	0958	1008

The nature of the interworking has influenced the departure times on service No. 5, with buses leaving the Town Centre at 06 and every 10 minutes past the hour whereas previously they left at 00 and every 10 minutes past the hour.